NRF52_esb

Files at this revision

API Documentation at this revision

Comitter:
wkleunen
Date:
Thu Feb 04 10:36:44 2021 +0000
Parent:
0:a01a54c0dc90
Commit message:
Initial compile;

Changed in this revision

main.cpp Show annotated file Show diff for this revision Revisions of this file
mbed-os.lib Show annotated file Show diff for this revision Revisions of this file
mbed.bld Show diff for this revision Revisions of this file
micro_esb.c Show diff for this revision Revisions of this file
micro_esb.cpp Show annotated file Show diff for this revision Revisions of this file
micro_esb.h Show annotated file Show diff for this revision Revisions of this file
nrf_esb.c Show annotated file Show diff for this revision Revisions of this file
nrf_esb.h Show annotated file Show diff for this revision Revisions of this file
nrf_esb_error_codes.h Show annotated file Show diff for this revision Revisions of this file
nrf_esb_resources.h Show annotated file Show diff for this revision Revisions of this file
diff -r a01a54c0dc90 -r 66f95e364222 main.cpp
--- a/main.cpp	Mon Mar 23 04:09:41 2015 +0000
+++ b/main.cpp	Thu Feb 04 10:36:44 2021 +0000
@@ -11,6 +11,8 @@
 #include "nrf_delay.h"
 //#include "nrf_gpio.h"
 
+
+
 static uesb_payload_t tx_payload, rx_payload;
 
 void uesb_event_handler()
@@ -26,7 +28,7 @@
     
     if(rf_interrupts & UESB_INT_TX_FAILED_MSK)
     {
-        uesb_flush_tx();
+       uesb_flush_tx();
     }
     
     if(rf_interrupts & UESB_INT_RX_DR_MSK)
@@ -36,7 +38,7 @@
         NRF_GPIO->OUTSET = (uint32_t)((rx_payload.data[2] & 0x0F) << 8);
     }
     
-    uesb_get_tx_attempts(&tx_attempts);
+   uesb_get_tx_attempts(&tx_attempts);
     NRF_GPIO->OUTCLR = 0xFUL << 12;
     NRF_GPIO->OUTSET = (tx_attempts & 0x0F) << 12;
 }
@@ -65,9 +67,9 @@
     
     uesb_init(&uesb_config);
 
-    uesb_set_address(UESB_ADDRESS_PIPE0, rx_addr_p0);
-    uesb_set_address(UESB_ADDRESS_PIPE1, rx_addr_p1);
-    uesb_set_address(UESB_ADDRESS_PIPE2, &rx_addr_p2);
+    nrf_esb_set_base_address_0(rx_addr_p0);
+    nrf_esb_set_base_address_1(rx_addr_p1);
+    //nrf_esb_set_base_address_2(&rx_addr_p2);
 
     tx_payload.length  = 8;
     tx_payload.pipe    = 0;
diff -r a01a54c0dc90 -r 66f95e364222 mbed-os.lib
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os.lib	Thu Feb 04 10:36:44 2021 +0000
@@ -0,0 +1,1 @@
+https://github.com/ARMmbed/mbed-os/#bfde5aa1e74802771eaeacfa74789f71677325cb
diff -r a01a54c0dc90 -r 66f95e364222 mbed.bld
--- a/mbed.bld	Mon Mar 23 04:09:41 2015 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +0,0 @@
-http://mbed.org/users/mbed_official/code/mbed/builds/487b796308b0
\ No newline at end of file
diff -r a01a54c0dc90 -r 66f95e364222 micro_esb.c
--- a/micro_esb.c	Mon Mar 23 04:09:41 2015 +0000
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,871 +0,0 @@
-/* Copyright (c) 2014 Nordic Semiconductor. All Rights Reserved.
- *
- * The information contained herein is property of Nordic Semiconductor ASA.
- * Terms and conditions of usage are described in detail in NORDIC
- * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
- *
- * Licensees are granted free, non-transferable use of the information. NO
- * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
- * the file.
- *
- */
-
-#include "micro_esb.h"
-#include "uesb_error_codes.h"
-//#include "nrf_gpio.h"
-#include <string.h>
-
-
-static uesb_event_handler_t     m_event_handler;
-
-// RF parameters
-static uesb_config_t            m_config_local;
-
-// TX FIFO
-static uesb_payload_t           m_tx_fifo_payload[UESB_CORE_TX_FIFO_SIZE];
-static uesb_payload_tx_fifo_t   m_tx_fifo;
-
-// RX FIFO
-static uesb_payload_t           m_rx_fifo_payload[UESB_CORE_RX_FIFO_SIZE];
-static uesb_payload_rx_fifo_t   m_rx_fifo;
-
-static  uint8_t                 m_tx_payload_buffer[UESB_CORE_MAX_PAYLOAD_LENGTH + 2];
-static  uint8_t                 m_rx_payload_buffer[UESB_CORE_MAX_PAYLOAD_LENGTH + 2];
-
-// Run time variables
-static volatile uint32_t        m_interrupt_flags       = 0;
-static uint32_t                 m_pid                   = 0;
-static volatile uint32_t        m_retransmits_remaining;
-static volatile uint32_t        m_last_tx_attempts;
-static volatile uint8_t         m_last_rx_packet_pid = 0xFF;
-static volatile uint32_t        m_last_rx_packet_crc = 0xFFFFFFFF;
-static volatile uint32_t        m_wait_for_ack_timeout_us;
-
-static uesb_payload_t           *current_payload;
-
-static uesb_mainstate_t         m_uesb_mainstate        = UESB_STATE_UNINITIALIZED;
-
-// Constant parameters
-#define                         RX_WAIT_FOR_ACK_TIMEOUT_US_2MBPS   48   // Smallest reliable value - 43
-#define                         RX_WAIT_FOR_ACK_TIMEOUT_US_1MBPS   64   // Smallest reliable value - 59
-#define                         RX_WAIT_FOR_ACK_TIMEOUT_US_250KBPS 250
-
-// Macros
-#define                         DISABLE_RF_IRQ      NVIC_DisableIRQ(RADIO_IRQn)
-#define                         ENABLE_RF_IRQ       NVIC_EnableIRQ(RADIO_IRQn)
-
-#define                         RADIO_SHORTS_COMMON ( RADIO_SHORTS_READY_START_Msk | RADIO_SHORTS_END_DISABLE_Msk | \
-                                                      RADIO_SHORTS_ADDRESS_RSSISTART_Msk | RADIO_SHORTS_DISABLED_RSSISTOP_Msk )
-
-// These function pointers are changed dynamically, depending on protocol configuration and state
-static void (*on_radio_disabled)(void) = 0;
-static void (*on_radio_end)(void) = 0;
-static void (*update_rf_payload_format)(uint32_t payload_length) = 0;
-
-// The following functions are assigned to the function pointers above
-static void on_radio_disabled_esb_dpl_tx_noack(void);
-static void on_radio_disabled_esb_dpl_tx(void);
-static void on_radio_disabled_esb_dpl_tx_wait_for_ack(void);
-static void on_radio_disabled_esb_dpl_rx(void);
-static void on_radio_disabled_esb_dpl_rx_ack(void);
-
-static void on_radio_end_sb_tx(void);
-static void on_radio_end_sb_rx(void);
-
-static void update_rf_payload_format_esb_dpl(uint32_t payload_length)
-{
-#if(UESB_CORE_MAX_PAYLOAD_LENGTH <= 32)
-    NRF_RADIO->PCNF0 = (0 << RADIO_PCNF0_S0LEN_Pos) | (6 << RADIO_PCNF0_LFLEN_Pos) | (3 << RADIO_PCNF0_S1LEN_Pos);
-#else
-    NRF_RADIO->PCNF0 = (0 << RADIO_PCNF0_S0LEN_Pos) | (8 << RADIO_PCNF0_LFLEN_Pos) | (3 << RADIO_PCNF0_S1LEN_Pos);
-#endif
-    NRF_RADIO->PCNF1 = (RADIO_PCNF1_WHITEEN_Disabled        << RADIO_PCNF1_WHITEEN_Pos) |
-                       (RADIO_PCNF1_ENDIAN_Big              << RADIO_PCNF1_ENDIAN_Pos)  |
-                       ((m_config_local.rf_addr_length - 1) << RADIO_PCNF1_BALEN_Pos)   |
-                       (0                                   << RADIO_PCNF1_STATLEN_Pos) |
-                       (UESB_CORE_MAX_PAYLOAD_LENGTH        << RADIO_PCNF1_MAXLEN_Pos);
-}
-
-static void update_rf_payload_format_esb(uint32_t payload_length)
-{
-    NRF_RADIO->PCNF0 = (1 << RADIO_PCNF0_S0LEN_Pos) | (0 << RADIO_PCNF0_LFLEN_Pos) | (1 << RADIO_PCNF0_S1LEN_Pos);
-    NRF_RADIO->PCNF1 = (RADIO_PCNF1_WHITEEN_Disabled        << RADIO_PCNF1_WHITEEN_Pos) |
-                       (RADIO_PCNF1_ENDIAN_Big              << RADIO_PCNF1_ENDIAN_Pos)  |
-                       ((m_config_local.rf_addr_length - 1) << RADIO_PCNF1_BALEN_Pos)   |
-                       (payload_length                      << RADIO_PCNF1_STATLEN_Pos) |
-                       (payload_length                      << RADIO_PCNF1_MAXLEN_Pos);
-}
-
-static void update_rf_payload_format_sb(uint32_t payload_length)
-{
-    NRF_RADIO->PCNF0 = (0 << RADIO_PCNF0_S0LEN_Pos) | (0 << RADIO_PCNF0_LFLEN_Pos) | (0 << RADIO_PCNF0_S1LEN_Pos);
-    NRF_RADIO->PCNF1 = (RADIO_PCNF1_WHITEEN_Disabled        << RADIO_PCNF1_WHITEEN_Pos) |
-                       (RADIO_PCNF1_ENDIAN_Big              << RADIO_PCNF1_ENDIAN_Pos)  |
-                       ((m_config_local.rf_addr_length - 1) << RADIO_PCNF1_BALEN_Pos)   |
-                       (payload_length                      << RADIO_PCNF1_STATLEN_Pos) |
-                       (payload_length                      << RADIO_PCNF1_MAXLEN_Pos);
-}
-
-// Function that swaps the bits within each byte in a uint32. Used to convert from nRF24L type addressing to nRF51 type addressing
-static uint32_t bytewise_bit_swap(uint32_t inp)
-{
-    inp = (inp & 0xF0F0F0F0) >> 4 | (inp & 0x0F0F0F0F) << 4;
-    inp = (inp & 0xCCCCCCCC) >> 2 | (inp & 0x33333333) << 2;
-    return (inp & 0xAAAAAAAA) >> 1 | (inp & 0x55555555) << 1;
-}
-
-static void update_radio_parameters()
-{
-    // Protocol
-    switch(m_config_local.protocol)
-    {
-        case UESB_PROTOCOL_ESB_DPL:
-            update_rf_payload_format = update_rf_payload_format_esb_dpl;
-            break;
-        case UESB_PROTOCOL_ESB:
-            update_rf_payload_format = update_rf_payload_format_esb;
-            break;
-        case UESB_PROTOCOL_SB:
-            update_rf_payload_format = update_rf_payload_format_sb;
-            on_radio_end = (m_config_local.mode == UESB_MODE_PTX ? on_radio_end_sb_tx : on_radio_end_sb_rx);
-            break;
-    }
-    // TX power
-    NRF_RADIO->TXPOWER   = m_config_local.tx_output_power   << RADIO_TXPOWER_TXPOWER_Pos;
-
-    // RF bitrate
-    NRF_RADIO->MODE      = m_config_local.bitrate           << RADIO_MODE_MODE_Pos;
-    switch(m_config_local.bitrate)
-    {
-        case UESB_BITRATE_2MBPS:
-            m_wait_for_ack_timeout_us = RX_WAIT_FOR_ACK_TIMEOUT_US_2MBPS;
-            break;
-        case UESB_BITRATE_1MBPS:
-            m_wait_for_ack_timeout_us = RX_WAIT_FOR_ACK_TIMEOUT_US_1MBPS;
-            break;
-        case UESB_BITRATE_250KBPS:
-            m_wait_for_ack_timeout_us = RX_WAIT_FOR_ACK_TIMEOUT_US_250KBPS;
-            break;
-    }
-
-    // CRC configuration
-    NRF_RADIO->CRCCNF    = m_config_local.crc               << RADIO_CRCCNF_LEN_Pos;
-    if(m_config_local.crc == RADIO_CRCCNF_LEN_Two)
-    {
-        NRF_RADIO->CRCINIT = 0xFFFFUL;      // Initial value
-        NRF_RADIO->CRCPOLY = 0x11021UL;     // CRC poly: x^16+x^12^x^5+1
-    }
-    else if(m_config_local.crc == RADIO_CRCCNF_LEN_One)
-    {
-        NRF_RADIO->CRCINIT = 0xFFUL;        // Initial value
-        NRF_RADIO->CRCPOLY = 0x107UL;       // CRC poly: x^8+x^2^x^1+1
-    }
-
-    // Packet format
-    update_rf_payload_format(m_config_local.payload_length);
-
-    // Radio address config
-    NRF_RADIO->PREFIX0 = bytewise_bit_swap(m_config_local.rx_address_p3 << 24 | m_config_local.rx_address_p2 << 16 | m_config_local.rx_address_p1[0] << 8 | m_config_local.rx_address_p0[0]);
-    NRF_RADIO->PREFIX1 = bytewise_bit_swap(m_config_local.rx_address_p7 << 24 | m_config_local.rx_address_p6 << 16 | m_config_local.rx_address_p5 << 8 | m_config_local.rx_address_p4);
-    NRF_RADIO->BASE0   = bytewise_bit_swap(m_config_local.rx_address_p0[1] << 24 | m_config_local.rx_address_p0[2] << 16 | m_config_local.rx_address_p0[3] << 8 | m_config_local.rx_address_p0[4]);
-    NRF_RADIO->BASE1   = bytewise_bit_swap(m_config_local.rx_address_p1[1] << 24 | m_config_local.rx_address_p1[2] << 16 | m_config_local.rx_address_p1[3] << 8 | m_config_local.rx_address_p1[4]);
-}
-
-static void initialize_fifos()
-{
-    m_tx_fifo.entry_point = 0;
-    m_tx_fifo.exit_point  = 0;
-    m_tx_fifo.count       = 0;
-    for(int i = 0; i < UESB_CORE_TX_FIFO_SIZE; i++)
-    {
-        m_tx_fifo.payload_ptr[i] = &m_tx_fifo_payload[i];
-    }
-
-    m_rx_fifo.entry_point = 0;
-    m_rx_fifo.exit_point  = 0;
-    m_rx_fifo.count       = 0;
-    for(int i = 0; i < UESB_CORE_RX_FIFO_SIZE; i++)
-    {
-        m_rx_fifo.payload_ptr[i] = &m_rx_fifo_payload[i];
-    }
-}
-
-static void tx_fifo_remove_last()
-{
-    if(m_tx_fifo.count > 0)
-    {
-        DISABLE_RF_IRQ;
-        m_tx_fifo.count--;
-        m_tx_fifo.exit_point++;
-        if(m_tx_fifo.exit_point >= UESB_CORE_TX_FIFO_SIZE) m_tx_fifo.exit_point = 0;
-        ENABLE_RF_IRQ;
-    }
-}
-
-static bool rx_fifo_push_rfbuf(uint8_t pipe)
-{
-    if(m_rx_fifo.count < UESB_CORE_RX_FIFO_SIZE)
-    {
-        if(m_config_local.protocol == UESB_PROTOCOL_ESB_DPL)
-        {
-            if(m_rx_payload_buffer[0] > UESB_CORE_MAX_PAYLOAD_LENGTH) return false;
-            m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->length = m_rx_payload_buffer[0];
-        }
-        else
-        {
-            m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->length = m_config_local.payload_length;
-        }
-        if(m_config_local.protocol == UESB_PROTOCOL_SB)
-        {
-            memcpy(m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->data, &m_rx_payload_buffer[0], m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->length);
-        }
-        else
-        {
-            memcpy(m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->data, &m_rx_payload_buffer[2], m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->length);
-        }
-        m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->pipe = pipe;
-        m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->rssi = NRF_RADIO->RSSISAMPLE;
-        if(++m_rx_fifo.entry_point >= UESB_CORE_RX_FIFO_SIZE) m_rx_fifo.entry_point = 0;
-        m_rx_fifo.count++;
-        return true;
-    }
-    return false;
-}
-
-static void sys_timer_init()
-{
-    // Configure the system timer with a 1 MHz base frequency
-    UESB_SYS_TIMER->PRESCALER = 4;
-    UESB_SYS_TIMER->BITMODE   = TIMER_BITMODE_BITMODE_16Bit;
-    UESB_SYS_TIMER->SHORTS    = TIMER_SHORTS_COMPARE1_CLEAR_Msk | TIMER_SHORTS_COMPARE1_STOP_Msk;
-}
-
-static void ppi_init()
-{
-    NRF_PPI->CH[UESB_PPI_TIMER_START].EEP = (uint32_t)&NRF_RADIO->EVENTS_READY;
-    NRF_PPI->CH[UESB_PPI_TIMER_START].TEP = (uint32_t)&UESB_SYS_TIMER->TASKS_START;
-    NRF_PPI->CH[UESB_PPI_TIMER_STOP].EEP =  (uint32_t)&NRF_RADIO->EVENTS_ADDRESS;
-    NRF_PPI->CH[UESB_PPI_TIMER_STOP].TEP =  (uint32_t)&UESB_SYS_TIMER->TASKS_STOP;
-    NRF_PPI->CH[UESB_PPI_RX_TIMEOUT].EEP = (uint32_t)&UESB_SYS_TIMER->EVENTS_COMPARE[0];
-    NRF_PPI->CH[UESB_PPI_RX_TIMEOUT].TEP = (uint32_t)&NRF_RADIO->TASKS_DISABLE;
-    NRF_PPI->CH[UESB_PPI_TX_START].EEP = (uint32_t)&UESB_SYS_TIMER->EVENTS_COMPARE[1];
-    NRF_PPI->CH[UESB_PPI_TX_START].TEP = (uint32_t)&NRF_RADIO->TASKS_TXEN;
-}
-
-uint32_t uesb_init(uesb_config_t *parameters)
-{
-    if(m_uesb_mainstate != UESB_STATE_UNINITIALIZED) return UESB_ERROR_ALREADY_INITIALIZED;
-    m_event_handler = parameters->event_handler;
-    memcpy(&m_config_local, parameters, sizeof(uesb_config_t));
-
-    m_interrupt_flags    = 0;
-    m_pid                = 0;
-    m_last_rx_packet_pid = 0xFF;
-    m_last_rx_packet_crc = 0xFFFFFFFF;
-
-    update_radio_parameters();
-
-    initialize_fifos();
-
-    sys_timer_init();
-
-    ppi_init();
-
-    NVIC_SetPriority(RADIO_IRQn, m_config_local.radio_irq_priority & 0x03);
-
-    //m_uesb_initialized = true;
-    m_uesb_mainstate = UESB_STATE_IDLE;
-
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_disable(void)
-{
-    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
-    NRF_PPI->CHENCLR = (1 << UESB_PPI_TIMER_START) | (1 << UESB_PPI_TIMER_STOP) | (1 << UESB_PPI_RX_TIMEOUT) | (1 << UESB_PPI_TX_START);
-    m_uesb_mainstate = UESB_STATE_UNINITIALIZED;
-    return UESB_SUCCESS;
-}
-
-static void start_tx_transaction()
-{
-    bool ack;
-    m_last_tx_attempts = 1;
-    // Prepare the payload
-    current_payload = m_tx_fifo.payload_ptr[m_tx_fifo.exit_point];
-    m_pid = (m_pid + 1) % 4;
-    switch(m_config_local.protocol)
-    {
-        case UESB_PROTOCOL_SB:
-            update_rf_payload_format(current_payload->length);
-            memcpy(&m_tx_payload_buffer[0], current_payload->data, current_payload->length);
-            NRF_RADIO->SHORTS   = RADIO_SHORTS_READY_START_Msk;
-            NRF_RADIO->INTENSET = RADIO_INTENSET_END_Msk;
-            on_radio_disabled   = on_radio_disabled_esb_dpl_tx_noack;
-            m_uesb_mainstate    = UESB_STATE_PTX_TX;
-            break;
-
-        case UESB_PROTOCOL_ESB:
-            update_rf_payload_format(current_payload->length);
-            m_tx_payload_buffer[0] = 0xCC | m_pid;
-            m_tx_payload_buffer[1] = 0;
-            memcpy(&m_tx_payload_buffer[2], current_payload->data, current_payload->length);
-
-            NRF_RADIO->SHORTS   = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_RXEN_Msk;
-            NRF_RADIO->INTENSET = RADIO_INTENSET_DISABLED_Msk | RADIO_INTENSET_READY_Msk;
-
-            // Configure the retransmit counter
-            m_retransmits_remaining = m_config_local.retransmit_count;
-            on_radio_disabled = on_radio_disabled_esb_dpl_tx;
-            m_uesb_mainstate = UESB_STATE_PTX_TX_ACK;
-            break;
-
-        case UESB_PROTOCOL_ESB_DPL:
-            ack = current_payload->noack == 0 || m_config_local.dynamic_ack_enabled == 0;
-            m_tx_payload_buffer[0] = current_payload->length;
-            m_tx_payload_buffer[1] = m_pid << 1 | ((current_payload->noack == 0 && m_config_local.dynamic_ack_enabled) ? 0x01 : 0x00);
-            memcpy(&m_tx_payload_buffer[2], current_payload->data, current_payload->length);
-            if(ack)
-            {
-                NRF_RADIO->SHORTS   = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_RXEN_Msk;
-                NRF_RADIO->INTENSET = RADIO_INTENSET_DISABLED_Msk | RADIO_INTENSET_READY_Msk;
-
-                // Configure the retransmit counter
-                m_retransmits_remaining = m_config_local.retransmit_count;
-                on_radio_disabled = on_radio_disabled_esb_dpl_tx;
-                m_uesb_mainstate = UESB_STATE_PTX_TX_ACK;
-            }
-            else
-            {
-                NRF_RADIO->SHORTS   = RADIO_SHORTS_COMMON;
-                NRF_RADIO->INTENSET = RADIO_INTENSET_DISABLED_Msk;
-                on_radio_disabled   = on_radio_disabled_esb_dpl_tx_noack;
-                m_uesb_mainstate    = UESB_STATE_PTX_TX;
-            }
-            break;
-    }
-
-    NRF_RADIO->TXADDRESS = current_payload->pipe;
-    NRF_RADIO->RXADDRESSES = 1 << current_payload->pipe;
-
-    NRF_RADIO->FREQUENCY = m_config_local.rf_channel;
-
-    NRF_RADIO->PACKETPTR = (uint32_t)m_tx_payload_buffer;
-
-    NVIC_ClearPendingIRQ(RADIO_IRQn);
-    NVIC_EnableIRQ(RADIO_IRQn);
-
-    NRF_RADIO->EVENTS_ADDRESS = NRF_RADIO->EVENTS_PAYLOAD = NRF_RADIO->EVENTS_DISABLED = 0;
-    DEBUG_PIN_SET(DEBUGPIN4);
-    NRF_RADIO->TASKS_TXEN  = 1;
-}
-
-static uint32_t write_tx_payload(uesb_payload_t *payload, bool noack) // ~50us @ 61 bytes SB
-{
-    if(m_uesb_mainstate == UESB_STATE_UNINITIALIZED) return UESB_ERROR_NOT_INITIALIZED;
-    if(m_tx_fifo.count >= UESB_CORE_TX_FIFO_SIZE) return UESB_ERROR_TX_FIFO_FULL;
-
-    DISABLE_RF_IRQ;
-    if(noack && m_config_local.dynamic_ack_enabled) payload->noack = 1;
-    else payload->noack = 0;
-    memcpy(m_tx_fifo.payload_ptr[m_tx_fifo.entry_point], payload, sizeof(uesb_payload_t));
-    m_tx_fifo.entry_point++;
-    if(m_tx_fifo.entry_point >= UESB_CORE_TX_FIFO_SIZE) m_tx_fifo.entry_point = 0;
-    m_tx_fifo.count++;
-    ENABLE_RF_IRQ;
-
-    if(m_config_local.tx_mode == UESB_TXMODE_AUTO && m_uesb_mainstate == UESB_STATE_IDLE)
-    {
-        start_tx_transaction();
-    }
-
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_write_tx_payload(uesb_payload_t *payload)
-{
-    return write_tx_payload(payload, false);
-}
-
-uint32_t uesb_write_tx_payload_noack(uesb_payload_t *payload)
-{
-    if(m_config_local.dynamic_ack_enabled == 0) return UESB_ERROR_DYN_ACK_NOT_ENABLED;
-    return write_tx_payload(payload, true);
-}
-
-uint32_t uesb_write_ack_payload(uesb_payload_t *payload)
-{
-    if(m_uesb_mainstate == UESB_STATE_UNINITIALIZED) return UESB_ERROR_NOT_INITIALIZED;
-    if((m_uesb_mainstate != UESB_STATE_PRX) &&
-       (m_uesb_mainstate != UESB_STATE_PRX_SEND_ACK) &&
-       (m_uesb_mainstate != UESB_STATE_PRX_SEND_ACK_PAYLOAD))
-    {
-        return UESB_ERROR_NOT_IN_RX_MODE;
-    }
-    if(m_tx_fifo.count >= UESB_CORE_TX_FIFO_SIZE) return UESB_ERROR_TX_FIFO_FULL;
-
-    DISABLE_RF_IRQ;
-    memcpy(m_tx_fifo.payload_ptr[m_tx_fifo.entry_point], payload, sizeof(uesb_payload_t));
-    m_tx_fifo.entry_point++;
-    if(m_tx_fifo.entry_point >= UESB_CORE_TX_FIFO_SIZE) m_tx_fifo.entry_point = 0;
-    m_tx_fifo.count++;
-    ENABLE_RF_IRQ;
-
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_read_rx_payload(uesb_payload_t *payload)
-{
-    if(m_uesb_mainstate == UESB_STATE_UNINITIALIZED) return UESB_ERROR_NOT_INITIALIZED;
-    if(m_rx_fifo.count == 0) return UESB_ERROR_RX_FIFO_EMPTY;
-
-    DISABLE_RF_IRQ;
-    payload->length = m_rx_fifo.payload_ptr[m_rx_fifo.exit_point]->length;
-    payload->pipe   = m_rx_fifo.payload_ptr[m_rx_fifo.exit_point]->pipe;
-    payload->rssi   = m_rx_fifo.payload_ptr[m_rx_fifo.exit_point]->rssi;
-    memcpy(payload->data, m_rx_fifo.payload_ptr[m_rx_fifo.exit_point]->data, payload->length);
-    if(++m_rx_fifo.exit_point >= UESB_CORE_RX_FIFO_SIZE) m_rx_fifo.exit_point = 0;
-    m_rx_fifo.count--;
-    ENABLE_RF_IRQ;
-
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_start_tx()
-{
-    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
-    if(m_tx_fifo.count == 0) return UESB_ERROR_TX_FIFO_EMPTY;
-    start_tx_transaction();
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_start_rx(void)
-{
-    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
-
-    NRF_RADIO->INTENCLR = 0xFFFFFFFF;
-    NRF_RADIO->EVENTS_DISABLED = 0;
-    on_radio_disabled = on_radio_disabled_esb_dpl_rx;
-    switch(m_config_local.protocol)
-    {
-        case UESB_PROTOCOL_SB:
-            NRF_RADIO->SHORTS      = RADIO_SHORTS_READY_START_Msk | RADIO_SHORTS_END_START_Msk;
-            NRF_RADIO->INTENSET    = RADIO_INTENSET_END_Msk;
-            m_uesb_mainstate       = UESB_STATE_PRX;
-            break;
-        case UESB_PROTOCOL_ESB:
-            NRF_RADIO->SHORTS      = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_TXEN_Msk;
-            NRF_RADIO->INTENSET    = RADIO_INTENSET_DISABLED_Msk;
-            m_uesb_mainstate       = UESB_STATE_PRX;
-            break;
-        case UESB_PROTOCOL_ESB_DPL:
-            NRF_RADIO->SHORTS      = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_TXEN_Msk;
-            NRF_RADIO->INTENSET    = RADIO_INTENSET_DISABLED_Msk;
-            m_uesb_mainstate       = UESB_STATE_PRX;
-            break;
-    }
-
-    NRF_RADIO->RXADDRESSES = m_config_local.rx_pipes_enabled;
-
-    NRF_RADIO->FREQUENCY = m_config_local.rf_channel;
-
-    NRF_RADIO->PACKETPTR = (uint32_t)m_rx_payload_buffer;
-
-    NVIC_ClearPendingIRQ(RADIO_IRQn);
-    NVIC_EnableIRQ(RADIO_IRQn);
-
-    NRF_RADIO->EVENTS_ADDRESS = NRF_RADIO->EVENTS_PAYLOAD = NRF_RADIO->EVENTS_DISABLED = 0;
-    NRF_RADIO->TASKS_RXEN  = 1;
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_stop_rx(void)
-{
-    if((m_uesb_mainstate == UESB_STATE_PRX) || (m_uesb_mainstate == UESB_STATE_PRX_SEND_ACK_PAYLOAD))
-    {
-        NRF_RADIO->SHORTS = 0;
-        NRF_RADIO->INTENCLR = 0xFFFFFFFF;
-        on_radio_disabled = NULL;
-        NRF_RADIO->EVENTS_DISABLED = 0;
-        NRF_RADIO->TASKS_DISABLE = 1;
-        while(NRF_RADIO->EVENTS_DISABLED == 0);
-        m_uesb_mainstate = UESB_STATE_IDLE;
-        return UESB_SUCCESS;
-    }
-    return UESB_ERROR_NOT_IN_RX_MODE;
-}
-
-uint32_t uesb_get_tx_attempts(uint32_t *attempts)
-{
-    if(m_uesb_mainstate == UESB_STATE_UNINITIALIZED) return UESB_ERROR_NOT_INITIALIZED;
-    *attempts = m_last_tx_attempts;
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_flush_tx(void)
-{
-    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
-    DISABLE_RF_IRQ;
-    m_tx_fifo.count = 0;
-    m_tx_fifo.entry_point = m_tx_fifo.exit_point = 0;
-    ENABLE_RF_IRQ;
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_flush_rx(void)
-{
-    DISABLE_RF_IRQ;
-    m_rx_fifo.count = 0;
-    m_rx_fifo.entry_point = 0;
-    ENABLE_RF_IRQ;
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_get_clear_interrupts(uint32_t *interrupts)
-{
-    DISABLE_RF_IRQ;
-    *interrupts = m_interrupt_flags;
-    m_interrupt_flags = 0;
-    ENABLE_RF_IRQ;
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_set_address(uesb_address_type_t address, const uint8_t *data_ptr)
-{
-    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
-    switch(address)
-    {
-        case UESB_ADDRESS_PIPE0:
-            memcpy(m_config_local.rx_address_p0, data_ptr, m_config_local.rf_addr_length);
-            break;
-        case UESB_ADDRESS_PIPE1:
-            memcpy(m_config_local.rx_address_p1, data_ptr, m_config_local.rf_addr_length);
-            break;
-        case UESB_ADDRESS_PIPE2:
-            m_config_local.rx_address_p2 = *data_ptr;
-            break;
-        case UESB_ADDRESS_PIPE3:
-            m_config_local.rx_address_p3 = *data_ptr;
-            break;
-        case UESB_ADDRESS_PIPE4:
-            m_config_local.rx_address_p4 = *data_ptr;
-            break;
-        case UESB_ADDRESS_PIPE5:
-            m_config_local.rx_address_p5 = *data_ptr;
-            break;
-        case UESB_ADDRESS_PIPE6:
-            m_config_local.rx_address_p6 = *data_ptr;
-            break;
-        case UESB_ADDRESS_PIPE7:
-            m_config_local.rx_address_p7 = *data_ptr;
-            break;
-        default:
-            return UESB_ERROR_INVALID_PARAMETERS;
-    }
-    update_radio_parameters();
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_set_rf_channel(uint32_t channel)
-{
-    if(channel > 125) return UESB_ERROR_INVALID_PARAMETERS;
-    m_config_local.rf_channel = channel;
-    return UESB_SUCCESS;
-}
-
-uint32_t uesb_set_tx_power(uesb_tx_power_t tx_output_power)
-{
-    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
-    if ( m_config_local.tx_output_power == tx_output_power ) return UESB_SUCCESS;
-    m_config_local.tx_output_power = tx_output_power;
-    update_radio_parameters();
-    return UESB_SUCCESS;
-}
-
-void RADIO_IRQHandler()
-{
-    if(NRF_RADIO->EVENTS_READY && (NRF_RADIO->INTENSET & RADIO_INTENSET_READY_Msk))
-    {
-        NRF_RADIO->EVENTS_READY = 0;
-
-        DEBUG_PIN_SET(DEBUGPIN1);
-    }
-
-    if(NRF_RADIO->EVENTS_END && (NRF_RADIO->INTENSET & RADIO_INTENSET_END_Msk))
-    {
-        NRF_RADIO->EVENTS_END = 0;
-
-        DEBUG_PIN_SET(DEBUGPIN2);
-
-        // Call the correct on_radio_end function, depending on the current protocol state
-        if(on_radio_end)
-        {
-            on_radio_end();
-        }
-    }
-
-    if(NRF_RADIO->EVENTS_DISABLED && (NRF_RADIO->INTENSET & RADIO_INTENSET_DISABLED_Msk))
-    {
-        NRF_RADIO->EVENTS_DISABLED = 0;
-
-        DEBUG_PIN_SET(DEBUGPIN3);
-
-        // Call the correct on_radio_disable function, depending on the current protocol state
-        if(on_radio_disabled)
-        {
-            on_radio_disabled();
-        }
-    }
-
-    DEBUG_PIN_CLR(DEBUGPIN1);
-    DEBUG_PIN_CLR(DEBUGPIN2);
-    DEBUG_PIN_CLR(DEBUGPIN3);
-    DEBUG_PIN_CLR(DEBUGPIN4);
-}
-
-static void on_radio_disabled_esb_dpl_tx_noack()
-{
-    m_interrupt_flags |= UESB_INT_TX_SUCCESS_MSK;
-    tx_fifo_remove_last();
-
-    if(m_tx_fifo.count == 0)
-    {
-        m_uesb_mainstate = UESB_STATE_IDLE;
-	if(m_event_handler != 0) m_event_handler();
-    }
-    else
-    {
-        if(m_event_handler != 0) m_event_handler();
-        start_tx_transaction();
-    }
-}
-
-static void on_radio_disabled_esb_dpl_tx()
-{
-    // Remove the DISABLED -> RXEN shortcut, to make sure the radio stays disabled after the RX window
-    NRF_RADIO->SHORTS           = RADIO_SHORTS_COMMON;
-
-    // Make sure the timer is started the next time the radio is ready,
-    // and that it will disable the radio automatically if no packet is received by the time defined in m_wait_for_ack_timeout_us
-    UESB_SYS_TIMER->CC[0]       = m_wait_for_ack_timeout_us;
-    UESB_SYS_TIMER->CC[1]       = m_config_local.retransmit_delay - 130;
-    UESB_SYS_TIMER->TASKS_CLEAR = 1;
-    UESB_SYS_TIMER->EVENTS_COMPARE[0] = 0;
-    UESB_SYS_TIMER->EVENTS_COMPARE[1] = 0;
-    NRF_PPI->CHENSET            = (1 << UESB_PPI_TIMER_START) | (1 << UESB_PPI_RX_TIMEOUT) | (1 << UESB_PPI_TIMER_STOP);
-    NRF_PPI->CHENCLR            = (1 << UESB_PPI_TX_START);
-    NRF_RADIO->EVENTS_END       = 0;
-    if(m_config_local.protocol == UESB_PROTOCOL_ESB)
-    {
-        update_rf_payload_format(0);
-    }
-    NRF_RADIO->PACKETPTR        = (uint32_t)m_rx_payload_buffer;
-    on_radio_disabled           = on_radio_disabled_esb_dpl_tx_wait_for_ack;
-    m_uesb_mainstate            = UESB_STATE_PTX_RX_ACK;
-}
-
-static void on_radio_disabled_esb_dpl_tx_wait_for_ack()
-{
-    // This marks the completion of a TX_RX sequence (TX with ACK)
-
-    // Make sure the timer will not deactivate the radio if a packet is received
-    NRF_PPI->CHENCLR = (1 << UESB_PPI_TIMER_START) | (1 << UESB_PPI_RX_TIMEOUT) | (1 << UESB_PPI_TIMER_STOP);
-
-    // If the radio has received a packet and the CRC status is OK
-    if(NRF_RADIO->EVENTS_END && NRF_RADIO->CRCSTATUS != 0)
-    {
-        UESB_SYS_TIMER->TASKS_STOP = 1;
-        NRF_PPI->CHENCLR = (1 << UESB_PPI_TX_START);
-        m_interrupt_flags |= UESB_INT_TX_SUCCESS_MSK;
-        m_last_tx_attempts = m_config_local.retransmit_count - m_retransmits_remaining + 1;
-        tx_fifo_remove_last();
-        if(m_rx_payload_buffer[0] > 0)
-        {
-            if(rx_fifo_push_rfbuf((uint8_t)NRF_RADIO->TXADDRESS))
-            {
-                m_interrupt_flags |= UESB_INT_RX_DR_MSK;
-            }
-        }
-
-        if((m_tx_fifo.count == 0) || (m_config_local.tx_mode == UESB_TXMODE_MANUAL))
-	{
-            m_uesb_mainstate = UESB_STATE_IDLE;
-	    if(m_event_handler != 0) m_event_handler();
-        }
-        else
-	{
-            if(m_event_handler != 0) m_event_handler();
-            start_tx_transaction();
-	}
-    }
-    else
-    {
-        if(m_retransmits_remaining-- == 0)
-        {
-            UESB_SYS_TIMER->TASKS_STOP = 1;
-            NRF_PPI->CHENCLR = (1 << UESB_PPI_TX_START);
-            // All retransmits are expended, and the TX operation is suspended
-            m_last_tx_attempts = m_config_local.retransmit_count + 1;
-            m_interrupt_flags |= UESB_INT_TX_FAILED_MSK;
-
-            m_uesb_mainstate = UESB_STATE_IDLE;
-	    if(m_event_handler != 0) m_event_handler();
-        }
-        else
-        {
-            // We still have more retransmits left, and we should enter TX mode again as soon as the system timer reaches CC[1]
-            NRF_RADIO->SHORTS = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_RXEN_Msk;
-            update_rf_payload_format(current_payload->length);
-            NRF_RADIO->PACKETPTR = (uint32_t)m_tx_payload_buffer;
-            on_radio_disabled = on_radio_disabled_esb_dpl_tx;
-            m_uesb_mainstate = UESB_STATE_PTX_TX_ACK;
-            UESB_SYS_TIMER->TASKS_START = 1;
-            NRF_PPI->CHENSET = (1 << UESB_PPI_TX_START);
-            if(UESB_SYS_TIMER->EVENTS_COMPARE[1])
-            {
-                NRF_RADIO->TASKS_TXEN = 1;
-            }                 
-        }
-    }
-}
-
-static void on_radio_disabled_esb_dpl_rx(void)
-{
-    bool send_ack = false;
-    bool set_rx_interrupt = false;
-    if(NRF_RADIO->CRCSTATUS != 0 && m_rx_fifo.count < UESB_CORE_RX_FIFO_SIZE)
-    {
-        send_ack = true;
-    }
-    if(send_ack)
-    {
-        NRF_RADIO->SHORTS = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_RXEN_Msk;
-
-        // For a packet to be considered new (and not a retransmit) the PID or the CRC has to be different
-        if(NRF_RADIO->RXCRC != m_last_rx_packet_crc || (m_rx_payload_buffer[1] >> 1) != m_last_rx_packet_pid)
-        {
-	    if((m_uesb_mainstate == UESB_STATE_PRX_SEND_ACK_PAYLOAD) && (m_tx_fifo.count > 0))
-            {
-                // It is assumed that the last ACK payload was recieved.
-                if(++m_tx_fifo.exit_point >= UESB_CORE_RX_FIFO_SIZE) m_tx_fifo.exit_point = 0;
-                m_tx_fifo.count--;
-
-                // ACK payloads also require TX_DS (page 40 of the 'nRF24LE1_Product_Specification_rev1_6.pdf').
-                m_interrupt_flags |= UESB_INT_TX_SUCCESS_MSK;
-            }
-
-            set_rx_interrupt = true;
-            m_last_rx_packet_pid = m_rx_payload_buffer[1] >> 1;
-            m_last_rx_packet_crc = NRF_RADIO->RXCRC;
-        }
-
-        if(m_config_local.protocol == UESB_PROTOCOL_ESB_DPL)
-        {
-	    if(m_tx_fifo.count > 0)
-	    {
-                current_payload = m_tx_fifo.payload_ptr[m_tx_fifo.exit_point];
-
-                update_rf_payload_format(current_payload->length);
-                m_tx_payload_buffer[0] = current_payload->length;
-                memcpy(&m_tx_payload_buffer[2], current_payload->data, current_payload->length);
-
-		m_uesb_mainstate = UESB_STATE_PRX_SEND_ACK_PAYLOAD;
-	    }
-            else
-	    {
-                update_rf_payload_format(0);
-                m_tx_payload_buffer[0] = 0;
-
-                m_uesb_mainstate = UESB_STATE_PRX_SEND_ACK;
-            }
-
-            m_tx_payload_buffer[1] = m_rx_payload_buffer[1];
-        }
-        else if(m_config_local.protocol == UESB_PROTOCOL_ESB)
-        {
-            m_tx_payload_buffer[0] = m_rx_payload_buffer[0];
-            m_tx_payload_buffer[1] = 0;
-
-            m_uesb_mainstate = UESB_STATE_PRX_SEND_ACK;
-        }
-
-        NRF_RADIO->TXADDRESS = NRF_RADIO->RXMATCH;
-        NRF_RADIO->PACKETPTR = (uint32_t)m_tx_payload_buffer;
-
-        on_radio_disabled = on_radio_disabled_esb_dpl_rx_ack;
-    }
-    else
-    {
-        NRF_RADIO->SHORTS = RADIO_SHORTS_COMMON;
-        update_rf_payload_format(m_config_local.payload_length);
-        NRF_RADIO->PACKETPTR = (uint32_t)m_rx_payload_buffer;
-        NRF_RADIO->EVENTS_DISABLED = 0;
-        NRF_RADIO->TASKS_DISABLE = 1;
-        while(NRF_RADIO->EVENTS_DISABLED == 0);
-        NRF_RADIO->EVENTS_DISABLED = 0;
-        NRF_RADIO->SHORTS = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_TXEN_Msk;
-        NRF_RADIO->TASKS_RXEN = 1;
-    }
-    if(set_rx_interrupt)
-    {
-        rx_fifo_push_rfbuf(NRF_RADIO->RXMATCH);
-        m_interrupt_flags |= UESB_INT_RX_DR_MSK;
-        if(m_event_handler != 0) m_event_handler();
-    }
-}
-
-static void on_radio_disabled_esb_dpl_rx_ack(void)
-{
-    NRF_RADIO->SHORTS = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_TXEN_Msk;
-    update_rf_payload_format(m_config_local.payload_length);
-    NRF_RADIO->PACKETPTR = (uint32_t)m_rx_payload_buffer;
-    on_radio_disabled = on_radio_disabled_esb_dpl_rx;
-
-    if(m_uesb_mainstate == UESB_STATE_PRX_SEND_ACK)
-    {
-        // In the case of UESB_STATE_PRX_SEND_ACK_PAYLOAD the state will be updated when the next packet is received.
-        m_uesb_mainstate = UESB_STATE_PRX;
-    }
-}
-
-static void on_radio_end_sb_tx(void)
-{
-    m_interrupt_flags |= UESB_INT_TX_SUCCESS_MSK;
-    tx_fifo_remove_last();
-    if(m_config_local.tx_mode == UESB_TXMODE_MANUAL || m_tx_fifo.count == 0)
-    {
-        // No more packets to send. Disable the radio and set the state to idle.
-        NRF_RADIO->EVENTS_DISABLED = 0;
-        NRF_RADIO->TASKS_DISABLE = 1;
-        while(!NRF_RADIO->EVENTS_DISABLED);
-        NRF_RADIO->EVENTS_DISABLED = 0;
-        m_uesb_mainstate = UESB_STATE_IDLE;
-        if(m_event_handler != 0) m_event_handler();
-    }
-    else
-    {
-        // Send another packet automatically without disabling the radio first.
-        current_payload = m_tx_fifo.payload_ptr[m_tx_fifo.exit_point];
-
-        update_rf_payload_format(current_payload->length);
-        memcpy(&m_tx_payload_buffer[0], current_payload->data, current_payload->length);
-
-        NRF_RADIO->TXADDRESS = current_payload->pipe;
-
-        NVIC_ClearPendingIRQ(RADIO_IRQn);
-        NVIC_EnableIRQ(RADIO_IRQn);
-
-        NRF_RADIO->EVENTS_ADDRESS = NRF_RADIO->EVENTS_PAYLOAD = 0;
-        NRF_RADIO->TASKS_START = 1;
-
-    }
-}
-
-static void on_radio_end_sb_rx(void)
-{
-    if(NRF_RADIO->CRCSTATUS != 0 && rx_fifo_push_rfbuf(NRF_RADIO->RXMATCH))
-    {
-        m_interrupt_flags |= UESB_INT_RX_DR_MSK;
-        if(m_event_handler != 0) m_event_handler();
-    }
-}
diff -r a01a54c0dc90 -r 66f95e364222 micro_esb.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/micro_esb.cpp	Thu Feb 04 10:36:44 2021 +0000
@@ -0,0 +1,876 @@
+/* Copyright (c) 2014 Nordic Semiconductor. All Rights Reserved.
+ *
+ * The information contained herein is property of Nordic Semiconductor ASA.
+ * Terms and conditions of usage are described in detail in NORDIC
+ * SEMICONDUCTOR STANDARD SOFTWARE LICENSE AGREEMENT.
+ *
+ * Licensees are granted free, non-transferable use of the information. NO
+ * WARRANTY of ANY KIND is provided. This heading must NOT be removed from
+ * the file.
+ *
+ */
+
+#include "micro_esb.h"
+#include "uesb_error_codes.h"
+//#include "nrf_gpio.h"
+#include <string.h>
+
+
+static uesb_event_handler_t     m_event_handler;
+
+// RF parameters
+static uesb_config_t            m_config_local;
+
+// TX FIFO
+static uesb_payload_t           m_tx_fifo_payload[UESB_CORE_TX_FIFO_SIZE];
+static uesb_payload_tx_fifo_t   m_tx_fifo;
+
+// RX FIFO
+static uesb_payload_t           m_rx_fifo_payload[UESB_CORE_RX_FIFO_SIZE];
+static uesb_payload_rx_fifo_t   m_rx_fifo;
+
+static  uint8_t                 m_tx_payload_buffer[UESB_CORE_MAX_PAYLOAD_LENGTH + 2];
+static  uint8_t                 m_rx_payload_buffer[UESB_CORE_MAX_PAYLOAD_LENGTH + 2];
+
+// Run time variables
+static volatile uint32_t        m_interrupt_flags       = 0;
+static uint32_t                 m_pid                   = 0;
+static volatile uint32_t        m_retransmits_remaining;
+static volatile uint32_t        m_last_tx_attempts;
+static volatile uint8_t         m_last_rx_packet_pid = 0xFF;
+static volatile uint32_t        m_last_rx_packet_crc = 0xFFFFFFFF;
+static volatile uint32_t        m_wait_for_ack_timeout_us;
+
+static uesb_payload_t           *current_payload;
+
+static uesb_mainstate_t         m_uesb_mainstate        = UESB_STATE_UNINITIALIZED;
+
+// Constant parameters
+#define                         RX_WAIT_FOR_ACK_TIMEOUT_US_2MBPS   48   // Smallest reliable value - 43
+#define                         RX_WAIT_FOR_ACK_TIMEOUT_US_1MBPS   64   // Smallest reliable value - 59
+#define                         RX_WAIT_FOR_ACK_TIMEOUT_US_250KBPS 250
+
+// Macros
+#define                         DISABLE_RF_IRQ      NVIC_DisableIRQ(RADIO_IRQn)
+#define                         ENABLE_RF_IRQ       NVIC_EnableIRQ(RADIO_IRQn)
+
+#define                         RADIO_SHORTS_COMMON ( RADIO_SHORTS_READY_START_Msk | RADIO_SHORTS_END_DISABLE_Msk | \
+                                                      RADIO_SHORTS_ADDRESS_RSSISTART_Msk | RADIO_SHORTS_DISABLED_RSSISTOP_Msk )
+
+// These function pointers are changed dynamically, depending on protocol configuration and state
+static void (*on_radio_disabled)(void) = 0;
+static void (*on_radio_end)(void) = 0;
+static void (*update_rf_payload_format)(uint32_t payload_length) = 0;
+
+// The following functions are assigned to the function pointers above
+static void on_radio_disabled_esb_dpl_tx_noack(void);
+static void on_radio_disabled_esb_dpl_tx(void);
+static void on_radio_disabled_esb_dpl_tx_wait_for_ack(void);
+static void on_radio_disabled_esb_dpl_rx(void);
+static void on_radio_disabled_esb_dpl_rx_ack(void);
+
+static void on_radio_end_sb_tx(void);
+static void on_radio_end_sb_rx(void);
+
+static void update_rf_payload_format_esb_dpl(uint32_t payload_length)
+{
+#if(UESB_CORE_MAX_PAYLOAD_LENGTH <= 32)
+    NRF_RADIO->PCNF0 = (0 << RADIO_PCNF0_S0LEN_Pos) | (6 << RADIO_PCNF0_LFLEN_Pos) | (3 << RADIO_PCNF0_S1LEN_Pos);
+#else
+    NRF_RADIO->PCNF0 = (0 << RADIO_PCNF0_S0LEN_Pos) | (8 << RADIO_PCNF0_LFLEN_Pos) | (3 << RADIO_PCNF0_S1LEN_Pos);
+#endif
+    NRF_RADIO->PCNF1 = (RADIO_PCNF1_WHITEEN_Disabled        << RADIO_PCNF1_WHITEEN_Pos) |
+                       (RADIO_PCNF1_ENDIAN_Big              << RADIO_PCNF1_ENDIAN_Pos)  |
+                       ((m_config_local.rf_addr_length - 1) << RADIO_PCNF1_BALEN_Pos)   |
+                       (0                                   << RADIO_PCNF1_STATLEN_Pos) |
+                       (UESB_CORE_MAX_PAYLOAD_LENGTH        << RADIO_PCNF1_MAXLEN_Pos);
+}
+
+static void update_rf_payload_format_esb(uint32_t payload_length)
+{
+    NRF_RADIO->PCNF0 = (1 << RADIO_PCNF0_S0LEN_Pos) | (0 << RADIO_PCNF0_LFLEN_Pos) | (1 << RADIO_PCNF0_S1LEN_Pos);
+    NRF_RADIO->PCNF1 = (RADIO_PCNF1_WHITEEN_Disabled        << RADIO_PCNF1_WHITEEN_Pos) |
+                       (RADIO_PCNF1_ENDIAN_Big              << RADIO_PCNF1_ENDIAN_Pos)  |
+                       ((m_config_local.rf_addr_length - 1) << RADIO_PCNF1_BALEN_Pos)   |
+                       (payload_length                      << RADIO_PCNF1_STATLEN_Pos) |
+                       (payload_length                      << RADIO_PCNF1_MAXLEN_Pos);
+}
+
+static void update_rf_payload_format_sb(uint32_t payload_length)
+{
+    NRF_RADIO->PCNF0 = (0 << RADIO_PCNF0_S0LEN_Pos) | (0 << RADIO_PCNF0_LFLEN_Pos) | (0 << RADIO_PCNF0_S1LEN_Pos);
+    NRF_RADIO->PCNF1 = (RADIO_PCNF1_WHITEEN_Disabled        << RADIO_PCNF1_WHITEEN_Pos) |
+                       (RADIO_PCNF1_ENDIAN_Big              << RADIO_PCNF1_ENDIAN_Pos)  |
+                       ((m_config_local.rf_addr_length - 1) << RADIO_PCNF1_BALEN_Pos)   |
+                       (payload_length                      << RADIO_PCNF1_STATLEN_Pos) |
+                       (payload_length                      << RADIO_PCNF1_MAXLEN_Pos);
+}
+
+// Function that swaps the bits within each byte in a uint32. Used to convert from nRF24L type addressing to nRF51 type addressing
+static uint32_t bytewise_bit_swap(uint32_t inp)
+{
+    inp = (inp & 0xF0F0F0F0) >> 4 | (inp & 0x0F0F0F0F) << 4;
+    inp = (inp & 0xCCCCCCCC) >> 2 | (inp & 0x33333333) << 2;
+    return (inp & 0xAAAAAAAA) >> 1 | (inp & 0x55555555) << 1;
+}
+
+static void update_radio_parameters()
+{
+    // Protocol
+    switch(m_config_local.protocol)
+    {
+        case UESB_PROTOCOL_ESB_DPL:
+            update_rf_payload_format = update_rf_payload_format_esb_dpl;
+            break;
+        case UESB_PROTOCOL_ESB:
+            update_rf_payload_format = update_rf_payload_format_esb;
+            break;
+        case UESB_PROTOCOL_SB:
+            update_rf_payload_format = update_rf_payload_format_sb;
+            on_radio_end = (m_config_local.mode == UESB_MODE_PTX ? on_radio_end_sb_tx : on_radio_end_sb_rx);
+            break;
+    }
+    // TX power
+    NRF_RADIO->TXPOWER   = m_config_local.tx_output_power   << RADIO_TXPOWER_TXPOWER_Pos;
+
+    // RF bitrate
+    NRF_RADIO->MODE      = m_config_local.bitrate           << RADIO_MODE_MODE_Pos;
+    switch(m_config_local.bitrate)
+    {
+        case UESB_BITRATE_2MBPS:
+            m_wait_for_ack_timeout_us = RX_WAIT_FOR_ACK_TIMEOUT_US_2MBPS;
+            break;
+        case UESB_BITRATE_1MBPS:
+            m_wait_for_ack_timeout_us = RX_WAIT_FOR_ACK_TIMEOUT_US_1MBPS;
+            break;
+        case UESB_BITRATE_250KBPS:
+            m_wait_for_ack_timeout_us = RX_WAIT_FOR_ACK_TIMEOUT_US_250KBPS;
+            break;
+    }
+
+    // CRC configuration
+    NRF_RADIO->CRCCNF    = m_config_local.crc               << RADIO_CRCCNF_LEN_Pos;
+    if(m_config_local.crc == RADIO_CRCCNF_LEN_Two)
+    {
+        NRF_RADIO->CRCINIT = 0xFFFFUL;      // Initial value
+        NRF_RADIO->CRCPOLY = 0x11021UL;     // CRC poly: x^16+x^12^x^5+1
+    }
+    else if(m_config_local.crc == RADIO_CRCCNF_LEN_One)
+    {
+        NRF_RADIO->CRCINIT = 0xFFUL;        // Initial value
+        NRF_RADIO->CRCPOLY = 0x107UL;       // CRC poly: x^8+x^2^x^1+1
+    }
+
+    // Packet format
+    update_rf_payload_format(m_config_local.payload_length);
+
+    // Radio address config
+    NRF_RADIO->PREFIX0 = bytewise_bit_swap(m_config_local.rx_address_p3 << 24 | m_config_local.rx_address_p2 << 16 | m_config_local.rx_address_p1[0] << 8 | m_config_local.rx_address_p0[0]);
+    NRF_RADIO->PREFIX1 = bytewise_bit_swap(m_config_local.rx_address_p7 << 24 | m_config_local.rx_address_p6 << 16 | m_config_local.rx_address_p5 << 8 | m_config_local.rx_address_p4);
+    NRF_RADIO->BASE0   = bytewise_bit_swap(m_config_local.rx_address_p0[1] << 24 | m_config_local.rx_address_p0[2] << 16 | m_config_local.rx_address_p0[3] << 8 | m_config_local.rx_address_p0[4]);
+    NRF_RADIO->BASE1   = bytewise_bit_swap(m_config_local.rx_address_p1[1] << 24 | m_config_local.rx_address_p1[2] << 16 | m_config_local.rx_address_p1[3] << 8 | m_config_local.rx_address_p1[4]);
+}
+
+static void initialize_fifos()
+{
+    m_tx_fifo.entry_point = 0;
+    m_tx_fifo.exit_point  = 0;
+    m_tx_fifo.count       = 0;
+    for(int i = 0; i < UESB_CORE_TX_FIFO_SIZE; i++)
+    {
+        m_tx_fifo.payload_ptr[i] = &m_tx_fifo_payload[i];
+    }
+
+    m_rx_fifo.entry_point = 0;
+    m_rx_fifo.exit_point  = 0;
+    m_rx_fifo.count       = 0;
+    for(int i = 0; i < UESB_CORE_RX_FIFO_SIZE; i++)
+    {
+        m_rx_fifo.payload_ptr[i] = &m_rx_fifo_payload[i];
+    }
+}
+
+static void tx_fifo_remove_last()
+{
+    if(m_tx_fifo.count > 0)
+    {
+        DISABLE_RF_IRQ;
+        m_tx_fifo.count--;
+        m_tx_fifo.exit_point++;
+        if(m_tx_fifo.exit_point >= UESB_CORE_TX_FIFO_SIZE) m_tx_fifo.exit_point = 0;
+        ENABLE_RF_IRQ;
+    }
+}
+
+static bool rx_fifo_push_rfbuf(uint8_t pipe)
+{
+    if(m_rx_fifo.count < UESB_CORE_RX_FIFO_SIZE)
+    {
+        if(m_config_local.protocol == UESB_PROTOCOL_ESB_DPL)
+        {
+            if(m_rx_payload_buffer[0] > UESB_CORE_MAX_PAYLOAD_LENGTH) return false;
+            m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->length = m_rx_payload_buffer[0];
+        }
+        else
+        {
+            m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->length = m_config_local.payload_length;
+        }
+        if(m_config_local.protocol == UESB_PROTOCOL_SB)
+        {
+            memcpy(m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->data, &m_rx_payload_buffer[0], m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->length);
+        }
+        else
+        {
+            memcpy(m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->data, &m_rx_payload_buffer[2], m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->length);
+        }
+        m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->pipe = pipe;
+        m_rx_fifo.payload_ptr[m_rx_fifo.entry_point]->rssi = NRF_RADIO->RSSISAMPLE;
+        if(++m_rx_fifo.entry_point >= UESB_CORE_RX_FIFO_SIZE) m_rx_fifo.entry_point = 0;
+        m_rx_fifo.count++;
+        return true;
+    }
+    return false;
+}
+
+static void sys_timer_init()
+{
+    // Configure the system timer with a 1 MHz base frequency
+    UESB_SYS_TIMER->PRESCALER = 4;
+    UESB_SYS_TIMER->BITMODE   = TIMER_BITMODE_BITMODE_16Bit;
+    UESB_SYS_TIMER->SHORTS    = TIMER_SHORTS_COMPARE1_CLEAR_Msk | TIMER_SHORTS_COMPARE1_STOP_Msk;
+}
+
+static void ppi_init()
+{
+    NRF_PPI->CH[UESB_PPI_TIMER_START].EEP = (uint32_t)&NRF_RADIO->EVENTS_READY;
+    NRF_PPI->CH[UESB_PPI_TIMER_START].TEP = (uint32_t)&UESB_SYS_TIMER->TASKS_START;
+    NRF_PPI->CH[UESB_PPI_TIMER_STOP].EEP =  (uint32_t)&NRF_RADIO->EVENTS_ADDRESS;
+    NRF_PPI->CH[UESB_PPI_TIMER_STOP].TEP =  (uint32_t)&UESB_SYS_TIMER->TASKS_STOP;
+    NRF_PPI->CH[UESB_PPI_RX_TIMEOUT].EEP = (uint32_t)&UESB_SYS_TIMER->EVENTS_COMPARE[0];
+    NRF_PPI->CH[UESB_PPI_RX_TIMEOUT].TEP = (uint32_t)&NRF_RADIO->TASKS_DISABLE;
+    NRF_PPI->CH[UESB_PPI_TX_START].EEP = (uint32_t)&UESB_SYS_TIMER->EVENTS_COMPARE[1];
+    NRF_PPI->CH[UESB_PPI_TX_START].TEP = (uint32_t)&NRF_RADIO->TASKS_TXEN;
+}
+
+uint32_t uesb_read_rx_payload(uesb_payload_t *payload)
+{
+    if(m_uesb_mainstate == UESB_STATE_UNINITIALIZED) return UESB_ERROR_NOT_INITIALIZED;
+    if(m_rx_fifo.count == 0) return UESB_ERROR_RX_FIFO_EMPTY;
+
+    DISABLE_RF_IRQ;
+    payload->length = m_rx_fifo.payload_ptr[m_rx_fifo.exit_point]->length;
+    payload->pipe   = m_rx_fifo.payload_ptr[m_rx_fifo.exit_point]->pipe;
+    payload->rssi   = m_rx_fifo.payload_ptr[m_rx_fifo.exit_point]->rssi;
+    memcpy(payload->data, m_rx_fifo.payload_ptr[m_rx_fifo.exit_point]->data, payload->length);
+    if(++m_rx_fifo.exit_point >= UESB_CORE_RX_FIFO_SIZE) m_rx_fifo.exit_point = 0;
+    m_rx_fifo.count--;
+    ENABLE_RF_IRQ;
+
+    return UESB_SUCCESS;
+}
+
+
+uint32_t uesb_init(uesb_config_t *parameters)
+{
+    if(m_uesb_mainstate != UESB_STATE_UNINITIALIZED) return UESB_ERROR_ALREADY_INITIALIZED;
+    m_event_handler = parameters->event_handler;
+    memcpy(&m_config_local, parameters, sizeof(uesb_config_t));
+
+    m_interrupt_flags    = 0;
+    m_pid                = 0;
+    m_last_rx_packet_pid = 0xFF;
+    m_last_rx_packet_crc = 0xFFFFFFFF;
+
+    update_radio_parameters();
+
+    initialize_fifos();
+
+    sys_timer_init();
+
+    ppi_init();
+
+    NVIC_SetPriority(RADIO_IRQn, m_config_local.radio_irq_priority & 0x03);
+
+    //m_uesb_initialized = true;
+    m_uesb_mainstate = UESB_STATE_IDLE;
+
+    return UESB_SUCCESS;
+}
+
+uint32_t uesb_disable(void)
+{
+    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
+    NRF_PPI->CHENCLR = (1 << UESB_PPI_TIMER_START) | (1 << UESB_PPI_TIMER_STOP) | (1 << UESB_PPI_RX_TIMEOUT) | (1 << UESB_PPI_TX_START);
+    m_uesb_mainstate = UESB_STATE_UNINITIALIZED;
+    return UESB_SUCCESS;
+}
+
+static void start_tx_transaction()
+{
+    bool ack;
+    m_last_tx_attempts = 1;
+    // Prepare the payload
+    current_payload = m_tx_fifo.payload_ptr[m_tx_fifo.exit_point];
+    m_pid = (m_pid + 1) % 4;
+    switch(m_config_local.protocol)
+    {
+        case UESB_PROTOCOL_SB:
+            update_rf_payload_format(current_payload->length);
+            memcpy(&m_tx_payload_buffer[0], current_payload->data, current_payload->length);
+            NRF_RADIO->SHORTS   = RADIO_SHORTS_READY_START_Msk;
+            NRF_RADIO->INTENSET = RADIO_INTENSET_END_Msk;
+            on_radio_disabled   = on_radio_disabled_esb_dpl_tx_noack;
+            m_uesb_mainstate    = UESB_STATE_PTX_TX;
+            break;
+
+        case UESB_PROTOCOL_ESB:
+            update_rf_payload_format(current_payload->length);
+            m_tx_payload_buffer[0] = 0xCC | m_pid;
+            m_tx_payload_buffer[1] = 0;
+            memcpy(&m_tx_payload_buffer[2], current_payload->data, current_payload->length);
+
+            NRF_RADIO->SHORTS   = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_RXEN_Msk;
+            NRF_RADIO->INTENSET = RADIO_INTENSET_DISABLED_Msk | RADIO_INTENSET_READY_Msk;
+
+            // Configure the retransmit counter
+            m_retransmits_remaining = m_config_local.retransmit_count;
+            on_radio_disabled = on_radio_disabled_esb_dpl_tx;
+            m_uesb_mainstate = UESB_STATE_PTX_TX_ACK;
+            break;
+
+        case UESB_PROTOCOL_ESB_DPL:
+            ack = current_payload->noack == 0 || m_config_local.dynamic_ack_enabled == 0;
+            m_tx_payload_buffer[0] = current_payload->length;
+            m_tx_payload_buffer[1] = m_pid << 1 | ((current_payload->noack == 0 && m_config_local.dynamic_ack_enabled) ? 0x01 : 0x00);
+            memcpy(&m_tx_payload_buffer[2], current_payload->data, current_payload->length);
+            if(ack)
+            {
+                NRF_RADIO->SHORTS   = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_RXEN_Msk;
+                NRF_RADIO->INTENSET = RADIO_INTENSET_DISABLED_Msk | RADIO_INTENSET_READY_Msk;
+
+                // Configure the retransmit counter
+                m_retransmits_remaining = m_config_local.retransmit_count;
+                on_radio_disabled = on_radio_disabled_esb_dpl_tx;
+                m_uesb_mainstate = UESB_STATE_PTX_TX_ACK;
+            }
+            else
+            {
+                NRF_RADIO->SHORTS   = RADIO_SHORTS_COMMON;
+                NRF_RADIO->INTENSET = RADIO_INTENSET_DISABLED_Msk;
+                on_radio_disabled   = on_radio_disabled_esb_dpl_tx_noack;
+                m_uesb_mainstate    = UESB_STATE_PTX_TX;
+            }
+            break;
+    }
+
+    NRF_RADIO->TXADDRESS = current_payload->pipe;
+    NRF_RADIO->RXADDRESSES = 1 << current_payload->pipe;
+
+    NRF_RADIO->FREQUENCY = m_config_local.rf_channel;
+
+    NRF_RADIO->PACKETPTR = (uint32_t)m_tx_payload_buffer;
+
+    NVIC_ClearPendingIRQ(RADIO_IRQn);
+    NVIC_EnableIRQ(RADIO_IRQn);
+
+    NRF_RADIO->EVENTS_ADDRESS = NRF_RADIO->EVENTS_PAYLOAD = NRF_RADIO->EVENTS_DISABLED = 0;
+    DEBUG_PIN_SET(DEBUGPIN4);
+    NRF_RADIO->TASKS_TXEN  = 1;
+}
+
+static uint32_t write_tx_payload(uesb_payload_t *payload, bool noack) // ~50us @ 61 bytes SB
+{
+    if(m_uesb_mainstate == UESB_STATE_UNINITIALIZED) return UESB_ERROR_NOT_INITIALIZED;
+    if(m_tx_fifo.count >= UESB_CORE_TX_FIFO_SIZE) return UESB_ERROR_TX_FIFO_FULL;
+
+    DISABLE_RF_IRQ;
+    if(noack && m_config_local.dynamic_ack_enabled) payload->noack = 1;
+    else payload->noack = 0;
+    memcpy(m_tx_fifo.payload_ptr[m_tx_fifo.entry_point], payload, sizeof(uesb_payload_t));
+    m_tx_fifo.entry_point++;
+    if(m_tx_fifo.entry_point >= UESB_CORE_TX_FIFO_SIZE) m_tx_fifo.entry_point = 0;
+    m_tx_fifo.count++;
+    ENABLE_RF_IRQ;
+
+    if(m_config_local.tx_mode == UESB_TXMODE_AUTO && m_uesb_mainstate == UESB_STATE_IDLE)
+    {
+        start_tx_transaction();
+    }
+
+    return UESB_SUCCESS;
+}
+
+uint32_t uesb_write_tx_payload(uesb_payload_t *payload)
+{
+    return write_tx_payload(payload, false);
+}
+
+uint32_t uesb_write_tx_payload_noack(uesb_payload_t *payload)
+{
+    if(m_config_local.dynamic_ack_enabled == 0) return UESB_ERROR_DYN_ACK_NOT_ENABLED;
+    return write_tx_payload(payload, true);
+}
+
+uint32_t uesb_write_ack_payload(uesb_payload_t *payload)
+{
+    if(m_uesb_mainstate == UESB_STATE_UNINITIALIZED) return UESB_ERROR_NOT_INITIALIZED;
+    if((m_uesb_mainstate != UESB_STATE_PRX) &&
+       (m_uesb_mainstate != UESB_STATE_PRX_SEND_ACK) &&
+       (m_uesb_mainstate != UESB_STATE_PRX_SEND_ACK_PAYLOAD))
+    {
+        return UESB_ERROR_NOT_IN_RX_MODE;
+    }
+    if(m_tx_fifo.count >= UESB_CORE_TX_FIFO_SIZE) return UESB_ERROR_TX_FIFO_FULL;
+
+    DISABLE_RF_IRQ;
+    memcpy(m_tx_fifo.payload_ptr[m_tx_fifo.entry_point], payload, sizeof(uesb_payload_t));
+    m_tx_fifo.entry_point++;
+    if(m_tx_fifo.entry_point >= UESB_CORE_TX_FIFO_SIZE) m_tx_fifo.entry_point = 0;
+    m_tx_fifo.count++;
+    ENABLE_RF_IRQ;
+
+    return UESB_SUCCESS;
+}
+
+
+uint32_t uesb_start_tx()
+{
+    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
+    if(m_tx_fifo.count == 0) return UESB_ERROR_TX_FIFO_EMPTY;
+    start_tx_transaction();
+    return UESB_SUCCESS;
+}
+
+uint32_t uesb_start_rx(void)
+{
+    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
+
+    NRF_RADIO->INTENCLR = 0xFFFFFFFF;
+    NRF_RADIO->EVENTS_DISABLED = 0;
+    on_radio_disabled = on_radio_disabled_esb_dpl_rx;
+    switch(m_config_local.protocol)
+    {
+        case UESB_PROTOCOL_SB:
+            NRF_RADIO->SHORTS      = RADIO_SHORTS_READY_START_Msk | RADIO_SHORTS_END_START_Msk;
+            NRF_RADIO->INTENSET    = RADIO_INTENSET_END_Msk;
+            m_uesb_mainstate       = UESB_STATE_PRX;
+            break;
+        case UESB_PROTOCOL_ESB:
+            NRF_RADIO->SHORTS      = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_TXEN_Msk;
+            NRF_RADIO->INTENSET    = RADIO_INTENSET_DISABLED_Msk;
+            m_uesb_mainstate       = UESB_STATE_PRX;
+            break;
+        case UESB_PROTOCOL_ESB_DPL:
+            NRF_RADIO->SHORTS      = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_TXEN_Msk;
+            NRF_RADIO->INTENSET    = RADIO_INTENSET_DISABLED_Msk;
+            m_uesb_mainstate       = UESB_STATE_PRX;
+            break;
+    }
+
+    NRF_RADIO->RXADDRESSES = m_config_local.rx_pipes_enabled;
+
+    NRF_RADIO->FREQUENCY = m_config_local.rf_channel;
+
+    NRF_RADIO->PACKETPTR = (uint32_t)m_rx_payload_buffer;
+
+    NVIC_ClearPendingIRQ(RADIO_IRQn);
+    NVIC_EnableIRQ(RADIO_IRQn);
+
+    NRF_RADIO->EVENTS_ADDRESS = NRF_RADIO->EVENTS_PAYLOAD = NRF_RADIO->EVENTS_DISABLED = 0;
+    NRF_RADIO->TASKS_RXEN  = 1;
+    return UESB_SUCCESS;
+}
+
+uint32_t uesb_stop_rx(void)
+{
+    if((m_uesb_mainstate == UESB_STATE_PRX) || (m_uesb_mainstate == UESB_STATE_PRX_SEND_ACK_PAYLOAD))
+    {
+        NRF_RADIO->SHORTS = 0;
+        NRF_RADIO->INTENCLR = 0xFFFFFFFF;
+        on_radio_disabled = NULL;
+        NRF_RADIO->EVENTS_DISABLED = 0;
+        NRF_RADIO->TASKS_DISABLE = 1;
+        while(NRF_RADIO->EVENTS_DISABLED == 0);
+        m_uesb_mainstate = UESB_STATE_IDLE;
+        return UESB_SUCCESS;
+    }
+    return UESB_ERROR_NOT_IN_RX_MODE;
+}
+
+uint32_t uesb_get_tx_attempts(uint32_t *attempts)
+{
+    if(m_uesb_mainstate == UESB_STATE_UNINITIALIZED) return UESB_ERROR_NOT_INITIALIZED;
+    *attempts = m_last_tx_attempts;
+    return UESB_SUCCESS;
+}
+
+uint32_t uesb_flush_tx(void)
+{
+    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
+    DISABLE_RF_IRQ;
+    m_tx_fifo.count = 0;
+    m_tx_fifo.entry_point = m_tx_fifo.exit_point = 0;
+    ENABLE_RF_IRQ;
+    return UESB_SUCCESS;
+}
+
+uint32_t uesb_flush_rx(void)
+{
+    DISABLE_RF_IRQ;
+    m_rx_fifo.count = 0;
+    m_rx_fifo.entry_point = 0;
+    ENABLE_RF_IRQ;
+    return UESB_SUCCESS;
+}
+
+uint32_t uesb_get_clear_interrupts(uint32_t *interrupts)
+{
+    DISABLE_RF_IRQ;
+    *interrupts = m_interrupt_flags;
+    m_interrupt_flags = 0;
+    ENABLE_RF_IRQ;
+    return UESB_SUCCESS;
+}
+
+uint32_t uesb_set_address(uesb_address_type_t address, const uint8_t *data_ptr)
+{
+    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
+    switch(address)
+    {
+        case UESB_ADDRESS_PIPE0:
+            memcpy(m_config_local.rx_address_p0, data_ptr, m_config_local.rf_addr_length);
+            break;
+        case UESB_ADDRESS_PIPE1:
+            memcpy(m_config_local.rx_address_p1, data_ptr, m_config_local.rf_addr_length);
+            break;
+        case UESB_ADDRESS_PIPE2:
+            m_config_local.rx_address_p2 = *data_ptr;
+            break;
+        case UESB_ADDRESS_PIPE3:
+            m_config_local.rx_address_p3 = *data_ptr;
+            break;
+        case UESB_ADDRESS_PIPE4:
+            m_config_local.rx_address_p4 = *data_ptr;
+            break;
+        case UESB_ADDRESS_PIPE5:
+            m_config_local.rx_address_p5 = *data_ptr;
+            break;
+        case UESB_ADDRESS_PIPE6:
+            m_config_local.rx_address_p6 = *data_ptr;
+            break;
+        case UESB_ADDRESS_PIPE7:
+            m_config_local.rx_address_p7 = *data_ptr;
+            break;
+        default:
+            return UESB_ERROR_INVALID_PARAMETERS;
+    }
+    update_radio_parameters();
+    return UESB_SUCCESS;
+}
+
+uint32_t uesb_set_rf_channel(uint32_t channel)
+{
+    if(channel > 125) return UESB_ERROR_INVALID_PARAMETERS;
+    m_config_local.rf_channel = channel;
+    return UESB_SUCCESS;
+}
+
+uint32_t uesb_set_tx_power(uesb_tx_power_t tx_output_power)
+{
+    if(m_uesb_mainstate != UESB_STATE_IDLE) return UESB_ERROR_NOT_IDLE;
+    if ( m_config_local.tx_output_power == tx_output_power ) return UESB_SUCCESS;
+    m_config_local.tx_output_power = tx_output_power;
+    update_radio_parameters();
+    return UESB_SUCCESS;
+}
+
+/*
+
+void RADIO_IRQHandler()
+{
+    if(NRF_RADIO->EVENTS_READY && (NRF_RADIO->INTENSET & RADIO_INTENSET_READY_Msk))
+    {
+        NRF_RADIO->EVENTS_READY = 0;
+
+        DEBUG_PIN_SET(DEBUGPIN1);
+    }
+
+    if(NRF_RADIO->EVENTS_END && (NRF_RADIO->INTENSET & RADIO_INTENSET_END_Msk))
+    {
+        NRF_RADIO->EVENTS_END = 0;
+
+        DEBUG_PIN_SET(DEBUGPIN2);
+
+        // Call the correct on_radio_end function, depending on the current protocol state
+        if(on_radio_end)
+        {
+            on_radio_end();
+        }
+    }
+
+    if(NRF_RADIO->EVENTS_DISABLED && (NRF_RADIO->INTENSET & RADIO_INTENSET_DISABLED_Msk))
+    {
+        NRF_RADIO->EVENTS_DISABLED = 0;
+
+        DEBUG_PIN_SET(DEBUGPIN3);
+
+        // Call the correct on_radio_disable function, depending on the current protocol state
+        if(on_radio_disabled)
+        {
+            on_radio_disabled();
+        }
+    }
+
+    DEBUG_PIN_CLR(DEBUGPIN1);
+    DEBUG_PIN_CLR(DEBUGPIN2);
+    DEBUG_PIN_CLR(DEBUGPIN3);
+    DEBUG_PIN_CLR(DEBUGPIN4);
+} */
+
+static void on_radio_disabled_esb_dpl_tx_noack()
+{
+    m_interrupt_flags |= UESB_INT_TX_SUCCESS_MSK;
+    tx_fifo_remove_last();
+
+    if(m_tx_fifo.count == 0)
+    {
+        m_uesb_mainstate = UESB_STATE_IDLE;
+	if(m_event_handler != 0) m_event_handler();
+    }
+    else
+    {
+        if(m_event_handler != 0) m_event_handler();
+        start_tx_transaction();
+    }
+}
+
+static void on_radio_disabled_esb_dpl_tx()
+{
+    // Remove the DISABLED -> RXEN shortcut, to make sure the radio stays disabled after the RX window
+    NRF_RADIO->SHORTS           = RADIO_SHORTS_COMMON;
+
+    // Make sure the timer is started the next time the radio is ready,
+    // and that it will disable the radio automatically if no packet is received by the time defined in m_wait_for_ack_timeout_us
+    UESB_SYS_TIMER->CC[0]       = m_wait_for_ack_timeout_us;
+    UESB_SYS_TIMER->CC[1]       = m_config_local.retransmit_delay - 130;
+    UESB_SYS_TIMER->TASKS_CLEAR = 1;
+    UESB_SYS_TIMER->EVENTS_COMPARE[0] = 0;
+    UESB_SYS_TIMER->EVENTS_COMPARE[1] = 0;
+    NRF_PPI->CHENSET            = (1 << UESB_PPI_TIMER_START) | (1 << UESB_PPI_RX_TIMEOUT) | (1 << UESB_PPI_TIMER_STOP);
+    NRF_PPI->CHENCLR            = (1 << UESB_PPI_TX_START);
+    NRF_RADIO->EVENTS_END       = 0;
+    if(m_config_local.protocol == UESB_PROTOCOL_ESB)
+    {
+        update_rf_payload_format(0);
+    }
+    NRF_RADIO->PACKETPTR        = (uint32_t)m_rx_payload_buffer;
+    on_radio_disabled           = on_radio_disabled_esb_dpl_tx_wait_for_ack;
+    m_uesb_mainstate            = UESB_STATE_PTX_RX_ACK;
+}
+
+static void on_radio_disabled_esb_dpl_tx_wait_for_ack()
+{
+    // This marks the completion of a TX_RX sequence (TX with ACK)
+
+    // Make sure the timer will not deactivate the radio if a packet is received
+    NRF_PPI->CHENCLR = (1 << UESB_PPI_TIMER_START) | (1 << UESB_PPI_RX_TIMEOUT) | (1 << UESB_PPI_TIMER_STOP);
+
+    // If the radio has received a packet and the CRC status is OK
+    if(NRF_RADIO->EVENTS_END && NRF_RADIO->CRCSTATUS != 0)
+    {
+        UESB_SYS_TIMER->TASKS_STOP = 1;
+        NRF_PPI->CHENCLR = (1 << UESB_PPI_TX_START);
+        m_interrupt_flags |= UESB_INT_TX_SUCCESS_MSK;
+        m_last_tx_attempts = m_config_local.retransmit_count - m_retransmits_remaining + 1;
+        tx_fifo_remove_last();
+        if(m_rx_payload_buffer[0] > 0)
+        {
+            if(rx_fifo_push_rfbuf((uint8_t)NRF_RADIO->TXADDRESS))
+            {
+                m_interrupt_flags |= UESB_INT_RX_DR_MSK;
+            }
+        }
+
+        if((m_tx_fifo.count == 0) || (m_config_local.tx_mode == UESB_TXMODE_MANUAL))
+	{
+            m_uesb_mainstate = UESB_STATE_IDLE;
+	    if(m_event_handler != 0) m_event_handler();
+        }
+        else
+	{
+            if(m_event_handler != 0) m_event_handler();
+            start_tx_transaction();
+	}
+    }
+    else
+    {
+        if(m_retransmits_remaining-- == 0)
+        {
+            UESB_SYS_TIMER->TASKS_STOP = 1;
+            NRF_PPI->CHENCLR = (1 << UESB_PPI_TX_START);
+            // All retransmits are expended, and the TX operation is suspended
+            m_last_tx_attempts = m_config_local.retransmit_count + 1;
+            m_interrupt_flags |= UESB_INT_TX_FAILED_MSK;
+
+            m_uesb_mainstate = UESB_STATE_IDLE;
+	    if(m_event_handler != 0) m_event_handler();
+        }
+        else
+        {
+            // We still have more retransmits left, and we should enter TX mode again as soon as the system timer reaches CC[1]
+            NRF_RADIO->SHORTS = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_RXEN_Msk;
+            update_rf_payload_format(current_payload->length);
+            NRF_RADIO->PACKETPTR = (uint32_t)m_tx_payload_buffer;
+            on_radio_disabled = on_radio_disabled_esb_dpl_tx;
+            m_uesb_mainstate = UESB_STATE_PTX_TX_ACK;
+            UESB_SYS_TIMER->TASKS_START = 1;
+            NRF_PPI->CHENSET = (1 << UESB_PPI_TX_START);
+            if(UESB_SYS_TIMER->EVENTS_COMPARE[1])
+            {
+                NRF_RADIO->TASKS_TXEN = 1;
+            }                 
+        }
+    }
+}
+
+static void on_radio_disabled_esb_dpl_rx(void)
+{
+    bool send_ack = false;
+    bool set_rx_interrupt = false;
+    if(NRF_RADIO->CRCSTATUS != 0 && m_rx_fifo.count < UESB_CORE_RX_FIFO_SIZE)
+    {
+        send_ack = true;
+    }
+    if(send_ack)
+    {
+        NRF_RADIO->SHORTS = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_RXEN_Msk;
+
+        // For a packet to be considered new (and not a retransmit) the PID or the CRC has to be different
+        if(NRF_RADIO->RXCRC != m_last_rx_packet_crc || (m_rx_payload_buffer[1] >> 1) != m_last_rx_packet_pid)
+        {
+	    if((m_uesb_mainstate == UESB_STATE_PRX_SEND_ACK_PAYLOAD) && (m_tx_fifo.count > 0))
+            {
+                // It is assumed that the last ACK payload was recieved.
+                if(++m_tx_fifo.exit_point >= UESB_CORE_RX_FIFO_SIZE) m_tx_fifo.exit_point = 0;
+                m_tx_fifo.count--;
+
+                // ACK payloads also require TX_DS (page 40 of the 'nRF24LE1_Product_Specification_rev1_6.pdf').
+                m_interrupt_flags |= UESB_INT_TX_SUCCESS_MSK;
+            }
+
+            set_rx_interrupt = true;
+            m_last_rx_packet_pid = m_rx_payload_buffer[1] >> 1;
+            m_last_rx_packet_crc = NRF_RADIO->RXCRC;
+        }
+
+        if(m_config_local.protocol == UESB_PROTOCOL_ESB_DPL)
+        {
+	    if(m_tx_fifo.count > 0)
+	    {
+                current_payload = m_tx_fifo.payload_ptr[m_tx_fifo.exit_point];
+
+                update_rf_payload_format(current_payload->length);
+                m_tx_payload_buffer[0] = current_payload->length;
+                memcpy(&m_tx_payload_buffer[2], current_payload->data, current_payload->length);
+
+		m_uesb_mainstate = UESB_STATE_PRX_SEND_ACK_PAYLOAD;
+	    }
+            else
+	    {
+                update_rf_payload_format(0);
+                m_tx_payload_buffer[0] = 0;
+
+                m_uesb_mainstate = UESB_STATE_PRX_SEND_ACK;
+            }
+
+            m_tx_payload_buffer[1] = m_rx_payload_buffer[1];
+        }
+        else if(m_config_local.protocol == UESB_PROTOCOL_ESB)
+        {
+            m_tx_payload_buffer[0] = m_rx_payload_buffer[0];
+            m_tx_payload_buffer[1] = 0;
+
+            m_uesb_mainstate = UESB_STATE_PRX_SEND_ACK;
+        }
+
+        NRF_RADIO->TXADDRESS = NRF_RADIO->RXMATCH;
+        NRF_RADIO->PACKETPTR = (uint32_t)m_tx_payload_buffer;
+
+        on_radio_disabled = on_radio_disabled_esb_dpl_rx_ack;
+    }
+    else
+    {
+        NRF_RADIO->SHORTS = RADIO_SHORTS_COMMON;
+        update_rf_payload_format(m_config_local.payload_length);
+        NRF_RADIO->PACKETPTR = (uint32_t)m_rx_payload_buffer;
+        NRF_RADIO->EVENTS_DISABLED = 0;
+        NRF_RADIO->TASKS_DISABLE = 1;
+        while(NRF_RADIO->EVENTS_DISABLED == 0);
+        NRF_RADIO->EVENTS_DISABLED = 0;
+        NRF_RADIO->SHORTS = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_TXEN_Msk;
+        NRF_RADIO->TASKS_RXEN = 1;
+    }
+    if(set_rx_interrupt)
+    {
+        rx_fifo_push_rfbuf(NRF_RADIO->RXMATCH);
+        m_interrupt_flags |= UESB_INT_RX_DR_MSK;
+        if(m_event_handler != 0) m_event_handler();
+    }
+}
+
+static void on_radio_disabled_esb_dpl_rx_ack(void)
+{
+    NRF_RADIO->SHORTS = RADIO_SHORTS_COMMON | RADIO_SHORTS_DISABLED_TXEN_Msk;
+    update_rf_payload_format(m_config_local.payload_length);
+    NRF_RADIO->PACKETPTR = (uint32_t)m_rx_payload_buffer;
+    on_radio_disabled = on_radio_disabled_esb_dpl_rx;
+
+    if(m_uesb_mainstate == UESB_STATE_PRX_SEND_ACK)
+    {
+        // In the case of UESB_STATE_PRX_SEND_ACK_PAYLOAD the state will be updated when the next packet is received.
+        m_uesb_mainstate = UESB_STATE_PRX;
+    }
+}
+
+static void on_radio_end_sb_tx(void)
+{
+    m_interrupt_flags |= UESB_INT_TX_SUCCESS_MSK;
+    tx_fifo_remove_last();
+    if(m_config_local.tx_mode == UESB_TXMODE_MANUAL || m_tx_fifo.count == 0)
+    {
+        // No more packets to send. Disable the radio and set the state to idle.
+        NRF_RADIO->EVENTS_DISABLED = 0;
+        NRF_RADIO->TASKS_DISABLE = 1;
+        while(!NRF_RADIO->EVENTS_DISABLED);
+        NRF_RADIO->EVENTS_DISABLED = 0;
+        m_uesb_mainstate = UESB_STATE_IDLE;
+        if(m_event_handler != 0) m_event_handler();
+    }
+    else
+    {
+        // Send another packet automatically without disabling the radio first.
+        current_payload = m_tx_fifo.payload_ptr[m_tx_fifo.exit_point];
+
+        update_rf_payload_format(current_payload->length);
+        memcpy(&m_tx_payload_buffer[0], current_payload->data, current_payload->length);
+
+        NRF_RADIO->TXADDRESS = current_payload->pipe;
+
+        NVIC_ClearPendingIRQ(RADIO_IRQn);
+        NVIC_EnableIRQ(RADIO_IRQn);
+
+        NRF_RADIO->EVENTS_ADDRESS = NRF_RADIO->EVENTS_PAYLOAD = 0;
+        NRF_RADIO->TASKS_START = 1;
+
+    }
+}
+
+static void on_radio_end_sb_rx(void)
+{
+    if(NRF_RADIO->CRCSTATUS != 0 && rx_fifo_push_rfbuf(NRF_RADIO->RXMATCH))
+    {
+        m_interrupt_flags |= UESB_INT_RX_DR_MSK;
+        if(m_event_handler != 0) m_event_handler();
+    }
+}
+
diff -r a01a54c0dc90 -r 66f95e364222 micro_esb.h
--- a/micro_esb.h	Mon Mar 23 04:09:41 2015 +0000
+++ b/micro_esb.h	Thu Feb 04 10:36:44 2021 +0000
@@ -16,8 +16,9 @@
 #include <stdbool.h>
 #include <stdint.h>
 //#include "nrf.h"
-#include "nrf51.h"
-#include "nrf51_bitfields.h"
+//#include "nrf51.h"
+//#include "nrf51_bitfields.h"
+#include "nrf_esb.h"
 
 #define DEBUGPIN1   12
 #define DEBUGPIN2   13
@@ -62,11 +63,17 @@
     UESB_MODE_PRX           // Primary receiver (CURRENTLY NOT IMPLEMENTED)
 } uesb_mode_t;
 
-typedef enum {
+/* typedef enum {
     UESB_BITRATE_2MBPS = RADIO_MODE_MODE_Nrf_2Mbit,
     UESB_BITRATE_1MBPS = RADIO_MODE_MODE_Nrf_1Mbit,
     UESB_BITRATE_250KBPS = RADIO_MODE_MODE_Nrf_250Kbit
-} uesb_bitrate_t;
+} uesb_bitrate_t; */
+
+typedef enum {
+    UESB_BITRATE_2MBPS = NRF_ESB_BITRATE_1MBPS,
+    UESB_BITRATE_1MBPS = NRF_ESB_BITRATE_2MBPS,
+    UESB_BITRATE_250KBPS = NRF_ESB_BITRATE_250KBPS
+} uesb_bitrate_t; 
 
 typedef enum {
     UESB_CRC_16BIT = RADIO_CRCCNF_LEN_Two,
diff -r a01a54c0dc90 -r 66f95e364222 nrf_esb.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nrf_esb.c	Thu Feb 04 10:36:44 2021 +0000
@@ -0,0 +1,1604 @@
+/**
+ * Copyright (c) 2016 - 2018, Nordic Semiconductor ASA
+ * 
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form, except as embedded into a Nordic
+ *    Semiconductor ASA integrated circuit in a product or a software update for
+ *    such product, must reproduce the above copyright notice, this list of
+ *    conditions and the following disclaimer in the documentation and/or other
+ *    materials provided with the distribution.
+ * 
+ * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
+ *    contributors may be used to endorse or promote products derived from this
+ *    software without specific prior written permission.
+ * 
+ * 4. This software, with or without modification, must only be used with a
+ *    Nordic Semiconductor ASA integrated circuit.
+ * 
+ * 5. Any software provided in binary form under this license must not be reverse
+ *    engineered, decompiled, modified and/or disassembled.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
+ * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
+ * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ */
+
+#include "nrf_error.h"
+#include "nrf_esb.h"
+#include "nrf_esb_error_codes.h"
+#include "nrf_gpio.h"
+#include <string.h>
+#include <stddef.h>
+#include "sdk_common.h"
+#include "sdk_macros.h"
+#include "app_util.h"
+#include "nrf_log.h"
+#include "nrf_delay.h"
+
+#define BIT_MASK_UINT_8(x) (0xFF >> (8 - (x)))
+#define NRF_ESB_PIPE_COUNT 8
+
+// Constant parameters
+#define RX_WAIT_FOR_ACK_TIMEOUT_US_2MBPS        (48)        /**< 2 Mb RX wait for acknowledgment time-out value. Smallest reliable value - 43. */
+#define RX_WAIT_FOR_ACK_TIMEOUT_US_1MBPS        (64)        /**< 1 Mb RX wait for acknowledgment time-out value. Smallest reliable value - 59. */
+#define RX_WAIT_FOR_ACK_TIMEOUT_US_250KBPS      (250)       /**< 250 Kb RX wait for acknowledgment time-out value. */
+#define RX_WAIT_FOR_ACK_TIMEOUT_US_1MBPS_BLE    (73)        /**< 1 Mb RX wait for acknowledgment time-out (combined with BLE). Smallest reliable value - 68.*/
+
+// Interrupt flags
+#define     NRF_ESB_INT_TX_SUCCESS_MSK          0x01        /**< Interrupt mask value for TX success. */
+#define     NRF_ESB_INT_TX_FAILED_MSK           0x02        /**< Interrupt mask value for TX failure. */
+#define     NRF_ESB_INT_RX_DATA_RECEIVED_MSK    0x04        /**< Interrupt mask value for RX_DR. */
+
+#define     NRF_ESB_PID_RESET_VALUE             0xFF        /**< Invalid PID value which is guaranteed to not collide with any valid PID value. */
+#define     NRF_ESB_PID_MAX                     3           /**< Maximum value for PID. */
+#define     NRF_ESB_CRC_RESET_VALUE             0xFFFF      /**< CRC reset value. */
+
+// Internal Enhanced ShockBurst module state.
+typedef enum {
+    NRF_ESB_STATE_IDLE,                                     /**< Module idle. */
+    NRF_ESB_STATE_PTX_TX,                                   /**< Module transmitting without acknowledgment. */
+    NRF_ESB_STATE_PTX_TX_ACK,                               /**< Module transmitting with acknowledgment. */
+    NRF_ESB_STATE_PTX_RX_ACK,                               /**< Module transmitting with acknowledgment and reception of payload with the acknowledgment response. */
+    NRF_ESB_STATE_PRX,                                      /**< Module receiving packets without acknowledgment. */
+    NRF_ESB_STATE_PRX_SEND_ACK,                             /**< Module transmitting acknowledgment in RX mode. */
+} nrf_esb_mainstate_t;
+
+
+#define DISABLE_RF_IRQ()      NVIC_DisableIRQ(RADIO_IRQn)
+#define ENABLE_RF_IRQ()       NVIC_EnableIRQ(RADIO_IRQn)
+
+#define _RADIO_SHORTS_COMMON ( RADIO_SHORTS_READY_START_Msk | RADIO_SHORTS_END_DISABLE_Msk | \
+            RADIO_SHORTS_ADDRESS_RSSISTART_Msk | RADIO_SHORTS_DISABLED_RSSISTOP_Msk )
+
+#define VERIFY_PAYLOAD_LENGTH(p)                            \
+do                                                          \
+{                                                           \
+    if (p->length == 0 ||                                    \
+       p->length > NRF_ESB_MAX_PAYLOAD_LENGTH ||            \
+       (m_config_local.protocol == NRF_ESB_PROTOCOL_ESB &&  \
+        p->length > m_config_local.payload_length))         \
+    {                                                       \
+        return NRF_ERROR_INVALID_LENGTH;                    \
+    }                                                       \
+}while (0)
+
+
+/* @brief Structure holding pipe info PID and CRC and acknowledgment payload. */
+typedef struct
+{
+    uint16_t    crc;                                      /**< CRC value of the last received packet (Used to detect retransmits). */
+    uint8_t     pid;                                      /**< Packet ID of the last received packet (Used to detect retransmits). */
+    bool        ack_payload;                              /**< Flag indicating the state of the transmission of acknowledgment payloads. */
+} pipe_info_t;
+
+
+/* @brief  First-in, first-out queue of payloads to be transmitted. */
+typedef struct
+{
+    nrf_esb_payload_t * p_payload[NRF_ESB_TX_FIFO_SIZE];  /**< Pointer to the actual queue. */
+    uint32_t            entry_point;                      /**< Current start of queue. */
+    uint32_t            exit_point;                       /**< Current end of queue. */
+    uint32_t            count;                            /**< Current number of elements in the queue. */
+} nrf_esb_payload_tx_fifo_t;
+
+
+/* @brief First-in, first-out queue of received payloads. */
+typedef struct
+{
+    nrf_esb_payload_t * p_payload[NRF_ESB_RX_FIFO_SIZE];  /**< Pointer to the actual queue. */
+    uint32_t            entry_point;                      /**< Current start of queue. */
+    uint32_t            exit_point;                       /**< Current end of queue. */
+    uint32_t            count;                            /**< Current number of elements in the queue. */
+} nrf_esb_payload_rx_fifo_t;
+
+
+/**@brief Enhanced ShockBurst address.
+ *
+ * Enhanced ShockBurst addresses consist of a base address and a prefix
+ *          that is unique for each pipe. See @ref esb_addressing in the ESB user
+ *          guide for more information.
+*/
+typedef struct
+{
+    uint8_t base_addr_p0[4];        /**< Base address for pipe 0 encoded in big endian. */
+    uint8_t base_addr_p1[4];        /**< Base address for pipe 1-7 encoded in big endian. */
+    uint8_t pipe_prefixes[8];       /**< Address prefix for pipe 0 to 7. */
+    uint8_t num_pipes;              /**< Number of pipes available. */
+    uint8_t addr_length;            /**< Length of the address including the prefix. */
+    uint8_t rx_pipes_enabled;       /**< Bitfield for enabled pipes. */
+    uint8_t rf_channel;             /**< Channel to use (must be between 0 and 100). */
+} nrf_esb_address_t;
+
+
+// Module state
+static bool                         m_esb_initialized           = false;
+static nrf_esb_mainstate_t          m_nrf_esb_mainstate         = NRF_ESB_STATE_IDLE;
+static nrf_esb_payload_t          * mp_current_payload;
+
+static nrf_esb_event_handler_t      m_event_handler;
+
+// Address parameters
+__ALIGN(4) static nrf_esb_address_t m_esb_addr = NRF_ESB_ADDR_DEFAULT;
+
+// RF parameters
+static nrf_esb_config_t             m_config_local;
+
+// TX FIFO
+static nrf_esb_payload_t            m_tx_fifo_payload[NRF_ESB_TX_FIFO_SIZE];
+static nrf_esb_payload_tx_fifo_t    m_tx_fifo;
+
+// RX FIFO
+static nrf_esb_payload_t            m_rx_fifo_payload[NRF_ESB_RX_FIFO_SIZE];
+static nrf_esb_payload_rx_fifo_t    m_rx_fifo;
+
+// Payload buffers
+static  uint8_t                     m_tx_payload_buffer[NRF_ESB_MAX_PAYLOAD_LENGTH + 2];
+static  uint8_t                     m_rx_payload_buffer[NRF_ESB_MAX_PAYLOAD_LENGTH + 2];
+
+// Run time variables
+static volatile uint32_t            m_interrupt_flags = 0;
+static uint8_t                      m_pids[NRF_ESB_PIPE_COUNT];
+static pipe_info_t                  m_rx_pipe_info[NRF_ESB_PIPE_COUNT];
+static volatile uint32_t            m_retransmits_remaining;
+static volatile uint32_t            m_last_tx_attempts;
+static volatile uint32_t            m_wait_for_ack_timeout_us;
+
+// nRF52 address workaround enable
+#ifdef NRF52
+static bool                         m_address_hang_fix_enable = true;
+#endif
+static uint32_t                     m_radio_shorts_common = _RADIO_SHORTS_COMMON;
+
+// These function pointers are changed dynamically, depending on protocol configuration and state.
+static void (*on_radio_disabled)(void) = 0;
+static void (*on_radio_end)(void) = 0;
+static void (*update_rf_payload_format)(uint32_t payload_length) = 0;
+
+
+// The following functions are assigned to the function pointers above.
+static void on_radio_disabled_tx_noack(void);
+static void on_radio_disabled_tx(void);
+static void on_radio_disabled_tx_wait_for_ack(void);
+static void on_radio_disabled_rx(void);
+static void on_radio_disabled_rx_ack(void);
+
+
+#define NRF_ESB_ADDR_UPDATE_MASK_BASE0          (1 << 0)    /*< Mask value to signal updating BASE0 radio address. */
+#define NRF_ESB_ADDR_UPDATE_MASK_BASE1          (1 << 1)    /*< Mask value to signal updating BASE1 radio address. */
+#define NRF_ESB_ADDR_UPDATE_MASK_PREFIX         (1 << 2)    /*< Mask value to signal updating radio prefixes. */
+
+
+// Function to do bytewise bit-swap on an unsigned 32-bit value
+static uint32_t bytewise_bit_swap(uint8_t const * p_inp)
+{
+    uint32_t inp = (*(uint32_t*)p_inp);
+#if __CORTEX_M == (0x04U)
+    return __REV((uint32_t)__RBIT(inp)); //lint -esym(628, __rev) -esym(526, __rev) -esym(628, __rbit) -esym(526, __rbit) */
+#else
+    inp = (inp & 0xF0F0F0F0) >> 4 | (inp & 0x0F0F0F0F) << 4;
+    inp = (inp & 0xCCCCCCCC) >> 2 | (inp & 0x33333333) << 2;
+    inp = (inp & 0xAAAAAAAA) >> 1 | (inp & 0x55555555) << 1;
+    return inp;
+#endif
+}
+
+
+// Internal function to convert base addresses from nRF24L type addressing to nRF51 type addressing
+static uint32_t addr_conv(uint8_t const* p_addr)
+{
+    return __REV(bytewise_bit_swap(p_addr)); //lint -esym(628, __rev) -esym(526, __rev) */
+}
+
+
+static ret_code_t apply_address_workarounds()
+{
+#ifdef NRF52
+    //  Set up radio parameters.
+    NRF_RADIO->MODECNF0 = (NRF_RADIO->MODECNF0 & ~RADIO_MODECNF0_RU_Msk) | RADIO_MODECNF0_RU_Default << RADIO_MODECNF0_RU_Pos;
+
+    // Workaround for nRF52832 Rev 1 Errata 102 and nRF52832 Rev 1 Errata 106. This will reduce sensitivity by 3dB.
+    *((volatile uint32_t *)0x40001774) = (*((volatile uint32_t *)0x40001774) & 0xFFFFFFFE) | 0x01000000;
+#endif
+    return NRF_SUCCESS;
+}
+
+
+static void update_rf_payload_format_esb_dpl(uint32_t payload_length)
+{
+#if (NRF_ESB_MAX_PAYLOAD_LENGTH <= 32)
+    // Using 6 bits for length
+    NRF_RADIO->PCNF0 = (0 << RADIO_PCNF0_S0LEN_Pos) |
+                       (6 << RADIO_PCNF0_LFLEN_Pos) |
+                       (3 << RADIO_PCNF0_S1LEN_Pos) ;
+#else
+    // Using 8 bits for length
+    NRF_RADIO->PCNF0 = (0 << RADIO_PCNF0_S0LEN_Pos) |
+                       (8 << RADIO_PCNF0_LFLEN_Pos) |
+                       (3 << RADIO_PCNF0_S1LEN_Pos) ;
+#endif
+    NRF_RADIO->PCNF1 = (RADIO_PCNF1_WHITEEN_Disabled    << RADIO_PCNF1_WHITEEN_Pos) |
+                       (RADIO_PCNF1_ENDIAN_Big          << RADIO_PCNF1_ENDIAN_Pos)  |
+                       ((m_esb_addr.addr_length - 1)    << RADIO_PCNF1_BALEN_Pos)   |
+                       (0                               << RADIO_PCNF1_STATLEN_Pos) |
+                       (NRF_ESB_MAX_PAYLOAD_LENGTH      << RADIO_PCNF1_MAXLEN_Pos);
+}
+
+
+static void update_rf_payload_format_esb(uint32_t payload_length)
+{
+    NRF_RADIO->PCNF0 = (1 << RADIO_PCNF0_S0LEN_Pos) |
+                       (0 << RADIO_PCNF0_LFLEN_Pos) |
+                       (1 << RADIO_PCNF0_S1LEN_Pos);
+
+    NRF_RADIO->PCNF1 = (RADIO_PCNF1_WHITEEN_Disabled    << RADIO_PCNF1_WHITEEN_Pos) |
+                       (RADIO_PCNF1_ENDIAN_Big          << RADIO_PCNF1_ENDIAN_Pos)  |
+                       ((m_esb_addr.addr_length - 1)    << RADIO_PCNF1_BALEN_Pos)   |
+                       (payload_length                  << RADIO_PCNF1_STATLEN_Pos) |
+                       (payload_length                  << RADIO_PCNF1_MAXLEN_Pos);
+}
+
+
+static void update_radio_addresses(uint8_t update_mask)
+{
+    if ((update_mask & NRF_ESB_ADDR_UPDATE_MASK_BASE0) != 0)
+    {
+        NRF_RADIO->BASE0 = addr_conv(m_esb_addr.base_addr_p0);
+    }
+
+    if ((update_mask & NRF_ESB_ADDR_UPDATE_MASK_BASE1) != 0)
+    {
+        NRF_RADIO->BASE1 = addr_conv(m_esb_addr.base_addr_p1);
+    }
+
+    if ((update_mask & NRF_ESB_ADDR_UPDATE_MASK_PREFIX) != 0)
+    {
+        NRF_RADIO->PREFIX0 = bytewise_bit_swap(&m_esb_addr.pipe_prefixes[0]);
+        NRF_RADIO->PREFIX1 = bytewise_bit_swap(&m_esb_addr.pipe_prefixes[4]);
+    }
+}
+
+
+static void update_radio_tx_power()
+{
+    NRF_RADIO->TXPOWER = m_config_local.tx_output_power << RADIO_TXPOWER_TXPOWER_Pos;
+}
+
+
+static bool update_radio_bitrate()
+{
+    NRF_RADIO->MODE = m_config_local.bitrate << RADIO_MODE_MODE_Pos;
+
+    switch (m_config_local.bitrate)
+    {
+        case NRF_ESB_BITRATE_2MBPS:
+#ifdef NRF52
+        case NRF_ESB_BITRATE_2MBPS_BLE:
+#endif
+            m_wait_for_ack_timeout_us = RX_WAIT_FOR_ACK_TIMEOUT_US_2MBPS;
+            break;
+
+        case NRF_ESB_BITRATE_1MBPS:
+            m_wait_for_ack_timeout_us = RX_WAIT_FOR_ACK_TIMEOUT_US_1MBPS;
+            break;
+
+#ifdef NRF51
+        case NRF_ESB_BITRATE_250KBPS:
+            m_wait_for_ack_timeout_us = RX_WAIT_FOR_ACK_TIMEOUT_US_250KBPS;
+            break;
+#endif
+        
+        case NRF_ESB_BITRATE_1MBPS_BLE:
+            m_wait_for_ack_timeout_us = RX_WAIT_FOR_ACK_TIMEOUT_US_1MBPS_BLE;
+            break;
+
+        default:
+            // Should not be reached
+            return false;
+    }
+    return true;
+}
+
+
+static bool update_radio_protocol()
+{
+    switch (m_config_local.protocol)
+    {
+        case NRF_ESB_PROTOCOL_ESB_DPL:
+            update_rf_payload_format = update_rf_payload_format_esb_dpl;
+            break;
+
+        case NRF_ESB_PROTOCOL_ESB:
+            update_rf_payload_format = update_rf_payload_format_esb;
+            break;
+
+        default:
+            // Should not be reached
+            return false;
+    }
+    return true;
+}
+
+
+static bool update_radio_crc()
+{
+    switch(m_config_local.crc)
+    {
+        case NRF_ESB_CRC_16BIT:
+            NRF_RADIO->CRCINIT = 0xFFFFUL;      // Initial value
+            NRF_RADIO->CRCPOLY = 0x11021UL;     // CRC poly: x^16+x^12^x^5+1
+            break;
+        
+        case NRF_ESB_CRC_8BIT:
+            NRF_RADIO->CRCINIT = 0xFFUL;        // Initial value
+            NRF_RADIO->CRCPOLY = 0x107UL;       // CRC poly: x^8+x^2^x^1+1
+            break;
+        
+        case NRF_ESB_CRC_OFF:
+            break;
+        
+        default:
+            return false;
+    }
+    NRF_RADIO->CRCCNF = m_config_local.crc << RADIO_CRCCNF_LEN_Pos;
+    return true;
+}
+
+
+static bool update_radio_parameters()
+{
+    bool params_valid = true;
+    update_radio_tx_power();
+    params_valid &= update_radio_bitrate();
+    params_valid &= update_radio_protocol();
+    params_valid &= update_radio_crc();
+    update_rf_payload_format(m_config_local.payload_length);
+    params_valid &= (m_config_local.retransmit_delay >= NRF_ESB_RETRANSMIT_DELAY_MIN);
+    return params_valid;
+}
+
+
+static void reset_fifos()
+{
+    m_tx_fifo.entry_point = 0;
+    m_tx_fifo.exit_point  = 0;
+    m_tx_fifo.count       = 0;
+
+    m_rx_fifo.entry_point = 0;
+    m_rx_fifo.exit_point  = 0;
+    m_rx_fifo.count       = 0;
+}
+
+
+static void initialize_fifos()
+{
+    reset_fifos();
+
+    for (int i = 0; i < NRF_ESB_TX_FIFO_SIZE; i++)
+    {
+        m_tx_fifo.p_payload[i] = &m_tx_fifo_payload[i];
+    }
+
+    for (int i = 0; i < NRF_ESB_RX_FIFO_SIZE; i++)
+    {
+        m_rx_fifo.p_payload[i] = &m_rx_fifo_payload[i];
+    }
+}
+
+
+static void tx_fifo_remove_last()
+{
+    if (m_tx_fifo.count > 0)
+    {
+        DISABLE_RF_IRQ();
+
+        m_tx_fifo.count--;
+        if (++m_tx_fifo.exit_point >= NRF_ESB_TX_FIFO_SIZE)
+        {
+            m_tx_fifo.exit_point = 0;
+        }
+
+        ENABLE_RF_IRQ();
+    }
+}
+
+/** @brief  Function to push the content of the rx_buffer to the RX FIFO.
+ *
+ *  The module will point the register NRF_RADIO->PACKETPTR to a buffer for receiving packets.
+ *  After receiving a packet the module will call this function to copy the received data to
+ *  the RX FIFO.
+ *
+ *  @param  pipe Pipe number to set for the packet.
+ *  @param  pid  Packet ID.
+ *
+ *  @retval true   Operation successful.
+ *  @retval false  Operation failed.
+ */
+static bool rx_fifo_push_rfbuf(uint8_t pipe, uint8_t pid)
+{
+    if (m_rx_fifo.count < NRF_ESB_RX_FIFO_SIZE)
+    {
+        if (m_config_local.protocol == NRF_ESB_PROTOCOL_ESB_DPL)
+        {
+            if (m_rx_payload_buffer[0] > NRF_ESB_MAX_PAYLOAD_LENGTH)
+            {
+                return false;
+            }
+
+            m_rx_fifo.p_payload[m_rx_fifo.entry_point]->length = m_rx_payload_buffer[0];
+        }
+        else if (m_config_local.mode == NRF_ESB_MODE_PTX)
+        {
+            // Received packet is an acknowledgment
+            m_rx_fifo.p_payload[m_rx_fifo.entry_point]->length = 0;
+        }
+        else
+        {
+            m_rx_fifo.p_payload[m_rx_fifo.entry_point]->length = m_config_local.payload_length;
+        }
+
+        memcpy(m_rx_fifo.p_payload[m_rx_fifo.entry_point]->data, &m_rx_payload_buffer[2],
+               m_rx_fifo.p_payload[m_rx_fifo.entry_point]->length);
+
+        m_rx_fifo.p_payload[m_rx_fifo.entry_point]->pipe  = pipe;
+        m_rx_fifo.p_payload[m_rx_fifo.entry_point]->rssi  = NRF_RADIO->RSSISAMPLE;
+        m_rx_fifo.p_payload[m_rx_fifo.entry_point]->pid   = pid;
+        m_rx_fifo.p_payload[m_rx_fifo.entry_point]->noack = !(m_rx_payload_buffer[1] & 0x01);
+        if (++m_rx_fifo.entry_point >= NRF_ESB_RX_FIFO_SIZE)
+        {
+            m_rx_fifo.entry_point = 0;
+        }
+        m_rx_fifo.count++;
+
+        return true;
+    }
+
+    return false;
+}
+
+
+static void sys_timer_init()
+{
+    // Configure the system timer with a 1 MHz base frequency
+    NRF_ESB_SYS_TIMER->PRESCALER = 4;
+    NRF_ESB_SYS_TIMER->BITMODE   = TIMER_BITMODE_BITMODE_16Bit;
+    NRF_ESB_SYS_TIMER->SHORTS    = TIMER_SHORTS_COMPARE1_CLEAR_Msk | TIMER_SHORTS_COMPARE1_STOP_Msk;
+}
+
+
+static void ppi_init()
+{
+    NRF_PPI->CH[NRF_ESB_PPI_TIMER_START].EEP = (uint32_t)&NRF_RADIO->EVENTS_READY;
+    NRF_PPI->CH[NRF_ESB_PPI_TIMER_START].TEP = (uint32_t)&NRF_ESB_SYS_TIMER->TASKS_START;
+
+    NRF_PPI->CH[NRF_ESB_PPI_TIMER_STOP].EEP  = (uint32_t)&NRF_RADIO->EVENTS_ADDRESS;
+    NRF_PPI->CH[NRF_ESB_PPI_TIMER_STOP].TEP  = (uint32_t)&NRF_ESB_SYS_TIMER->TASKS_STOP;
+
+    NRF_PPI->CH[NRF_ESB_PPI_RX_TIMEOUT].EEP  = (uint32_t)&NRF_ESB_SYS_TIMER->EVENTS_COMPARE[0];
+    NRF_PPI->CH[NRF_ESB_PPI_RX_TIMEOUT].TEP  = (uint32_t)&NRF_RADIO->TASKS_DISABLE;
+
+    NRF_PPI->CH[NRF_ESB_PPI_TX_START].EEP    = (uint32_t)&NRF_ESB_SYS_TIMER->EVENTS_COMPARE[1];
+    NRF_PPI->CH[NRF_ESB_PPI_TX_START].TEP    = (uint32_t)&NRF_RADIO->TASKS_TXEN;
+}
+
+
+static void start_tx_transaction()
+{
+    bool ack;
+
+    m_last_tx_attempts = 1;
+    // Prepare the payload
+    mp_current_payload = m_tx_fifo.p_payload[m_tx_fifo.exit_point];
+
+
+    switch (m_config_local.protocol)
+    {
+        case NRF_ESB_PROTOCOL_ESB:
+            update_rf_payload_format(mp_current_payload->length);
+            m_tx_payload_buffer[0] = mp_current_payload->pid;
+            m_tx_payload_buffer[1] = 0;
+            memcpy(&m_tx_payload_buffer[2], mp_current_payload->data, mp_current_payload->length);
+
+            NRF_RADIO->SHORTS   = m_radio_shorts_common | RADIO_SHORTS_DISABLED_RXEN_Msk;
+            NRF_RADIO->INTENSET = RADIO_INTENSET_DISABLED_Msk | RADIO_INTENSET_READY_Msk;
+
+            // Configure the retransmit counter
+            m_retransmits_remaining = m_config_local.retransmit_count;
+            on_radio_disabled = on_radio_disabled_tx;
+            m_nrf_esb_mainstate = NRF_ESB_STATE_PTX_TX_ACK;
+            break;
+
+        case NRF_ESB_PROTOCOL_ESB_DPL:
+            ack = !mp_current_payload->noack || !m_config_local.selective_auto_ack;
+            m_tx_payload_buffer[0] = mp_current_payload->length;
+            m_tx_payload_buffer[1] = mp_current_payload->pid << 1;
+            m_tx_payload_buffer[1] |= mp_current_payload->noack ? 0x00 : 0x01;
+            memcpy(&m_tx_payload_buffer[2], mp_current_payload->data, mp_current_payload->length);
+
+            // Handling ack if noack is set to false or if selective auto ack is turned off
+            if (ack)
+            {
+                NRF_RADIO->SHORTS   = m_radio_shorts_common | RADIO_SHORTS_DISABLED_RXEN_Msk;
+                NRF_RADIO->INTENSET = RADIO_INTENSET_DISABLED_Msk | RADIO_INTENSET_READY_Msk;
+
+                // Configure the retransmit counter
+                m_retransmits_remaining = m_config_local.retransmit_count;
+                on_radio_disabled = on_radio_disabled_tx;
+                m_nrf_esb_mainstate = NRF_ESB_STATE_PTX_TX_ACK;
+            }
+            else
+            {
+                NRF_RADIO->SHORTS   = m_radio_shorts_common;
+                NRF_RADIO->INTENSET = RADIO_INTENSET_DISABLED_Msk;
+                on_radio_disabled   = on_radio_disabled_tx_noack;
+                m_nrf_esb_mainstate = NRF_ESB_STATE_PTX_TX;
+            }
+            break;
+
+        default:
+            // Should not be reached
+            break;
+    }
+
+    NRF_RADIO->TXADDRESS    = mp_current_payload->pipe;
+    NRF_RADIO->RXADDRESSES  = 1 << mp_current_payload->pipe;
+
+    NRF_RADIO->FREQUENCY    = m_esb_addr.rf_channel;
+    NRF_RADIO->PACKETPTR    = (uint32_t)m_tx_payload_buffer;
+
+    NVIC_ClearPendingIRQ(RADIO_IRQn);
+    NVIC_EnableIRQ(RADIO_IRQn);
+
+    NRF_RADIO->EVENTS_ADDRESS = 0;
+    NRF_RADIO->EVENTS_PAYLOAD = 0;
+    NRF_RADIO->EVENTS_DISABLED = 0;
+
+    DEBUG_PIN_SET(DEBUGPIN4);
+    NRF_RADIO->TASKS_TXEN  = 1;
+}
+
+
+static void on_radio_disabled_tx_noack()
+{
+    m_interrupt_flags |= NRF_ESB_INT_TX_SUCCESS_MSK;
+    tx_fifo_remove_last();
+
+    if (m_tx_fifo.count == 0)
+    {
+        m_nrf_esb_mainstate = NRF_ESB_STATE_IDLE;
+        NVIC_SetPendingIRQ(ESB_EVT_IRQ);
+    }
+    else
+    {
+        NVIC_SetPendingIRQ(ESB_EVT_IRQ);
+        start_tx_transaction();
+    }
+}
+
+
+static void on_radio_disabled_tx()
+{
+    // Remove the DISABLED -> RXEN shortcut, to make sure the radio stays
+    // disabled after the RX window
+    NRF_RADIO->SHORTS           = m_radio_shorts_common;
+
+    // Make sure the timer is started the next time the radio is ready,
+    // and that it will disable the radio automatically if no packet is
+    // received by the time defined in m_wait_for_ack_timeout_us
+    NRF_ESB_SYS_TIMER->CC[0]    = m_wait_for_ack_timeout_us;
+    NRF_ESB_SYS_TIMER->CC[1]    = m_config_local.retransmit_delay - 130;
+    NRF_ESB_SYS_TIMER->TASKS_CLEAR = 1;
+    NRF_ESB_SYS_TIMER->EVENTS_COMPARE[0] = 0;
+    NRF_ESB_SYS_TIMER->EVENTS_COMPARE[1] = 0;
+
+    NRF_PPI->CHENSET            = (1 << NRF_ESB_PPI_TIMER_START) |
+                                  (1 << NRF_ESB_PPI_RX_TIMEOUT) |
+                                  (1 << NRF_ESB_PPI_TIMER_STOP);
+    NRF_PPI->CHENCLR            = (1 << NRF_ESB_PPI_TX_START);
+    NRF_RADIO->EVENTS_END       = 0;
+
+    if (m_config_local.protocol == NRF_ESB_PROTOCOL_ESB)
+    {
+        update_rf_payload_format(0);
+    }
+
+    NRF_RADIO->PACKETPTR        = (uint32_t)m_rx_payload_buffer;
+    on_radio_disabled           = on_radio_disabled_tx_wait_for_ack;
+    m_nrf_esb_mainstate         = NRF_ESB_STATE_PTX_RX_ACK;
+}
+
+
+static void on_radio_disabled_tx_wait_for_ack()
+{
+    // This marks the completion of a TX_RX sequence (TX with ACK)
+
+    // Make sure the timer will not deactivate the radio if a packet is received
+    NRF_PPI->CHENCLR = (1 << NRF_ESB_PPI_TIMER_START) |
+                       (1 << NRF_ESB_PPI_RX_TIMEOUT)  |
+                       (1 << NRF_ESB_PPI_TIMER_STOP);
+
+    // If the radio has received a packet and the CRC status is OK
+    if (NRF_RADIO->EVENTS_END && NRF_RADIO->CRCSTATUS != 0)
+    {
+        NRF_ESB_SYS_TIMER->TASKS_STOP = 1;
+        NRF_PPI->CHENCLR = (1 << NRF_ESB_PPI_TX_START);
+        m_interrupt_flags |= NRF_ESB_INT_TX_SUCCESS_MSK;
+        m_last_tx_attempts = m_config_local.retransmit_count - m_retransmits_remaining + 1;
+
+        tx_fifo_remove_last();
+
+        if (m_config_local.protocol != NRF_ESB_PROTOCOL_ESB && m_rx_payload_buffer[0] > 0)
+        {
+            if (rx_fifo_push_rfbuf((uint8_t)NRF_RADIO->TXADDRESS, m_rx_payload_buffer[1] >> 1))
+            {
+                m_interrupt_flags |= NRF_ESB_INT_RX_DATA_RECEIVED_MSK;
+            }
+        }
+
+        if ((m_tx_fifo.count == 0) || (m_config_local.tx_mode == NRF_ESB_TXMODE_MANUAL))
+        {
+            m_nrf_esb_mainstate = NRF_ESB_STATE_IDLE;
+            NVIC_SetPendingIRQ(ESB_EVT_IRQ);
+        }
+        else
+        {
+            NVIC_SetPendingIRQ(ESB_EVT_IRQ);
+            start_tx_transaction();
+        }
+    }
+    else
+    {
+        if (m_retransmits_remaining-- == 0)
+        {
+            NRF_ESB_SYS_TIMER->TASKS_STOP = 1;
+            NRF_PPI->CHENCLR = (1 << NRF_ESB_PPI_TX_START);
+            // All retransmits are expended, and the TX operation is suspended
+            m_last_tx_attempts = m_config_local.retransmit_count + 1;
+            m_interrupt_flags |= NRF_ESB_INT_TX_FAILED_MSK;
+
+            m_nrf_esb_mainstate = NRF_ESB_STATE_IDLE;
+            NVIC_SetPendingIRQ(ESB_EVT_IRQ);
+        }
+        else
+        {
+            // There are still more retransmits left, TX mode should be
+            // entered again as soon as the system timer reaches CC[1].
+            NRF_RADIO->SHORTS = m_radio_shorts_common | RADIO_SHORTS_DISABLED_RXEN_Msk;
+            update_rf_payload_format(mp_current_payload->length);
+            NRF_RADIO->PACKETPTR = (uint32_t)m_tx_payload_buffer;
+            on_radio_disabled = on_radio_disabled_tx;
+            m_nrf_esb_mainstate = NRF_ESB_STATE_PTX_TX_ACK;
+            NRF_ESB_SYS_TIMER->TASKS_START = 1;
+            NRF_PPI->CHENSET = (1 << NRF_ESB_PPI_TX_START);
+            if (NRF_ESB_SYS_TIMER->EVENTS_COMPARE[1])
+            {
+                NRF_RADIO->TASKS_TXEN = 1;
+            }
+        }
+    }
+}
+
+static void clear_events_restart_rx(void)
+{
+    NRF_RADIO->SHORTS = m_radio_shorts_common;
+    update_rf_payload_format(m_config_local.payload_length);
+    NRF_RADIO->PACKETPTR = (uint32_t)m_rx_payload_buffer;
+    NRF_RADIO->EVENTS_DISABLED = 0;
+    NRF_RADIO->TASKS_DISABLE = 1;
+
+    while (NRF_RADIO->EVENTS_DISABLED == 0);
+
+    NRF_RADIO->EVENTS_DISABLED = 0;
+    NRF_RADIO->SHORTS = m_radio_shorts_common | RADIO_SHORTS_DISABLED_TXEN_Msk;
+
+    NRF_RADIO->TASKS_RXEN = 1;
+}
+
+static void on_radio_disabled_rx(void)
+{
+    bool            ack                = false;
+    bool            retransmit_payload = false;
+    bool            send_rx_event      = true;
+    pipe_info_t *   p_pipe_info;
+
+    if (NRF_RADIO->CRCSTATUS == 0)
+    {
+        clear_events_restart_rx();
+        return;
+    }
+
+    if (m_rx_fifo.count >= NRF_ESB_RX_FIFO_SIZE)
+    {
+        clear_events_restart_rx();
+        return;
+    }
+
+    p_pipe_info = &m_rx_pipe_info[NRF_RADIO->RXMATCH];
+    if (NRF_RADIO->RXCRC             == p_pipe_info->crc &&
+        (m_rx_payload_buffer[1] >> 1) == p_pipe_info->pid
+       )
+    {
+        retransmit_payload = true;
+        send_rx_event = false;
+    }
+
+    p_pipe_info->pid = m_rx_payload_buffer[1] >> 1;
+    p_pipe_info->crc = NRF_RADIO->RXCRC;
+
+    if ((m_config_local.selective_auto_ack == false) || ((m_rx_payload_buffer[1] & 0x01) == 1))
+    {
+        ack = true;
+    }
+
+    if (ack)
+    {
+        NRF_RADIO->SHORTS = m_radio_shorts_common | RADIO_SHORTS_DISABLED_RXEN_Msk;
+
+        switch (m_config_local.protocol)
+        {
+            case NRF_ESB_PROTOCOL_ESB_DPL:
+                {
+                    if (m_tx_fifo.count > 0 &&
+                        (m_tx_fifo.p_payload[m_tx_fifo.exit_point]->pipe == NRF_RADIO->RXMATCH)
+                       )
+                    {
+                        // Pipe stays in ACK with payload until TX FIFO is empty
+                        // Do not report TX success on first ack payload or retransmit
+                        if (p_pipe_info->ack_payload == true && !retransmit_payload)
+                        {
+                            if (++m_tx_fifo.exit_point >= NRF_ESB_TX_FIFO_SIZE)
+                            {
+                                m_tx_fifo.exit_point = 0;
+                            }
+
+                            m_tx_fifo.count--;
+
+                            // ACK payloads also require TX_DS
+                            // (page 40 of the 'nRF24LE1_Product_Specification_rev1_6.pdf').
+                            m_interrupt_flags |= NRF_ESB_INT_TX_SUCCESS_MSK;
+                        }
+
+                        p_pipe_info->ack_payload = true;
+
+                        mp_current_payload = m_tx_fifo.p_payload[m_tx_fifo.exit_point];
+
+                        update_rf_payload_format(mp_current_payload->length);
+                        m_tx_payload_buffer[0] = mp_current_payload->length;
+                        memcpy(&m_tx_payload_buffer[2],
+                               mp_current_payload->data,
+                               mp_current_payload->length);
+                    }
+                    else
+                    {
+                        p_pipe_info->ack_payload = false;
+                        update_rf_payload_format(0);
+                        m_tx_payload_buffer[0] = 0;
+                    }
+
+                    m_tx_payload_buffer[1] = m_rx_payload_buffer[1];
+                }
+                break;
+
+            case NRF_ESB_PROTOCOL_ESB:
+                {
+                    update_rf_payload_format(0);
+                    m_tx_payload_buffer[0] = m_rx_payload_buffer[0];
+                    m_tx_payload_buffer[1] = 0;
+                }
+                break;
+        }
+
+        m_nrf_esb_mainstate = NRF_ESB_STATE_PRX_SEND_ACK;
+        NRF_RADIO->TXADDRESS = NRF_RADIO->RXMATCH;
+        NRF_RADIO->PACKETPTR = (uint32_t)m_tx_payload_buffer;
+        on_radio_disabled = on_radio_disabled_rx_ack;
+    }
+    else
+    {
+        clear_events_restart_rx();
+    }
+
+    if (send_rx_event)
+    {
+        // Push the new packet to the RX buffer and trigger a received event if the operation was
+        // successful.
+        if (rx_fifo_push_rfbuf(NRF_RADIO->RXMATCH, p_pipe_info->pid))
+        {
+            m_interrupt_flags |= NRF_ESB_INT_RX_DATA_RECEIVED_MSK;
+            NVIC_SetPendingIRQ(ESB_EVT_IRQ);
+        }
+    }
+}
+
+
+static void on_radio_disabled_rx_ack(void)
+{
+    NRF_RADIO->SHORTS = m_radio_shorts_common | RADIO_SHORTS_DISABLED_TXEN_Msk;
+    update_rf_payload_format(m_config_local.payload_length);
+
+    NRF_RADIO->PACKETPTR = (uint32_t)m_rx_payload_buffer;
+    on_radio_disabled = on_radio_disabled_rx;
+
+    m_nrf_esb_mainstate = NRF_ESB_STATE_PRX;
+}
+
+
+/**@brief Function for clearing pending interrupts.
+ *
+ * @param[in,out]   p_interrupts        Pointer to the value that holds the current interrupts.
+ *
+ * @retval  NRF_SUCCESS                     If the interrupts were cleared successfully.
+ * @retval  NRF_ERROR_NULL                  If the required parameter was NULL.
+ * @retval  NRF_INVALID_STATE               If the module is not initialized.
+ */
+static uint32_t nrf_esb_get_clear_interrupts(uint32_t * p_interrupts)
+{
+    VERIFY_TRUE(m_esb_initialized, NRF_ERROR_INVALID_STATE);
+    VERIFY_PARAM_NOT_NULL(p_interrupts);
+
+    DISABLE_RF_IRQ();
+
+    *p_interrupts = m_interrupt_flags;
+    m_interrupt_flags = 0;
+
+    ENABLE_RF_IRQ();
+
+    return NRF_SUCCESS;
+}
+
+
+/*
+void RADIO_IRQHandler()
+{
+    if (NRF_RADIO->EVENTS_READY && (NRF_RADIO->INTENSET & RADIO_INTENSET_READY_Msk))
+    {
+        NRF_RADIO->EVENTS_READY = 0;
+        DEBUG_PIN_SET(DEBUGPIN1);
+    }
+
+    if (NRF_RADIO->EVENTS_END && (NRF_RADIO->INTENSET & RADIO_INTENSET_END_Msk))
+    {
+        NRF_RADIO->EVENTS_END = 0;
+        DEBUG_PIN_SET(DEBUGPIN2);
+
+        // Call the correct on_radio_end function, depending on the current protocol state
+        if (on_radio_end)
+        {
+            on_radio_end();
+        }
+    }
+
+    if (NRF_RADIO->EVENTS_DISABLED && (NRF_RADIO->INTENSET & RADIO_INTENSET_DISABLED_Msk))
+    {
+        NRF_RADIO->EVENTS_DISABLED = 0;
+        DEBUG_PIN_SET(DEBUGPIN3);
+
+        // Call the correct on_radio_disable function, depending on the current protocol state
+        if (on_radio_disabled)
+        {
+            on_radio_disabled();
+        }
+    }
+
+    DEBUG_PIN_CLR(DEBUGPIN1);
+    DEBUG_PIN_CLR(DEBUGPIN2);
+    DEBUG_PIN_CLR(DEBUGPIN3);
+    DEBUG_PIN_CLR(DEBUGPIN4);
+} */
+
+
+uint32_t nrf_esb_init(nrf_esb_config_t const * p_config)
+{
+    uint32_t err_code;
+
+    VERIFY_PARAM_NOT_NULL(p_config);
+
+    if (m_esb_initialized)
+    {
+        err_code = nrf_esb_disable();
+        if (err_code != NRF_SUCCESS)
+        {
+            return err_code;
+        }
+    }
+
+    m_event_handler = p_config->event_handler;
+
+    memcpy(&m_config_local, p_config, sizeof(nrf_esb_config_t));
+    
+    m_interrupt_flags    = 0;
+
+    memset(m_rx_pipe_info, 0, sizeof(m_rx_pipe_info));
+    memset(m_pids, 0, sizeof(m_pids));
+
+    VERIFY_TRUE(update_radio_parameters(), NRF_ERROR_INVALID_PARAM);
+
+    // Configure radio address registers according to ESB default values
+    NRF_RADIO->BASE0   = 0xE7E7E7E7;
+    NRF_RADIO->BASE1   = 0x43434343;
+    NRF_RADIO->PREFIX0 = 0x23C343E7;
+    NRF_RADIO->PREFIX1 = 0x13E363A3;
+    
+    initialize_fifos();
+
+    sys_timer_init();
+
+    ppi_init();
+
+    NVIC_SetPriority(RADIO_IRQn, m_config_local.radio_irq_priority & ESB_IRQ_PRIORITY_MSK);
+    NVIC_SetPriority(ESB_EVT_IRQ, m_config_local.event_irq_priority & ESB_IRQ_PRIORITY_MSK);
+    NVIC_EnableIRQ(ESB_EVT_IRQ);
+
+#ifdef NRF52
+    if(m_address_hang_fix_enable)
+    {
+        // Setup a timeout timer to start on an ADDRESS match, and stop on a BCMATCH event.
+        // If the BCMATCH event never occurs the CC[0] event will fire, and the timer interrupt will disable the radio to recover.
+        m_radio_shorts_common |= RADIO_SHORTS_ADDRESS_BCSTART_Msk;
+        NRF_RADIO->BCC = 2;
+        NRF_ESB_BUGFIX_TIMER->BITMODE = TIMER_BITMODE_BITMODE_32Bit << TIMER_BITMODE_BITMODE_Pos;
+        NRF_ESB_BUGFIX_TIMER->PRESCALER = 4;
+        NRF_ESB_BUGFIX_TIMER->CC[0] = 5;
+        NRF_ESB_BUGFIX_TIMER->SHORTS = TIMER_SHORTS_COMPARE0_STOP_Msk | TIMER_SHORTS_COMPARE0_CLEAR_Msk;
+        NRF_ESB_BUGFIX_TIMER->MODE = TIMER_MODE_MODE_Timer << TIMER_MODE_MODE_Pos;
+        NRF_ESB_BUGFIX_TIMER->INTENSET = TIMER_INTENSET_COMPARE0_Msk;
+        NRF_ESB_BUGFIX_TIMER->TASKS_CLEAR = 1;
+        NVIC_SetPriority(NRF_ESB_BUGFIX_TIMER_IRQn, 5);
+        NVIC_EnableIRQ(NRF_ESB_BUGFIX_TIMER_IRQn);
+
+        NRF_PPI->CH[NRF_ESB_PPI_BUGFIX1].EEP = (uint32_t)&NRF_RADIO->EVENTS_ADDRESS;
+        NRF_PPI->CH[NRF_ESB_PPI_BUGFIX1].TEP = (uint32_t)&NRF_ESB_BUGFIX_TIMER->TASKS_START;
+
+        NRF_PPI->CH[NRF_ESB_PPI_BUGFIX2].EEP = (uint32_t)&NRF_RADIO->EVENTS_BCMATCH;
+        NRF_PPI->CH[NRF_ESB_PPI_BUGFIX2].TEP = (uint32_t)&NRF_ESB_BUGFIX_TIMER->TASKS_STOP;
+
+        NRF_PPI->CH[NRF_ESB_PPI_BUGFIX3].EEP = (uint32_t)&NRF_RADIO->EVENTS_BCMATCH;
+        NRF_PPI->CH[NRF_ESB_PPI_BUGFIX3].TEP = (uint32_t)&NRF_ESB_BUGFIX_TIMER->TASKS_CLEAR;
+
+        NRF_PPI->CHENSET = (1 << NRF_ESB_PPI_BUGFIX1) | (1 << NRF_ESB_PPI_BUGFIX2) | (1 << NRF_ESB_PPI_BUGFIX3);
+    }
+#endif
+
+    m_nrf_esb_mainstate = NRF_ESB_STATE_IDLE;
+    m_esb_initialized = true;
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_suspend(void)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+
+    // Clear PPI
+    NRF_PPI->CHENCLR = (1 << NRF_ESB_PPI_TIMER_START) |
+                       (1 << NRF_ESB_PPI_TIMER_STOP)  |
+                       (1 << NRF_ESB_PPI_RX_TIMEOUT)  |
+                       (1 << NRF_ESB_PPI_TX_START);
+
+    m_nrf_esb_mainstate = NRF_ESB_STATE_IDLE;
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_disable(void)
+{
+    // Clear PPI
+    NRF_PPI->CHENCLR = (1 << NRF_ESB_PPI_TIMER_START) |
+                       (1 << NRF_ESB_PPI_TIMER_STOP)  |
+                       (1 << NRF_ESB_PPI_RX_TIMEOUT)  |
+                       (1 << NRF_ESB_PPI_TX_START);
+
+    m_nrf_esb_mainstate = NRF_ESB_STATE_IDLE;
+
+    reset_fifos();
+
+    memset(m_rx_pipe_info, 0, sizeof(m_rx_pipe_info));
+    memset(m_pids, 0, sizeof(m_pids));
+
+    // Disable the radio
+    NVIC_DisableIRQ(ESB_EVT_IRQ);
+    NRF_RADIO->SHORTS = RADIO_SHORTS_READY_START_Enabled << RADIO_SHORTS_READY_START_Pos |
+                        RADIO_SHORTS_END_DISABLE_Enabled << RADIO_SHORTS_END_DISABLE_Pos;
+
+    return NRF_SUCCESS;
+}
+
+
+bool nrf_esb_is_idle(void)
+{
+    return m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE;
+}
+
+
+void ESB_EVT_IRQHandler(void)
+{
+    ret_code_t      err_code;
+    uint32_t        interrupts;
+    nrf_esb_evt_t   event;
+
+    event.tx_attempts = m_last_tx_attempts;
+
+    err_code = nrf_esb_get_clear_interrupts(&interrupts);
+    if (err_code == NRF_SUCCESS && m_event_handler != 0)
+    {
+        if (interrupts & NRF_ESB_INT_TX_SUCCESS_MSK)
+        {
+            event.evt_id = NRF_ESB_EVENT_TX_SUCCESS;
+            m_event_handler(&event);
+        }
+        if (interrupts & NRF_ESB_INT_TX_FAILED_MSK)
+        {
+            event.evt_id = NRF_ESB_EVENT_TX_FAILED;
+            m_event_handler(&event);
+        }
+        if (interrupts & NRF_ESB_INT_RX_DATA_RECEIVED_MSK)
+        {
+            event.evt_id = NRF_ESB_EVENT_RX_RECEIVED;
+            m_event_handler(&event);
+        }
+    }
+}
+
+uint32_t nrf_esb_write_payload(nrf_esb_payload_t const * p_payload)
+{
+    VERIFY_TRUE(m_esb_initialized, NRF_ERROR_INVALID_STATE);
+    VERIFY_PARAM_NOT_NULL(p_payload);
+    VERIFY_PAYLOAD_LENGTH(p_payload);
+    VERIFY_FALSE(m_tx_fifo.count >= NRF_ESB_TX_FIFO_SIZE, NRF_ERROR_NO_MEM);
+    VERIFY_TRUE(p_payload->pipe < NRF_ESB_PIPE_COUNT, NRF_ERROR_INVALID_PARAM);
+
+    DISABLE_RF_IRQ();
+
+    memcpy(m_tx_fifo.p_payload[m_tx_fifo.entry_point], p_payload, sizeof(nrf_esb_payload_t));
+
+    m_pids[p_payload->pipe] = (m_pids[p_payload->pipe] + 1) % (NRF_ESB_PID_MAX + 1);
+    m_tx_fifo.p_payload[m_tx_fifo.entry_point]->pid = m_pids[p_payload->pipe];
+
+    if (++m_tx_fifo.entry_point >= NRF_ESB_TX_FIFO_SIZE)
+    {
+        m_tx_fifo.entry_point = 0;
+    }
+
+    m_tx_fifo.count++;
+
+    ENABLE_RF_IRQ();
+
+
+    if (m_config_local.mode == NRF_ESB_MODE_PTX &&
+        m_config_local.tx_mode == NRF_ESB_TXMODE_AUTO &&
+        m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE)
+    {
+        start_tx_transaction();
+    }
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_read_rx_payload(nrf_esb_payload_t * p_payload)
+{
+    VERIFY_TRUE(m_esb_initialized, NRF_ERROR_INVALID_STATE);
+    VERIFY_PARAM_NOT_NULL(p_payload);
+
+    if (m_rx_fifo.count == 0)
+    {
+        return NRF_ERROR_NOT_FOUND;
+    }
+
+    DISABLE_RF_IRQ();
+
+    p_payload->length = m_rx_fifo.p_payload[m_rx_fifo.exit_point]->length;
+    p_payload->pipe   = m_rx_fifo.p_payload[m_rx_fifo.exit_point]->pipe;
+    p_payload->rssi   = m_rx_fifo.p_payload[m_rx_fifo.exit_point]->rssi;
+    p_payload->pid    = m_rx_fifo.p_payload[m_rx_fifo.exit_point]->pid;
+    p_payload->noack  = m_rx_fifo.p_payload[m_rx_fifo.exit_point]->noack; 
+    memcpy(p_payload->data, m_rx_fifo.p_payload[m_rx_fifo.exit_point]->data, p_payload->length);
+
+    if (++m_rx_fifo.exit_point >= NRF_ESB_RX_FIFO_SIZE)
+    {
+        m_rx_fifo.exit_point = 0;
+    }
+
+    m_rx_fifo.count--;
+
+    ENABLE_RF_IRQ();
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_start_tx(void)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+
+    if (m_tx_fifo.count == 0)
+    {
+        return NRF_ERROR_BUFFER_EMPTY;
+    }
+
+    start_tx_transaction();
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_start_rx(void)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+
+    NRF_RADIO->INTENCLR = 0xFFFFFFFF;
+    NRF_RADIO->EVENTS_DISABLED = 0;
+    on_radio_disabled = on_radio_disabled_rx;
+
+    NRF_RADIO->SHORTS      = m_radio_shorts_common | RADIO_SHORTS_DISABLED_TXEN_Msk;
+    NRF_RADIO->INTENSET    = RADIO_INTENSET_DISABLED_Msk;
+    m_nrf_esb_mainstate    = NRF_ESB_STATE_PRX;
+
+    NRF_RADIO->RXADDRESSES  = m_esb_addr.rx_pipes_enabled;
+    NRF_RADIO->FREQUENCY    = m_esb_addr.rf_channel;
+    NRF_RADIO->PACKETPTR    = (uint32_t)m_rx_payload_buffer;
+
+    NVIC_ClearPendingIRQ(RADIO_IRQn);
+    NVIC_EnableIRQ(RADIO_IRQn);
+
+    NRF_RADIO->EVENTS_ADDRESS = 0;
+    NRF_RADIO->EVENTS_PAYLOAD = 0;
+    NRF_RADIO->EVENTS_DISABLED = 0;
+
+    NRF_RADIO->TASKS_RXEN  = 1;
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_stop_rx(void)
+{
+    if (m_nrf_esb_mainstate == NRF_ESB_STATE_PRX)
+    {
+        NRF_RADIO->SHORTS = 0;
+        NRF_RADIO->INTENCLR = 0xFFFFFFFF;
+        on_radio_disabled = NULL;
+        NRF_RADIO->EVENTS_DISABLED = 0;
+        NRF_RADIO->TASKS_DISABLE = 1;
+        while (NRF_RADIO->EVENTS_DISABLED == 0);
+        m_nrf_esb_mainstate = NRF_ESB_STATE_IDLE;
+
+        return NRF_SUCCESS;
+    }
+
+    return NRF_ESB_ERROR_NOT_IN_RX_MODE;
+}
+
+
+uint32_t nrf_esb_flush_tx(void)
+{
+    VERIFY_TRUE(m_esb_initialized, NRF_ERROR_INVALID_STATE);
+
+    DISABLE_RF_IRQ();
+
+    m_tx_fifo.count = 0;
+    m_tx_fifo.entry_point = 0;
+    m_tx_fifo.exit_point = 0;
+
+    ENABLE_RF_IRQ();
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_pop_tx(void)
+{
+    VERIFY_TRUE(m_esb_initialized, NRF_ERROR_INVALID_STATE);
+    VERIFY_TRUE(m_tx_fifo.count > 0, NRF_ERROR_BUFFER_EMPTY);
+
+    DISABLE_RF_IRQ();
+
+    if (++m_tx_fifo.entry_point >= NRF_ESB_TX_FIFO_SIZE)
+    {
+        m_tx_fifo.entry_point = 0;
+    }
+    m_tx_fifo.count--;
+
+    ENABLE_RF_IRQ();
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_flush_rx(void)
+{
+    VERIFY_TRUE(m_esb_initialized, NRF_ERROR_INVALID_STATE);
+
+    DISABLE_RF_IRQ();
+
+    m_rx_fifo.count = 0;
+    m_rx_fifo.entry_point = 0;
+    m_rx_fifo.exit_point = 0;
+
+    memset(m_rx_pipe_info, 0, sizeof(m_rx_pipe_info));
+
+    ENABLE_RF_IRQ();
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_set_address_length(uint8_t length)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+    VERIFY_TRUE(length > 2 && length < 6, NRF_ERROR_INVALID_PARAM);
+    
+    /* 
+    Workaround for nRF52832 Rev 1 Errata 107
+    Check if pipe 0 or pipe 1-7 has a 'zero address'.
+    Avoid using access addresses in the following pattern (where X is don't care): 
+    ADDRLEN=5 
+    BASE0 = 0x0000XXXX, PREFIX0 = 0xXXXXXX00 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0xXXXX00XX 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0xXX00XXXX 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0x00XXXXXX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXXXXXX00 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXXXX00XX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXX00XXXX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0x00XXXXXX 
+
+    ADDRLEN=4 
+    BASE0 = 0x00XXXXXX, PREFIX0 = 0xXXXXXX00 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0xXXXX00XX 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0xXX00XXXX 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0x00XXXXXX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXXXXXX00 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXXXX00XX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXX00XXXX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0x00XXXXXX
+    */
+    uint32_t base_address_mask = length == 5 ? 0xFFFF0000 : 0xFF000000;
+    if((NRF_RADIO->BASE0 & base_address_mask) == 0 && (NRF_RADIO->PREFIX0 & 0x000000FF) == 0)
+    {
+        return NRF_ERROR_INVALID_PARAM;
+    }
+    if((NRF_RADIO->BASE1 & base_address_mask) == 0 && ((NRF_RADIO->PREFIX0 & 0x0000FF00) == 0 ||(NRF_RADIO->PREFIX0 & 0x00FF0000) == 0 || (NRF_RADIO->PREFIX0 & 0xFF000000) == 0 ||
+       (NRF_RADIO->PREFIX1 & 0xFF000000) == 0 || (NRF_RADIO->PREFIX1 & 0x00FF0000) == 0 ||(NRF_RADIO->PREFIX1 & 0x0000FF00) == 0 || (NRF_RADIO->PREFIX1 & 0x000000FF) == 0))
+    {
+        return NRF_ERROR_INVALID_PARAM;
+    }
+    
+    m_esb_addr.addr_length = length;
+
+    update_rf_payload_format(m_config_local.payload_length);
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_set_base_address_0(uint8_t const * p_addr)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+    VERIFY_PARAM_NOT_NULL(p_addr);
+    
+    /*
+    Workaround for nRF52832 Rev 1 Errata 107
+    Check if pipe 0 or pipe 1-7 has a 'zero address'.
+    Avoid using access addresses in the following pattern (where X is don't care): 
+    ADDRLEN=5 
+    BASE0 = 0x0000XXXX, PREFIX0 = 0xXXXXXX00 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0xXXXX00XX 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0xXX00XXXX 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0x00XXXXXX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXXXXXX00 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXXXX00XX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXX00XXXX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0x00XXXXXX 
+
+    ADDRLEN=4 
+    BASE0 = 0x00XXXXXX, PREFIX0 = 0xXXXXXX00 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0xXXXX00XX 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0xXX00XXXX 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0x00XXXXXX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXXXXXX00 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXXXX00XX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXX00XXXX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0x00XXXXXX
+    */
+    uint32_t base_address_mask = m_esb_addr.addr_length == 5 ? 0xFFFF0000 : 0xFF000000;
+    if((addr_conv(p_addr) & base_address_mask) == 0 && (NRF_RADIO->PREFIX0 & 0x000000FF) == 0)
+    {
+        return NRF_ERROR_INVALID_PARAM;
+    }
+
+    memcpy(m_esb_addr.base_addr_p0, p_addr, 4);
+
+    update_radio_addresses(NRF_ESB_ADDR_UPDATE_MASK_BASE0);
+
+    return apply_address_workarounds();
+}
+
+
+uint32_t nrf_esb_set_base_address_1(uint8_t const * p_addr)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+    VERIFY_PARAM_NOT_NULL(p_addr);
+    
+    /*
+    Workaround for nRF52832 Rev 1 Errata 107
+    Check if pipe 0 or pipe 1-7 has a 'zero address'.
+    Avoid using access addresses in the following pattern (where X is don't care): 
+    ADDRLEN=5 
+    BASE0 = 0x0000XXXX, PREFIX0 = 0xXXXXXX00 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0xXXXX00XX 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0xXX00XXXX 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0x00XXXXXX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXXXXXX00 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXXXX00XX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXX00XXXX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0x00XXXXXX 
+
+    ADDRLEN=4 
+    BASE0 = 0x00XXXXXX, PREFIX0 = 0xXXXXXX00 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0xXXXX00XX 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0xXX00XXXX 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0x00XXXXXX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXXXXXX00 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXXXX00XX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXX00XXXX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0x00XXXXXX
+    */
+    uint32_t base_address_mask = m_esb_addr.addr_length == 5 ? 0xFFFF0000 : 0xFF000000;
+    if((addr_conv(p_addr) & base_address_mask) == 0 && ((NRF_RADIO->PREFIX0 & 0x0000FF00) == 0 ||(NRF_RADIO->PREFIX0 & 0x00FF0000) == 0 || (NRF_RADIO->PREFIX0 & 0xFF000000) == 0 ||
+       (NRF_RADIO->PREFIX1 & 0xFF000000) == 0 || (NRF_RADIO->PREFIX1 & 0x00FF0000) == 0 ||(NRF_RADIO->PREFIX1 & 0x0000FF00) == 0 || (NRF_RADIO->PREFIX1 & 0x000000FF) == 0))
+    {
+        return NRF_ERROR_INVALID_PARAM;
+    }
+    
+    memcpy(m_esb_addr.base_addr_p1, p_addr, 4);
+
+    update_radio_addresses(NRF_ESB_ADDR_UPDATE_MASK_BASE1);
+
+    return apply_address_workarounds();
+}
+
+
+uint32_t nrf_esb_set_prefixes(uint8_t const * p_prefixes, uint8_t num_pipes)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+    VERIFY_PARAM_NOT_NULL(p_prefixes);
+    VERIFY_TRUE(num_pipes < 9, NRF_ERROR_INVALID_PARAM);
+    
+    /*
+    Workaround for nRF52832 Rev 1 Errata 107
+    Check if pipe 0 or pipe 1-7 has a 'zero address'.
+    Avoid using access addresses in the following pattern (where X is don't care): 
+    ADDRLEN=5 
+    BASE0 = 0x0000XXXX, PREFIX0 = 0xXXXXXX00 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0xXXXX00XX 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0xXX00XXXX 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0x00XXXXXX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXXXXXX00 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXXXX00XX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXX00XXXX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0x00XXXXXX 
+
+    ADDRLEN=4 
+    BASE0 = 0x00XXXXXX, PREFIX0 = 0xXXXXXX00 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0xXXXX00XX 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0xXX00XXXX 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0x00XXXXXX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXXXXXX00 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXXXX00XX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXX00XXXX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0x00XXXXXX
+    */
+    uint32_t base_address_mask = m_esb_addr.addr_length == 5 ? 0xFFFF0000 : 0xFF000000;
+    if(num_pipes >= 1 && (NRF_RADIO->BASE0 & base_address_mask) == 0 && p_prefixes[0] == 0)
+    {
+        return NRF_ERROR_INVALID_PARAM;
+    }
+
+    if((NRF_RADIO->BASE1 & base_address_mask) == 0)
+    {
+        for (uint8_t i = 1; i < num_pipes; i++)
+        {
+            if (p_prefixes[i] == 0)
+            {
+                return NRF_ERROR_INVALID_PARAM;
+            }
+        }
+    }
+    
+    memcpy(m_esb_addr.pipe_prefixes, p_prefixes, num_pipes);
+    m_esb_addr.num_pipes = num_pipes;
+    m_esb_addr.rx_pipes_enabled = BIT_MASK_UINT_8(num_pipes);
+
+    update_radio_addresses(NRF_ESB_ADDR_UPDATE_MASK_PREFIX);
+
+    return apply_address_workarounds();
+}
+
+
+uint32_t nrf_esb_update_prefix(uint8_t pipe, uint8_t prefix)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+    VERIFY_TRUE(pipe < 8, NRF_ERROR_INVALID_PARAM);
+    
+    /*
+    Workaround for nRF52832 Rev 1 Errata 107
+    Check if pipe 0 or pipe 1-7 has a 'zero address'.
+    Avoid using access addresses in the following pattern (where X is don't care): 
+    ADDRLEN=5 
+    BASE0 = 0x0000XXXX, PREFIX0 = 0xXXXXXX00 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0xXXXX00XX 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0xXX00XXXX 
+    BASE1 = 0x0000XXXX, PREFIX0 = 0x00XXXXXX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXXXXXX00 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXXXX00XX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0xXX00XXXX 
+    BASE1 = 0x0000XXXX, PREFIX1 = 0x00XXXXXX 
+
+    ADDRLEN=4 
+    BASE0 = 0x00XXXXXX, PREFIX0 = 0xXXXXXX00 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0xXXXX00XX 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0xXX00XXXX 
+    BASE1 = 0x00XXXXXX, PREFIX0 = 0x00XXXXXX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXXXXXX00 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXXXX00XX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0xXX00XXXX 
+    BASE1 = 0x00XXXXXX, PREFIX1 = 0x00XXXXXX
+    */
+    uint32_t base_address_mask = m_esb_addr.addr_length == 5 ? 0xFFFF0000 : 0xFF000000;
+    if (pipe == 0)
+    {
+        if((NRF_RADIO->BASE0 & base_address_mask) == 0 && prefix == 0)
+        {
+            return NRF_ERROR_INVALID_PARAM;
+        }
+    }
+    else{
+        if((NRF_RADIO->BASE1 & base_address_mask) == 0 && prefix == 0)
+        {
+            return NRF_ERROR_INVALID_PARAM;
+        }
+    }
+    
+    m_esb_addr.pipe_prefixes[pipe] = prefix;
+
+    update_radio_addresses(NRF_ESB_ADDR_UPDATE_MASK_PREFIX);
+
+    return apply_address_workarounds();
+}
+
+
+uint32_t nrf_esb_enable_pipes(uint8_t enable_mask)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+
+    m_esb_addr.rx_pipes_enabled = enable_mask;
+
+    return apply_address_workarounds();
+}
+
+
+uint32_t nrf_esb_set_rf_channel(uint32_t channel)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+    VERIFY_TRUE(channel <= 100, NRF_ERROR_INVALID_PARAM);
+
+    m_esb_addr.rf_channel = channel;
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_get_rf_channel(uint32_t * p_channel)
+{
+    VERIFY_PARAM_NOT_NULL(p_channel);
+
+    *p_channel = m_esb_addr.rf_channel;
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_set_tx_power(nrf_esb_tx_power_t tx_output_power)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+
+    if ( m_config_local.tx_output_power != tx_output_power )
+    {
+        m_config_local.tx_output_power = tx_output_power;
+        update_radio_tx_power();
+    }
+
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_set_retransmit_delay(uint16_t delay)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+    VERIFY_TRUE(delay >= NRF_ESB_RETRANSMIT_DELAY_MIN, NRF_ERROR_INVALID_PARAM);
+
+    m_config_local.retransmit_delay = delay;
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_set_retransmit_count(uint16_t count)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+
+    m_config_local.retransmit_count = count;
+    return NRF_SUCCESS;
+}
+
+
+uint32_t nrf_esb_set_bitrate(nrf_esb_bitrate_t bitrate)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+
+    m_config_local.bitrate = bitrate;
+    return update_radio_bitrate() ? NRF_SUCCESS : NRF_ERROR_INVALID_PARAM;
+}
+
+
+uint32_t nrf_esb_reuse_pid(uint8_t pipe)
+{
+    VERIFY_TRUE(m_nrf_esb_mainstate == NRF_ESB_STATE_IDLE, NRF_ERROR_BUSY);
+    VERIFY_TRUE(pipe < 8, NRF_ERROR_INVALID_PARAM);
+
+    m_pids[pipe] = (m_pids[pipe] + NRF_ESB_PID_MAX) % (NRF_ESB_PID_MAX + 1);
+    return NRF_SUCCESS;
+}
+
+
+// Handler for 
+#ifdef NRF52
+void NRF_ESB_BUGFIX_TIMER_IRQHandler(void)
+{
+    if(NRF_ESB_BUGFIX_TIMER->EVENTS_COMPARE[0])
+    {
+        NRF_ESB_BUGFIX_TIMER->EVENTS_COMPARE[0] = 0;
+
+        // If the timeout timer fires and we are in the PTX receive ACK state, disable the radio
+        if(m_nrf_esb_mainstate == NRF_ESB_STATE_PTX_RX_ACK)
+        {
+            NRF_RADIO->TASKS_DISABLE = 1;
+        }
+    }
+}
+#endif
\ No newline at end of file
diff -r a01a54c0dc90 -r 66f95e364222 nrf_esb.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nrf_esb.h	Thu Feb 04 10:36:44 2021 +0000
@@ -0,0 +1,609 @@
+/**
+ * Copyright (c) 2016 - 2018, Nordic Semiconductor ASA
+ * 
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form, except as embedded into a Nordic
+ *    Semiconductor ASA integrated circuit in a product or a software update for
+ *    such product, must reproduce the above copyright notice, this list of
+ *    conditions and the following disclaimer in the documentation and/or other
+ *    materials provided with the distribution.
+ * 
+ * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
+ *    contributors may be used to endorse or promote products derived from this
+ *    software without specific prior written permission.
+ * 
+ * 4. This software, with or without modification, must only be used with a
+ *    Nordic Semiconductor ASA integrated circuit.
+ * 
+ * 5. Any software provided in binary form under this license must not be reverse
+ *    engineered, decompiled, modified and/or disassembled.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
+ * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
+ * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ */
+#ifndef __NRF_ESB_H
+#define __NRF_ESB_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include "nrf.h"
+#include "app_util.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** @defgroup nrf_esb Enhanced ShockBurst
+ * @{
+ * @ingroup proprietary_api
+ *
+ * @brief Enhanced ShockBurst (ESB) is a basic protocol that supports two-way data
+ *        packet communication including packet buffering, packet acknowledgment,
+ *        and automatic retransmission of lost packets.
+ */
+
+/** @name Debug pins
+ * @{
+ * @brief If NRF_ESB_DEBUG is defined, these GPIO pins can be used for debug timing.
+ */
+
+#define DEBUGPIN1   12 //!< If NRF_ESB_DEBUG is defined, this GPIO pin is set with every radio interrupt.
+#define DEBUGPIN2   13 //!< If NRF_ESB_DEBUG is defined, this GPIO pin is set with every NRF_RADIO->EVENTS_END.
+#define DEBUGPIN3   14 //!< If NRF_ESB_DEBUG is defined, this GPIO pin is set with every NRF_RADIO->EVENTS_DISABLED.
+#define DEBUGPIN4   15 //!< If NRF_ESB_DEBUG is defined, this GPIO pin is set when the radio is set to start transmission.
+
+
+#ifdef  NRF_ESB_DEBUG
+#define DEBUG_PIN_SET(a)    (NRF_GPIO->OUTSET = (1 << (a))) //!< Used internally to set debug pins.
+#define DEBUG_PIN_CLR(a)    (NRF_GPIO->OUTCLR = (1 << (a))) //!< Used internally to clear debug pins.
+#else
+#define DEBUG_PIN_SET(a) //!< Used internally to set debug pins.
+#define DEBUG_PIN_CLR(a) //!< Used internally to clear debug pins.
+#endif
+
+  /** @} */
+  
+#define     NRF_ESB_RETRANSMIT_DELAY_MIN        135
+
+// Hardcoded parameters - change if necessary
+#ifndef NRF_ESB_MAX_PAYLOAD_LENGTH
+#define     NRF_ESB_MAX_PAYLOAD_LENGTH          32                  //!< The maximum size of the payload. Valid values are 1 to 252.
+#endif
+
+#define     NRF_ESB_TX_FIFO_SIZE                8                   //!< The size of the transmission first-in, first-out buffer.
+#define     NRF_ESB_RX_FIFO_SIZE                8                   //!< The size of the reception first-in, first-out buffer.
+
+// 252 is the largest possible payload size according to the nRF5 architecture.
+STATIC_ASSERT(NRF_ESB_MAX_PAYLOAD_LENGTH <= 252);
+
+#define     NRF_ESB_SYS_TIMER                   NRF_TIMER2          //!< The timer that is used by the module.
+#define     NRF_ESB_SYS_TIMER_IRQ_Handler       TIMER2_IRQHandler   //!< The handler that is used by @ref NRF_ESB_SYS_TIMER.
+
+#define     NRF_ESB_PPI_TIMER_START             10                  //!< The PPI channel used for starting the timer.
+#define     NRF_ESB_PPI_TIMER_STOP              11                  //!< The PPI channel used for stopping the timer.
+#define     NRF_ESB_PPI_RX_TIMEOUT              12                  //!< The PPI channel used for RX time-out.
+#define     NRF_ESB_PPI_TX_START                13                  //!< The PPI channel used for starting TX.
+
+/**@cond NO_DOXYGEN */
+
+// nRF52 address fix timer and PPI defines
+#ifdef NRF52
+#define     NRF_ESB_PPI_BUGFIX1                 9
+#define     NRF_ESB_PPI_BUGFIX2                 8
+#define     NRF_ESB_PPI_BUGFIX3                 7
+
+#define     NRF_ESB_BUGFIX_TIMER                NRF_TIMER3
+#define     NRF_ESB_BUGFIX_TIMER_IRQn           TIMER3_IRQn
+#define     NRF_ESB_BUGFIX_TIMER_IRQHandler     TIMER3_IRQHandler
+#endif
+
+/** @endcond */
+
+// Interrupt flags
+#define     NRF_ESB_INT_TX_SUCCESS_MSK          0x01                //!< The flag used to indicate a success since the last event.
+#define     NRF_ESB_INT_TX_FAILED_MSK           0x02                //!< The flag used to indicate a failure since the last event.
+#define     NRF_ESB_INT_RX_DR_MSK               0x04                //!< The flag used to indicate that a packet was received since the last event.
+
+#define     NRF_ESB_PID_RESET_VALUE             0xFF                //!< Invalid PID value that is guaranteed to not collide with any valid PID value.
+#define     NRF_ESB_PID_MAX                     3                   //!< The maximum value for PID.
+#define     NRF_ESB_CRC_RESET_VALUE             0xFFFF              //!< The CRC reset value.
+
+#define     ESB_EVT_IRQ                         SWI0_IRQn           //!< The ESB event IRQ number when running on an nRF5 device.
+#define     ESB_EVT_IRQHandler                  SWI0_IRQHandler     //!< The handler for @ref ESB_EVT_IRQ when running on an nRF5 device.
+
+#if defined(NRF52)
+#define ESB_IRQ_PRIORITY_MSK                    0x07                //!< The mask used to enforce a valid IRQ priority.
+#else
+#define ESB_IRQ_PRIORITY_MSK                    0x03                //!< The mask used to enforce a valid IRQ priority.
+#endif
+
+/** @brief Default address configuration for ESB. 
+ *  @details Roughly equal to the nRF24Lxx default (except for the number of pipes, because more pipes are supported). */
+#define NRF_ESB_ADDR_DEFAULT                                                    \
+{                                                                               \
+    .base_addr_p0       = { 0xE7, 0xE7, 0xE7, 0xE7 },                           \
+    .base_addr_p1       = { 0xC2, 0xC2, 0xC2, 0xC2 },                           \
+    .pipe_prefixes      = { 0xE7, 0xC2, 0xC3, 0xC4, 0xC5, 0xC6, 0xC7, 0xC8 },   \
+    .addr_length        = 5,                                                    \
+    .num_pipes          = 8,                                                    \
+    .rf_channel         = 2,                                                    \
+    .rx_pipes_enabled   = 0xFF                                                  \
+}
+
+
+/** @brief Default radio parameters. 
+ *  @details Roughly equal to the nRF24Lxx default parameters (except for CRC, which is set to 16 bit, and protocol, which is set to DPL). */
+#define NRF_ESB_DEFAULT_CONFIG {.protocol               = NRF_ESB_PROTOCOL_ESB_DPL,         \
+                                .mode                   = NRF_ESB_MODE_PTX,                 \
+                                .event_handler          = 0,                                \
+                                .bitrate                = NRF_ESB_BITRATE_2MBPS,            \
+                                .crc                    = NRF_ESB_CRC_16BIT,                \
+                                .tx_output_power        = NRF_ESB_TX_POWER_0DBM,            \
+                                .retransmit_delay       = 250,                              \
+                                .retransmit_count       = 3,                                \
+                                .tx_mode                = NRF_ESB_TXMODE_AUTO,              \
+                                .radio_irq_priority     = 1,                                \
+                                .event_irq_priority     = 2,                                \
+                                .payload_length         = 32,                               \
+                                .selective_auto_ack     = false                             \
+}
+
+
+/** @brief Default legacy radio parameters. Identical to the nRF24Lxx defaults. */
+#define NRF_ESB_LEGACY_CONFIG  {.protocol               = NRF_ESB_PROTOCOL_ESB,             \
+                                .mode                   = NRF_ESB_MODE_PTX,                 \
+                                .event_handler          = 0,                                \
+                                .bitrate                = NRF_ESB_BITRATE_2MBPS,            \
+                                .crc                    = NRF_ESB_CRC_8BIT,                 \
+                                .tx_output_power        = NRF_ESB_TX_POWER_0DBM,            \
+                                .retransmit_delay       = 600,                              \
+                                .retransmit_count       = 3,                                \
+                                .tx_mode                = NRF_ESB_TXMODE_AUTO,              \
+                                .radio_irq_priority     = 1,                                \
+                                .event_irq_priority     = 2,                                \
+                                .payload_length         = 32,                               \
+                                .selective_auto_ack     = false                             \
+}
+
+
+/** @brief Macro to create an initializer for a TX data packet.
+ *
+ * @details This macro generates an initializer. Using the initializer is more efficient
+ *          than setting the individual parameters dynamically.
+ *
+ * @param[in]   _pipe   The pipe to use for the data packet.
+ * @param[in]   ...     Comma separated list of character data to put in the TX buffer.
+ *                      Supported values consist of 1 to 63 characters.
+ *
+ * @return  Initializer that sets up the pipe, length, and byte array for content of the TX data.
+ */
+#define NRF_ESB_CREATE_PAYLOAD(_pipe, ...)                                                  \
+        {.pipe = _pipe, .length = NUM_VA_ARGS(__VA_ARGS__), .data = {__VA_ARGS__}};         \
+        STATIC_ASSERT(NUM_VA_ARGS(__VA_ARGS__) > 0 && NUM_VA_ARGS(__VA_ARGS__) <= 63)
+
+
+/**@brief Enhanced ShockBurst protocols. */
+typedef enum {
+    NRF_ESB_PROTOCOL_ESB,      /**< Enhanced ShockBurst with fixed payload length.                                            */
+    NRF_ESB_PROTOCOL_ESB_DPL   /**< Enhanced ShockBurst with dynamic payload length.                                          */
+} nrf_esb_protocol_t;
+
+
+/**@brief Enhanced ShockBurst modes. */
+typedef enum {
+    NRF_ESB_MODE_PTX,          /**< Primary transmitter mode. */
+    NRF_ESB_MODE_PRX           /**< Primary receiver mode.    */
+} nrf_esb_mode_t;
+
+
+/**@brief Enhanced ShockBurst bitrate modes. */
+typedef enum {
+    NRF_ESB_BITRATE_2MBPS     = RADIO_MODE_MODE_Nrf_2Mbit,      /**< 2 Mb radio mode.                                                */
+    NRF_ESB_BITRATE_1MBPS     = RADIO_MODE_MODE_Nrf_1Mbit,      /**< 1 Mb radio mode.                                                */
+    NRF_ESB_BITRATE_250KBPS   = RADIO_MODE_MODE_Nrf_250Kbit,    /**< 250 Kb radio mode.                                              */
+    NRF_ESB_BITRATE_1MBPS_BLE = RADIO_MODE_MODE_Ble_1Mbit,      /**< 1 Mb radio mode using @e Bluetooth low energy radio parameters. */
+#if defined(NRF52)
+    NRF_ESB_BITRATE_2MBPS_BLE = 4                               /**< 2 Mb radio mode using @e Bluetooth low energy radio parameters. */
+#endif
+} nrf_esb_bitrate_t;
+
+
+/**@brief Enhanced ShockBurst CRC modes. */
+typedef enum {
+    NRF_ESB_CRC_16BIT = RADIO_CRCCNF_LEN_Two,                   /**< Use two-byte CRC. */
+    NRF_ESB_CRC_8BIT  = RADIO_CRCCNF_LEN_One,                   /**< Use one-byte CRC. */
+    NRF_ESB_CRC_OFF   = RADIO_CRCCNF_LEN_Disabled               /**< Disable CRC.      */
+} nrf_esb_crc_t;
+
+
+/**@brief Enhanced ShockBurst radio transmission power modes. */
+typedef enum {
+    NRF_ESB_TX_POWER_4DBM     = RADIO_TXPOWER_TXPOWER_Pos4dBm,  /**< 4 dBm radio transmit power.   */
+#if defined(NRF52)
+    NRF_ESB_TX_POWER_3DBM     = RADIO_TXPOWER_TXPOWER_Pos3dBm,  /**< 3 dBm radio transmit power.   */
+#endif
+    NRF_ESB_TX_POWER_0DBM     = RADIO_TXPOWER_TXPOWER_0dBm,     /**< 0 dBm radio transmit power.   */
+    NRF_ESB_TX_POWER_NEG4DBM  = RADIO_TXPOWER_TXPOWER_Neg4dBm,  /**< -4 dBm radio transmit power.  */
+    NRF_ESB_TX_POWER_NEG8DBM  = RADIO_TXPOWER_TXPOWER_Neg8dBm,  /**< -8 dBm radio transmit power.  */
+    NRF_ESB_TX_POWER_NEG12DBM = RADIO_TXPOWER_TXPOWER_Neg12dBm, /**< -12 dBm radio transmit power. */
+    NRF_ESB_TX_POWER_NEG16DBM = RADIO_TXPOWER_TXPOWER_Neg16dBm, /**< -16 dBm radio transmit power. */
+    NRF_ESB_TX_POWER_NEG20DBM = RADIO_TXPOWER_TXPOWER_Neg20dBm, /**< -20 dBm radio transmit power. */
+    NRF_ESB_TX_POWER_NEG30DBM = RADIO_TXPOWER_TXPOWER_Neg30dBm  /**< -30 dBm radio transmit power. */
+} nrf_esb_tx_power_t;
+
+
+/**@brief Enhanced ShockBurst transmission modes. */
+typedef enum {
+    NRF_ESB_TXMODE_AUTO,        /**< Automatic TX mode: When the TX FIFO contains packets and the radio is idle, packets are sent automatically. */
+    NRF_ESB_TXMODE_MANUAL,      /**< Manual TX mode: Packets are not sent until @ref nrf_esb_start_tx is called. This mode can be used to ensure consistent packet timing. */
+    NRF_ESB_TXMODE_MANUAL_START /**< Manual start TX mode: Packets are not sent until @ref nrf_esb_start_tx is called. Then, transmission continues automatically until the TX FIFO is empty. */
+} nrf_esb_tx_mode_t;
+
+
+/**@brief Enhanced ShockBurst event IDs used to indicate the type of the event. */
+typedef enum
+{
+    NRF_ESB_EVENT_TX_SUCCESS,   /**< Event triggered on TX success.     */
+    NRF_ESB_EVENT_TX_FAILED,    /**< Event triggered on TX failure.     */
+    NRF_ESB_EVENT_RX_RECEIVED   /**< Event triggered on RX received.    */
+} nrf_esb_evt_id_t;
+
+
+/**@brief Enhanced ShockBurst payload.
+ *
+ * @details The payload is used both for transmissions and for acknowledging a
+ *          received packet with a payload.
+*/
+typedef struct
+{
+    uint8_t length;                                 //!< Length of the packet (maximum value is @ref NRF_ESB_MAX_PAYLOAD_LENGTH).
+    uint8_t pipe;                                   //!< Pipe used for this payload.
+    int8_t  rssi;                                   //!< RSSI for the received packet.
+    uint8_t noack;                                  //!< Flag indicating that this packet will not be acknowledgement.
+    uint8_t pid;                                    //!< PID assigned during communication.
+    uint8_t data[NRF_ESB_MAX_PAYLOAD_LENGTH];       //!< The payload data.
+} nrf_esb_payload_t;
+
+
+/**@brief Enhanced ShockBurst event. */
+typedef struct
+{
+    nrf_esb_evt_id_t    evt_id;                     //!< Enhanced ShockBurst event ID.
+    uint32_t            tx_attempts;                //!< Number of TX retransmission attempts.
+} nrf_esb_evt_t;
+
+
+/**@brief Definition of the event handler for the module. */
+typedef void (* nrf_esb_event_handler_t)(nrf_esb_evt_t const * p_event);
+
+
+/**@brief Main configuration structure for the module. */
+typedef struct
+{
+    nrf_esb_protocol_t      protocol;               //!< Enhanced ShockBurst protocol.
+    nrf_esb_mode_t          mode;                   //!< Enhanced ShockBurst mode.
+    nrf_esb_event_handler_t event_handler;          //!< Enhanced ShockBurst event handler.
+
+    // General RF parameters
+    nrf_esb_bitrate_t       bitrate;                //!< Enhanced ShockBurst bitrate mode.
+    nrf_esb_crc_t           crc;                    //!< Enhanced ShockBurst CRC mode.
+
+    nrf_esb_tx_power_t      tx_output_power;        //!< Enhanced ShockBurst radio transmission power mode.
+
+    uint16_t                retransmit_delay;       //!< The delay between each retransmission of unacknowledged packets.
+    uint16_t                retransmit_count;       //!< The number of retransmission attempts before transmission fail.
+
+    // Control settings
+    nrf_esb_tx_mode_t       tx_mode;                //!< Enhanced ShockBurst transmission mode.
+
+    uint8_t                 radio_irq_priority;     //!< nRF radio interrupt priority.
+    uint8_t                 event_irq_priority;     //!< ESB event interrupt priority.
+    uint8_t                 payload_length;         //!< Length of the payload (maximum length depends on the platforms that are used on each side).
+
+    bool                    selective_auto_ack;     //!< Enable or disable selective auto acknowledgement.
+} nrf_esb_config_t;
+
+
+/**@brief Function for initializing the Enhanced ShockBurst module.
+ *
+ * @param  p_config     Parameters for initializing the module.
+ *
+ * @retval  NRF_SUCCESS             If initialization was successful.
+ * @retval  NRF_ERROR_NULL          If the @p p_config argument was NULL.
+ * @retval  NRF_ERROR_BUSY          If the function failed because the radio is busy.
+ */
+uint32_t nrf_esb_init(nrf_esb_config_t const * p_config);
+
+
+/**@brief Function for suspending the Enhanced ShockBurst module.
+ *
+ * Calling this function stops ongoing communications without changing the queues.
+ *
+ * @retval  NRF_SUCCESS             If Enhanced ShockBurst was suspended.
+ * @retval  NRF_ERROR_BUSY          If the function failed because the radio is busy.
+ */
+uint32_t nrf_esb_suspend(void);
+
+
+/**@brief Function for disabling the Enhanced ShockBurst module.
+ *
+ * Calling this function disables the Enhanced ShockBurst module immediately.
+ * Doing so might stop ongoing communications.
+ *
+ * @note All queues are flushed by this function.
+ *
+ * @retval  NRF_SUCCESS             If Enhanced ShockBurst was disabled.
+ */
+uint32_t nrf_esb_disable(void);
+
+
+/**@brief Function for checking if the Enhanced ShockBurst module is idle.
+ *
+ * @retval true                     If the module is idle.
+ * @retval false                    If the module is busy.
+ */
+bool nrf_esb_is_idle(void);
+
+
+/**@brief Function for writing a payload for transmission or acknowledgement.
+ *
+ * This function writes a payload that is added to the queue. When the module is in PTX mode, the
+ * payload is queued for a regular transmission. When the module is in PRX mode, the payload
+ * is queued for when a packet is received that requires an acknowledgement with payload.
+ *
+ * @param[in]   p_payload     Pointer to the structure that contains information and state of the payload.
+ *
+ * @retval  NRF_SUCCESS                     If the payload was successfully queued for writing.
+ * @retval  NRF_ERROR_NULL                  If the required parameter was NULL.
+ * @retval  NRF_INVALID_STATE               If the module is not initialized.
+ * @retval  NRF_ERROR_NOT_SUPPORTED         If @p p_payload->noack was false, but selective acknowledgement is not enabled.
+ * @retval  NRF_ERROR_NO_MEM                If the TX FIFO is full.
+ * @retval  NRF_ERROR_INVALID_LENGTH        If the payload length was invalid (zero or larger than the allowed maximum).
+ */
+uint32_t nrf_esb_write_payload(nrf_esb_payload_t const * p_payload);
+
+
+/**@brief Function for reading an RX payload.
+ *
+ * @param[in,out]   p_payload   Pointer to the structure that contains information and state of the payload.
+ *
+ * @retval  NRF_SUCCESS                     If the data was read successfully.
+ * @retval  NRF_ERROR_NULL                  If the required parameter was NULL.
+ * @retval  NRF_INVALID_STATE               If the module is not initialized.
+ */
+uint32_t nrf_esb_read_rx_payload(nrf_esb_payload_t * p_payload);
+
+
+/**@brief Function for starting transmission.
+ *
+ * @retval  NRF_SUCCESS                     If the TX started successfully.
+ * @retval  NRF_ERROR_BUFFER_EMPTY          If the TX did not start because the FIFO buffer is empty.
+ * @retval  NRF_ERROR_BUSY                  If the function failed because the radio is busy.
+ */
+uint32_t nrf_esb_start_tx(void);
+
+
+/**@brief Function for starting to transmit data from the FIFO buffer.
+ *
+ * @retval  NRF_SUCCESS                     If the transmission was started successfully.
+ * @retval  NRF_ERROR_BUSY                  If the function failed because the radio is busy.
+ */
+uint32_t nrf_esb_start_rx(void);
+
+
+/** @brief Function for stopping data reception.
+ *
+ * @retval  NRF_SUCCESS                     If data reception was stopped successfully.
+ * @retval  NRF_ESB_ERROR_NOT_IN_RX_MODE    If the function failed because the module is not in RX mode.
+ */
+uint32_t nrf_esb_stop_rx(void);
+
+
+/**@brief Function for removing remaining items from the TX buffer.
+ *
+ * This function clears the TX FIFO buffer.
+ *
+ * @retval  NRF_SUCCESS                     If pending items in the TX buffer were successfully cleared.
+ * @retval  NRF_INVALID_STATE               If the module is not initialized.
+ */
+uint32_t nrf_esb_flush_tx(void);
+
+
+/**@brief Function for removing the first item from the TX buffer.
+ *
+ * @retval  NRF_SUCCESS                     If the operation completed successfully.
+ * @retval  NRF_INVALID_STATE               If the module is not initialized.
+ * @retval  NRF_ERROR_BUFFER_EMPTY          If there are no items in the queue to remove.
+ */
+uint32_t nrf_esb_pop_tx(void);
+
+
+/**@brief Function for removing remaining items from the RX buffer.
+ *
+ * @retval  NRF_SUCCESS                     If the pending items in the RX buffer were successfully cleared.
+ * @retval  NRF_INVALID_STATE               If the module is not initialized.
+ */
+uint32_t nrf_esb_flush_rx(void);
+
+
+/**@brief Function for setting the length of the address.
+ *
+ * @param[in]       length              Length of the ESB address (in bytes).
+ *
+ * @retval  NRF_SUCCESS                      If the address length was set successfully.
+ * @retval  NRF_ERROR_INVALID_PARAM          If the address length was invalid.
+ * @retval  NRF_ERROR_BUSY                   If the function failed because the radio is busy.
+ */
+uint32_t nrf_esb_set_address_length(uint8_t length);
+
+
+/**@brief Function for setting the base address for pipe 0.
+ *
+ * @param[in]       p_addr      Pointer to the address data.
+ *
+ * @retval  NRF_SUCCESS                     If the base address was set successfully.
+ * @retval  NRF_ERROR_BUSY                  If the function failed because the radio is busy.
+ * @retval  NRF_ERROR_INVALID_PARAM         If the function failed because the address given was too close to a zero address.
+ * @retval  NRF_ERROR_NULL                  If the required parameter was NULL.
+ */
+uint32_t nrf_esb_set_base_address_0(uint8_t const * p_addr);
+
+
+/**@brief Function for setting the base address for pipe 1 to pipe 7.
+ *
+ * @param[in]       p_addr      Pointer to the address data.
+ *
+ * @retval  NRF_SUCCESS                     If the base address was set successfully.
+ * @retval  NRF_ERROR_BUSY                  If the function failed because the radio is busy.
+ * @retval  NRF_ERROR_INVALID_PARAM         If the function failed because the address given was too close to a zero address.
+ * @retval  NRF_ERROR_NULL                  If the required parameter was NULL.
+ */
+uint32_t nrf_esb_set_base_address_1(uint8_t const * p_addr);
+
+
+/**@brief Function for setting the number of pipes and the pipe prefix addresses.
+ *
+ * This function configures the number of available pipes, enables the pipes,
+ * and sets their prefix addresses.
+ *
+ * @param[in]   p_prefixes      Pointer to a char array that contains the prefix for each pipe.
+ * @param[in]   num_pipes       Number of pipes.
+ *
+ * @retval  NRF_SUCCESS                     If the prefix addresses were set successfully.
+ * @retval  NRF_ERROR_BUSY                  If the function failed because the radio is busy.
+ * @retval  NRF_ERROR_NULL                  If a required parameter was NULL.
+ * @retval  NRF_ERROR_INVALID_PARAM         If an invalid number of pipes was given or if the address given was too close to a zero address.
+ */
+uint32_t nrf_esb_set_prefixes(uint8_t const * p_prefixes, uint8_t num_pipes);
+
+
+/**@brief Function for enabling pipes.
+ *
+ * The @p enable_mask parameter must contain the same number of pipes as has been configured
+ * with @ref nrf_esb_set_prefixes.
+ *
+ * @param   enable_mask         Bitfield mask to enable or disable pipes. Setting a bit to
+ *                              0 disables the pipe. Setting a bit to 1 enables the pipe.
+ *
+ * @retval  NRF_SUCCESS                     If the pipes were enabled and disabled successfully.
+ * @retval  NRF_ERROR_BUSY                  If the function failed because the radio is busy.
+ * @retval  NRF_ERROR_INVALID_PARAM         If the function failed because the address given was too close to a zero address.
+ */
+uint32_t nrf_esb_enable_pipes(uint8_t enable_mask);
+
+
+/**@brief Function for updating the prefix for a pipe.
+ *
+ * @param   pipe    Pipe for which to set the prefix.
+ * @param   prefix  Prefix to set for the pipe.
+ *
+ * @retval  NRF_SUCCESS                         If the operation completed successfully.
+ * @retval  NRF_ERROR_BUSY                      If the function failed because the radio is busy.
+ * @retval  NRF_ERROR_INVALID_PARAM             If the given pipe number was invalid or if the address given was too close to a zero address.
+ */
+uint32_t nrf_esb_update_prefix(uint8_t pipe, uint8_t prefix);
+
+
+/** @brief Function for setting the channel to use for the radio.
+ *
+ * The module must be in an idle state to call this function. As a PTX, the
+ * application must wait for an idle state and as a PRX, the application must stop RX
+ * before changing the channel. After changing the channel, operation can be resumed.
+ *
+ * @param[in]   channel                         Channel to use for radio.
+ *
+ * @retval  NRF_SUCCESS                         If the operation completed successfully.
+ * @retval  NRF_INVALID_STATE                   If the module is not initialized.
+ * @retval  NRF_ERROR_BUSY                      If the module was not in idle state.
+ * @retval  NRF_ERROR_INVALID_PARAM             If the channel is invalid (larger than 100).
+ */
+uint32_t nrf_esb_set_rf_channel(uint32_t channel);
+
+
+/**@brief Function for getting the current radio channel.
+ *
+ * @param[in, out] p_channel    Pointer to the channel data.
+ *
+ * @retval  NRF_SUCCESS                         If the operation completed successfully.
+ * @retval  NRF_ERROR_NULL                      If the required parameter was NULL.
+ */
+uint32_t nrf_esb_get_rf_channel(uint32_t * p_channel);
+
+
+/**@brief Function for setting the radio output power.
+ *
+ * @param[in]   tx_output_power    Output power.
+ *
+ * @retval  NRF_SUCCESS                         If the operation completed successfully.
+ * @retval  NRF_ERROR_BUSY                      If the function failed because the radio is busy.
+ */
+uint32_t nrf_esb_set_tx_power(nrf_esb_tx_power_t tx_output_power);
+
+
+/**@brief Function for setting the packet retransmit delay.
+ *
+ * @param[in]   delay                           Delay between retransmissions.
+ *
+ * @retval  NRF_SUCCESS                         If the operation completed successfully.
+ * @retval  NRF_ERROR_BUSY                      If the function failed because the radio is busy.
+ */
+uint32_t nrf_esb_set_retransmit_delay(uint16_t delay);
+
+
+/**@brief Function for setting the number of retransmission attempts.
+ *
+ * @param[in]   count                           Number of retransmissions.
+ *
+ * @retval  NRF_SUCCESS                         If the operation completed successfully.
+ * @retval  NRF_ERROR_BUSY                      If the function failed because the radio is busy.
+ */
+uint32_t nrf_esb_set_retransmit_count(uint16_t count);
+
+
+/**@brief Function for setting the radio bitrate.
+ *
+ * @param[in]   bitrate                         Radio bitrate.
+ *
+ * @retval  NRF_SUCCESS                         If the operation completed successfully.
+ * @retval  NRF_ERROR_BUSY                      If the function failed because the radio is busy.
+ */
+uint32_t nrf_esb_set_bitrate(nrf_esb_bitrate_t bitrate);
+
+
+/**@brief Function for reusing a packet ID for a specific pipe.
+ *
+ * The ESB protocol uses a 2-bit sequence number (packet ID) to identify
+ * retransmitted packets. By default, the packet ID is incremented for every 
+ * uploaded packet. Use this function to prevent this and send two different 
+ * packets with the same packet ID.
+ *
+ * @param[in]   pipe                            Pipe.
+ *
+ * @retval  NRF_SUCCESS                         If the operation completed successfully.
+ * @retval  NRF_ERROR_BUSY                      If the function failed because the radio is busy.
+ */
+uint32_t nrf_esb_reuse_pid(uint8_t pipe);
+
+/** @} */
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // NRF_ESB
\ No newline at end of file
diff -r a01a54c0dc90 -r 66f95e364222 nrf_esb_error_codes.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nrf_esb_error_codes.h	Thu Feb 04 10:36:44 2021 +0000
@@ -0,0 +1,56 @@
+/**
+ * Copyright (c) 2016 - 2018, Nordic Semiconductor ASA
+ * 
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form, except as embedded into a Nordic
+ *    Semiconductor ASA integrated circuit in a product or a software update for
+ *    such product, must reproduce the above copyright notice, this list of
+ *    conditions and the following disclaimer in the documentation and/or other
+ *    materials provided with the distribution.
+ * 
+ * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
+ *    contributors may be used to endorse or promote products derived from this
+ *    software without specific prior written permission.
+ * 
+ * 4. This software, with or without modification, must only be used with a
+ *    Nordic Semiconductor ASA integrated circuit.
+ * 
+ * 5. Any software provided in binary form under this license must not be reverse
+ *    engineered, decompiled, modified and/or disassembled.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
+ * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
+ * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ */
+#ifndef __NRF_ESB_ERROR_CODES_H__
+#define __NRF_ESB_ERROR_CODES_H__
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define     NRF_ERROR_BUFFER_EMPTY              (0x0100)
+
+#define     NRF_ESB_ERROR_NOT_IN_RX_MODE        (0x0101)
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
\ No newline at end of file
diff -r a01a54c0dc90 -r 66f95e364222 nrf_esb_resources.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/nrf_esb_resources.h	Thu Feb 04 10:36:44 2021 +0000
@@ -0,0 +1,72 @@
+/**
+ * Copyright (c) 2016 - 2018, Nordic Semiconductor ASA
+ * 
+ * All rights reserved.
+ * 
+ * Redistribution and use in source and binary forms, with or without modification,
+ * are permitted provided that the following conditions are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ * 
+ * 2. Redistributions in binary form, except as embedded into a Nordic
+ *    Semiconductor ASA integrated circuit in a product or a software update for
+ *    such product, must reproduce the above copyright notice, this list of
+ *    conditions and the following disclaimer in the documentation and/or other
+ *    materials provided with the distribution.
+ * 
+ * 3. Neither the name of Nordic Semiconductor ASA nor the names of its
+ *    contributors may be used to endorse or promote products derived from this
+ *    software without specific prior written permission.
+ * 
+ * 4. This software, with or without modification, must only be used with a
+ *    Nordic Semiconductor ASA integrated circuit.
+ * 
+ * 5. Any software provided in binary form under this license must not be reverse
+ *    engineered, decompiled, modified and/or disassembled.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY NORDIC SEMICONDUCTOR ASA "AS IS" AND ANY EXPRESS
+ * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY, NONINFRINGEMENT, AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL NORDIC SEMICONDUCTOR ASA OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
+ * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * 
+ */
+#ifndef NRF_ESB_RESOURCES_H__
+#define NRF_ESB_RESOURCES_H__
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * @defgroup nrf_esb_resources ESB resources
+ * @{
+ * @ingroup nrf_esb
+ */
+
+#ifndef ESB_ALTERNATIVE_RESOURCES
+    #define ESB_PPI_CHANNELS_USED    0x00000007uL /**< PPI channels used by ESB (not available to the application). */
+    #define ESB_TIMERS_USED          0x00000004uL /**< Timers used by ESB. */
+    #define ESB_SWI_USED             0x00000001uL /**< Software interrupts used by ESB. */
+#else
+    #define ESB_PPI_CHANNELS_USED    0x00000700uL /**< PPI channels used by ESB (not available to the application). */
+    #define ESB_TIMERS_USED          0x00000001uL /**< Timers used by ESB. */
+    #define ESB_SWI_USED             0x00000002uL /**< Software interrupts used by ESB. */
+#endif
+
+/** @} */
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* NRF_ESB_RESOURCES_H__ */
\ No newline at end of file