Diff: targets/TARGET_NORDIC/TARGET_MCU_NRF51822/twi_master.c

Revision:

149:156823d33999

Parent:

144:ef7eb2e8f9f7

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NORDIC/TARGET_MCU_NRF51822/twi_master.c	Fri Oct 28 11:17:30 2016 +0100
@@ -0,0 +1,304 @@
+/* Copyright (c) 2009 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 "twi_master.h"
+#include "twi_config.h"
+#include <stdbool.h>
+#include <stdint.h>
+#include "nrf.h"
+#include "nrf_delay.h"
+
+/* Max cycles approximately to wait on RXDREADY and TXDREADY event,
+ * This is optimized way instead of using timers, this is not power aware. */
+#define MAX_TIMEOUT_LOOPS (20000UL) /**< MAX while loops to wait for RXD/TXD event */
+
+static bool twi_master_write(uint8_t * data, uint8_t data_length, bool issue_stop_condition, NRF_TWI_Type* twi)
+{
+    uint32_t timeout = MAX_TIMEOUT_LOOPS; /* max loops to wait for EVENTS_TXDSENT event*/
+
+    if (data_length == 0)
+    {
+        /* Return false for requesting data of size 0 */
+        return false;
+    }
+
+    twi->TXD           = *data++;
+    twi->TASKS_STARTTX = 1;
+
+    /** @snippet [TWI HW master write] */
+    while (true)
+    {
+        while (twi->EVENTS_TXDSENT == 0 && twi->EVENTS_ERROR == 0 && (--timeout))
+        {
+            // Do nothing.
+        }
+
+        if (timeout == 0 || NRF_TWI1->EVENTS_ERROR != 0)
+        {
+            // Recover the peripheral as indicated by PAN 56: "TWI: TWI module lock-up." found at
+            // Product Anomaly Notification document found at 
+            // https://www.nordicsemi.com/eng/Products/Bluetooth-R-low-energy/nRF51822/#Downloads
+            twi->EVENTS_ERROR = 0;
+            twi->ENABLE       = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
+            twi->POWER        = 0;
+            nrf_delay_us(5);
+            twi->POWER        = 1;
+            twi->ENABLE       = TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos;
+
+            (void)twi_master_init_and_clear(twi);
+
+            return false;
+        }
+        twi->EVENTS_TXDSENT = 0;
+        if (--data_length == 0)
+        {
+            break;
+        }
+
+        twi->TXD = *data++;
+    }
+    /** @snippet [TWI HW master write] */
+
+    if (issue_stop_condition)
+    {
+        twi->EVENTS_STOPPED = 0;
+        twi->TASKS_STOP     = 1;
+        /* Wait until stop sequence is sent */ 
+        while(twi->EVENTS_STOPPED == 0)
+        {
+            // Do nothing.
+        }
+    }
+    return true;
+}
+
+
+/** @brief Function for read by twi_master. 
+ */
+static bool twi_master_read(uint8_t * data, uint8_t data_length, bool issue_stop_condition, NRF_TWI_Type* twi)
+{
+    uint32_t timeout = MAX_TIMEOUT_LOOPS; /* max loops to wait for RXDREADY event*/
+
+    if (data_length == 0)
+    {
+        /* Return false for requesting data of size 0 */
+        return false;
+    }
+    else if (data_length == 1)
+    {
+        NRF_PPI->CH[0].TEP = (uint32_t)&twi->TASKS_STOP;
+    }
+    else
+    {
+        NRF_PPI->CH[0].TEP = (uint32_t)&twi->TASKS_SUSPEND;
+    }
+
+    NRF_PPI->CHENSET          = PPI_CHENSET_CH0_Msk;
+    twi->EVENTS_RXDREADY = 0;
+    twi->TASKS_STARTRX   = 1;
+
+    /** @snippet [TWI HW master read] */
+    while (true)
+    {
+        while (twi->EVENTS_RXDREADY == 0 && NRF_TWI1->EVENTS_ERROR == 0 && (--timeout))
+        {
+            // Do nothing.
+        }
+        twi->EVENTS_RXDREADY = 0;
+
+        if (timeout == 0 || twi->EVENTS_ERROR != 0)
+        {
+            // Recover the peripheral as indicated by PAN 56: "TWI: TWI module lock-up." found at
+            // Product Anomaly Notification document found at
+            // https://www.nordicsemi.com/eng/Products/Bluetooth-R-low-energy/nRF51822/#Downloads
+            twi->EVENTS_ERROR = 0;
+            twi->ENABLE       = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
+            twi->POWER        = 0;
+            nrf_delay_us(5);
+            twi->POWER        = 1;
+            twi->ENABLE       = TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos;
+
+            (void)twi_master_init_and_clear(twi);
+
+            return false;
+        }
+
+        *data++ = NRF_TWI1->RXD;
+
+        /* Configure PPI to stop TWI master before we get last BB event */
+        if (--data_length == 1)
+        {
+            NRF_PPI->CH[0].TEP = (uint32_t)&NRF_TWI1->TASKS_STOP;
+        }
+
+        if (data_length == 0)
+        {
+            break;
+        }
+
+        // Recover the peripheral as indicated by PAN 56: "TWI: TWI module lock-up." found at
+        // Product Anomaly Notification document found at
+        // https://www.nordicsemi.com/eng/Products/Bluetooth-R-low-energy/nRF51822/#Downloads
+        nrf_delay_us(20);
+        twi->TASKS_RESUME = 1;
+    }
+    /** @snippet [TWI HW master read] */
+
+    /* Wait until stop sequence is sent */
+    while(twi->EVENTS_STOPPED == 0)
+    {
+        // Do nothing.
+    }
+    twi->EVENTS_STOPPED = 0;
+
+    NRF_PPI->CHENCLR = PPI_CHENCLR_CH0_Msk;
+    return true;
+}
+
+
+/**
+ * @brief Function for detecting stuck slaves (SDA = 0 and SCL = 1) and tries to clear the bus.
+ *
+ * @return
+ * @retval false Bus is stuck.
+ * @retval true Bus is clear.
+ */
+static bool twi_master_clear_bus(NRF_TWI_Type* twi)
+{
+    uint32_t twi_state;
+    bool     bus_clear;
+    uint32_t clk_pin_config;
+    uint32_t data_pin_config;
+
+    // Save and disable TWI hardware so software can take control over the pins.
+    twi_state        = twi->ENABLE;
+    twi->ENABLE = TWI_ENABLE_ENABLE_Disabled << TWI_ENABLE_ENABLE_Pos;
+
+    clk_pin_config = \
+        NRF_GPIO->PIN_CNF[TWI_MASTER_CONFIG_CLOCK_PIN_NUMBER];
+    NRF_GPIO->PIN_CNF[TWI_MASTER_CONFIG_CLOCK_PIN_NUMBER] =      \
+        (GPIO_PIN_CNF_SENSE_Disabled  << GPIO_PIN_CNF_SENSE_Pos) \
+      | (GPIO_PIN_CNF_DRIVE_S0D1    << GPIO_PIN_CNF_DRIVE_Pos)   \
+      | (GPIO_PIN_CNF_PULL_Pullup   << GPIO_PIN_CNF_PULL_Pos)    \
+      | (GPIO_PIN_CNF_INPUT_Connect << GPIO_PIN_CNF_INPUT_Pos)   \
+      | (GPIO_PIN_CNF_DIR_Output    << GPIO_PIN_CNF_DIR_Pos);
+
+    data_pin_config = \
+        NRF_GPIO->PIN_CNF[TWI_MASTER_CONFIG_DATA_PIN_NUMBER];
+    NRF_GPIO->PIN_CNF[TWI_MASTER_CONFIG_DATA_PIN_NUMBER] =       \
+        (GPIO_PIN_CNF_SENSE_Disabled  << GPIO_PIN_CNF_SENSE_Pos) \
+      | (GPIO_PIN_CNF_DRIVE_S0D1    << GPIO_PIN_CNF_DRIVE_Pos)   \
+      | (GPIO_PIN_CNF_PULL_Pullup   << GPIO_PIN_CNF_PULL_Pos)    \
+      | (GPIO_PIN_CNF_INPUT_Connect << GPIO_PIN_CNF_INPUT_Pos)   \
+      | (GPIO_PIN_CNF_DIR_Output    << GPIO_PIN_CNF_DIR_Pos);
+
+    TWI_SDA_HIGH();
+    TWI_SCL_HIGH();
+    TWI_DELAY();
+
+    if ((TWI_SDA_READ() == 1) && (TWI_SCL_READ() == 1))
+    {
+        bus_clear = true;
+    }
+    else
+    {
+        uint_fast8_t i;
+        bus_clear = false;
+
+        // Clock max 18 pulses worst case scenario(9 for master to send the rest of command and 9
+        // for slave to respond) to SCL line and wait for SDA come high.
+        for (i=18; i--;)
+        {
+            TWI_SCL_LOW();
+            TWI_DELAY();
+            TWI_SCL_HIGH();
+            TWI_DELAY();
+
+            if (TWI_SDA_READ() == 1)
+            {
+                bus_clear = true;
+                break;
+            }
+        }
+    }
+
+    NRF_GPIO->PIN_CNF[TWI_MASTER_CONFIG_CLOCK_PIN_NUMBER] = clk_pin_config;
+    NRF_GPIO->PIN_CNF[TWI_MASTER_CONFIG_DATA_PIN_NUMBER]  = data_pin_config;
+
+    twi->ENABLE = twi_state;
+
+    return bus_clear;
+}
+
+
+/** @brief Function for initializing the twi_master.
+ */
+bool twi_master_init_and_clear(NRF_TWI_Type* twi)
+{
+    /* To secure correct signal levels on the pins used by the TWI
+       master when the system is in OFF mode, and when the TWI master is
+       disabled, these pins must be configured in the GPIO peripheral.
+    */
+    NRF_GPIO->PIN_CNF[TWI_MASTER_CONFIG_CLOCK_PIN_NUMBER] =     \
+        (GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos) \
+      | (GPIO_PIN_CNF_DRIVE_S0D1     << GPIO_PIN_CNF_DRIVE_Pos) \
+      | (GPIO_PIN_CNF_PULL_Pullup    << GPIO_PIN_CNF_PULL_Pos)  \
+      | (GPIO_PIN_CNF_INPUT_Connect  << GPIO_PIN_CNF_INPUT_Pos) \
+      | (GPIO_PIN_CNF_DIR_Input      << GPIO_PIN_CNF_DIR_Pos);
+
+    NRF_GPIO->PIN_CNF[TWI_MASTER_CONFIG_DATA_PIN_NUMBER] =      \
+        (GPIO_PIN_CNF_SENSE_Disabled << GPIO_PIN_CNF_SENSE_Pos) \
+      | (GPIO_PIN_CNF_DRIVE_S0D1     << GPIO_PIN_CNF_DRIVE_Pos) \
+      | (GPIO_PIN_CNF_PULL_Pullup    << GPIO_PIN_CNF_PULL_Pos)  \
+      | (GPIO_PIN_CNF_INPUT_Connect  << GPIO_PIN_CNF_INPUT_Pos) \
+      | (GPIO_PIN_CNF_DIR_Input      << GPIO_PIN_CNF_DIR_Pos);
+
+    twi->EVENTS_RXDREADY = 0;
+    twi->EVENTS_TXDSENT  = 0;
+    twi->PSELSCL         = TWI_MASTER_CONFIG_CLOCK_PIN_NUMBER;
+    twi->PSELSDA         = TWI_MASTER_CONFIG_DATA_PIN_NUMBER;
+    twi->FREQUENCY       = TWI_FREQUENCY_FREQUENCY_K100 << TWI_FREQUENCY_FREQUENCY_Pos;
+    NRF_PPI->CH[0].EEP        = (uint32_t)&twi->EVENTS_BB;
+    NRF_PPI->CH[0].TEP        = (uint32_t)&twi->TASKS_SUSPEND;
+    NRF_PPI->CHENCLR          = PPI_CHENCLR_CH0_Msk;
+    twi->ENABLE          = TWI_ENABLE_ENABLE_Enabled << TWI_ENABLE_ENABLE_Pos;
+
+    return twi_master_clear_bus(twi);
+}
+
+
+/** @brief  Function for transfer by twi_master.
+ */
+bool twi_master_transfer(uint8_t   address,
+                         uint8_t * data,
+                         uint8_t   data_length,
+                         bool      issue_stop_condition,
+                         NRF_TWI_Type* twi)
+{
+    bool transfer_succeeded = false;
+    if (data_length > 0 && twi_master_clear_bus(twi))
+    {
+        twi->ADDRESS = (address >> 1);
+
+        if ((address & TWI_READ_BIT))
+        {
+            transfer_succeeded = twi_master_read(data, data_length, issue_stop_condition, twi);
+        }
+        else
+        {
+            transfer_succeeded = twi_master_write(data, data_length, issue_stop_condition, twi);
+        }
+    }
+    return transfer_succeeded;
+}
+
+/*lint --flb "Leave library region" */