MacroRat
Mouse code for the MacroRat
Diff: mbed-dev/targets/TARGET_NORDIC/TARGET_NRF5_SDK13/i2c_api.c
- Revision:
- 18:6a4db94011d3
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-dev/targets/TARGET_NORDIC/TARGET_NRF5_SDK13/i2c_api.c Sun May 14 23:18:57 2017 +0000
@@ -0,0 +1,784 @@
+/*
+ * Copyright (c) 2017 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 or object form under this license must not be reverse
+ * engineered, decompiled, modified and/or disassembled.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER 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 "i2c_api.h"
+
+#if DEVICE_I2C
+
+#include "mbed_assert.h"
+#include "mbed_error.h"
+#include "nrf_twi.h"
+#include "nrf_drv_common.h"
+#include "sdk_config.h"
+#include "app_util_platform.h"
+#include "nrf_gpio.h"
+#include "nrf_delay.h"
+
+// An arbitrary value used as the counter in loops waiting for given event
+// (e.g. STOPPED), needed to avoid infinite loops (and not involve any timers
+// or tickers).
+#define TIMEOUT_VALUE 1000
+
+#if DEVICE_I2C_ASYNCH
+ #define TWI_IDX(obj) ((obj)->i2c.twi_idx)
+#else
+ #define TWI_IDX(obj) ((obj)->twi_idx)
+#endif
+#define TWI_INFO(obj) (&m_twi_info[TWI_IDX(obj)])
+
+#define TWI0_INSTANCE_INDEX 0
+#define TWI1_INSTANCE_INDEX TWI0_INSTANCE_INDEX+TWI0_ENABLED
+
+typedef struct {
+ bool initialized;
+ uint32_t pselsda;
+ uint32_t pselscl;
+ nrf_twi_frequency_t frequency;
+ bool start_twi;
+
+#if DEVICE_I2C_ASYNCH
+ volatile bool active;
+ uint8_t const *tx;
+ size_t tx_length;
+ uint8_t *rx;
+ size_t rx_length;
+ bool stop;
+
+ volatile uint32_t events;
+ void (*handler)(void);
+ uint32_t evt_mask;
+#endif // DEVICE_I2C_ASYNCH
+} twi_info_t;
+static twi_info_t m_twi_info[TWI_COUNT];
+
+static NRF_TWI_Type * const m_twi_instances[TWI_COUNT] = {
+#if TWI0_ENABLED
+ NRF_TWI0,
+#endif
+#if TWI1_ENABLED
+ NRF_TWI1,
+#endif
+};
+
+void SPI0_TWI0_IRQHandler(void);
+void SPI1_TWI1_IRQHandler(void);
+
+static const peripheral_handler_desc_t twi_handlers[TWI_COUNT] =
+{
+#if TWI0_ENABLED
+ {
+ SPI0_TWI0_IRQn,
+ (uint32_t) SPI0_TWI0_IRQHandler
+ },
+#endif
+#if TWI1_ENABLED
+ {
+ SPI1_TWI1_IRQn,
+ (uint32_t) SPI1_TWI1_IRQHandler
+ }
+#endif
+};
+#ifdef NRF51
+ #define TWI_IRQ_PRIORITY APP_IRQ_PRIORITY_LOW
+#elif defined(NRF52) || defined(NRF52840_XXAA)
+ #define TWI_IRQ_PRIORITY APP_IRQ_PRIORITY_LOWEST
+#endif
+
+
+#if DEVICE_I2C_ASYNCH
+static void start_asynch_rx(twi_info_t *twi_info, NRF_TWI_Type *twi)
+{
+ if (twi_info->rx_length == 1 && twi_info->stop)
+ {
+ nrf_twi_shorts_set(twi, NRF_TWI_SHORT_BB_STOP_MASK);
+ }
+ else
+ {
+ nrf_twi_shorts_set(twi, NRF_TWI_SHORT_BB_SUSPEND_MASK);
+ }
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_STARTRX);
+}
+
+static void twi_irq_handler(uint8_t instance_idx)
+{
+ twi_info_t *twi_info = &m_twi_info[instance_idx];
+
+ NRF_TWI_Type *twi = m_twi_instances[instance_idx];
+ if (nrf_twi_event_check(twi, NRF_TWI_EVENT_ERROR))
+ {
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_ERROR);
+
+ // In case of an error, force STOP.
+ // The current transfer may be suspended (if it is RX), so it must be
+ // resumed before the STOP task is triggered.
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_RESUME);
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_STOP);
+
+ uint32_t errorsrc = nrf_twi_errorsrc_get_and_clear(twi);
+ twi_info->events |= I2C_EVENT_ERROR;
+ if (errorsrc & NRF_TWI_ERROR_ADDRESS_NACK)
+ {
+ twi_info->events |= I2C_EVENT_ERROR_NO_SLAVE;
+ }
+ if (errorsrc & NRF_TWI_ERROR_DATA_NACK)
+ {
+ twi_info->events |= I2C_EVENT_TRANSFER_EARLY_NACK;
+ }
+ }
+
+ bool finished = false;
+
+ if (nrf_twi_event_check(twi, NRF_TWI_EVENT_TXDSENT))
+ {
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_TXDSENT);
+
+ MBED_ASSERT(twi_info->tx_length > 0);
+ --(twi_info->tx_length);
+ // Send next byte if there is still something to be sent.
+ if (twi_info->tx_length > 0)
+ {
+ nrf_twi_txd_set(twi, *(twi_info->tx));
+ ++(twi_info->tx);
+ // It TX is done, start RX if requested.
+ }
+ else if (twi_info->rx_length > 0)
+ {
+ start_asynch_rx(twi_info, twi);
+ // If there is nothing more to do, finalize the transfer.
+ }
+ else
+ {
+ if (twi_info->stop)
+ {
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_STOP);
+ }
+ else
+ {
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_SUSPEND);
+ finished = true;
+ }
+ twi_info->events |= I2C_EVENT_TRANSFER_COMPLETE;
+ }
+ }
+
+ if (nrf_twi_event_check(twi, NRF_TWI_EVENT_RXDREADY))
+ {
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_RXDREADY);
+
+ MBED_ASSERT(twi_info->rx_length > 0);
+ *(twi_info->rx) = nrf_twi_rxd_get(twi);
+ ++(twi_info->rx);
+ --(twi_info->rx_length);
+
+ if (twi_info->rx_length > 0)
+ {
+ // If more bytes should be received, resume the transfer
+ // (in case the stop condition should be generated after the next
+ // byte, change the shortcuts configuration first).
+ if (twi_info->rx_length == 1 && twi_info->stop)
+ {
+ nrf_twi_shorts_set(twi, NRF_TWI_SHORT_BB_STOP_MASK);
+ }
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_RESUME);
+ }
+ else
+ {
+ // If all requested bytes were received, finalize the transfer.
+ finished = true;
+ twi_info->events |= I2C_EVENT_TRANSFER_COMPLETE;
+ }
+ }
+
+ if (finished ||
+ nrf_twi_event_check(twi, NRF_TWI_EVENT_STOPPED) ||
+ (nrf_twi_int_enable_check(twi, NRF_TWI_INT_SUSPENDED_MASK) &&
+ nrf_twi_event_check(twi, NRF_TWI_EVENT_SUSPENDED)))
+ {
+ // There is no need to clear the STOPPED and SUSPENDED events here,
+ // they will no longer generate the interrupt - see below.
+
+ nrf_twi_shorts_set(twi, 0);
+ // Disable all interrupt sources.
+ nrf_twi_int_disable(twi, UINT32_MAX);
+ twi_info->active = false;
+
+ if (twi_info->handler)
+ {
+ twi_info->handler();
+ }
+ }
+}
+
+#if TWI0_ENABLED
+static void irq_handler_twi0(void)
+{
+ twi_irq_handler(TWI0_INSTANCE_INDEX);
+}
+#endif
+#if TWI1_ENABLED
+static void irq_handler_twi1(void)
+{
+ twi_irq_handler(TWI1_INSTANCE_INDEX);
+}
+#endif
+static nrf_drv_irq_handler_t const m_twi_irq_handlers[TWI_COUNT] =
+{
+#if TWI0_ENABLED
+ irq_handler_twi0,
+#endif
+#if TWI1_ENABLED
+ irq_handler_twi1,
+#endif
+};
+#endif // DEVICE_I2C_ASYNCH
+
+
+static void configure_twi_pin(uint32_t pin, nrf_gpio_pin_dir_t dir)
+{
+ nrf_gpio_cfg(pin,
+ dir,
+ NRF_GPIO_PIN_INPUT_CONNECT,
+ NRF_GPIO_PIN_PULLUP,
+ NRF_GPIO_PIN_S0D1,
+ NRF_GPIO_PIN_NOSENSE);
+}
+
+static void twi_clear_bus(twi_info_t *twi_info)
+{
+ // Try to set SDA high, and check if no slave tries to drive it low.
+ nrf_gpio_pin_set(twi_info->pselsda);
+ configure_twi_pin(twi_info->pselsda, NRF_GPIO_PIN_DIR_OUTPUT);
+ // In case SDA is low, make up to 9 cycles on SCL line to help the slave
+ // that pulls SDA low release it.
+ if (!nrf_gpio_pin_read(twi_info->pselsda))
+ {
+ nrf_gpio_pin_set(twi_info->pselscl);
+ configure_twi_pin(twi_info->pselscl, NRF_GPIO_PIN_DIR_OUTPUT);
+ nrf_delay_us(4);
+
+ for (int i = 0; i < 9; i++)
+ {
+ if (nrf_gpio_pin_read(twi_info->pselsda))
+ {
+ break;
+ }
+ nrf_gpio_pin_clear(twi_info->pselscl);
+ nrf_delay_us(4);
+ nrf_gpio_pin_set(twi_info->pselscl);
+ nrf_delay_us(4);
+ }
+
+ // Finally, generate STOP condition to put the bus into initial state.
+ nrf_gpio_pin_clear(twi_info->pselsda);
+ nrf_delay_us(4);
+ nrf_gpio_pin_set(twi_info->pselsda);
+ }
+}
+
+void i2c_init(i2c_t *obj, PinName sda, PinName scl)
+{
+ int i;
+
+ for (i = 0; i < TWI_COUNT; ++i)
+ {
+ if (m_twi_info[i].initialized &&
+ m_twi_info[i].pselsda == (uint32_t)sda &&
+ m_twi_info[i].pselscl == (uint32_t)scl)
+ {
+ TWI_IDX(obj) = i;
+ TWI_INFO(obj)->frequency = NRF_TWI_FREQ_100K;
+ i2c_reset(obj);
+ return;
+ }
+ }
+
+ for (i = 0; i < TWI_COUNT; ++i)
+ {
+ if (!m_twi_info[i].initialized)
+ {
+ TWI_IDX(obj) = i;
+
+ twi_info_t *twi_info = TWI_INFO(obj);
+ twi_info->initialized = true;
+ twi_info->pselsda = (uint32_t)sda;
+ twi_info->pselscl = (uint32_t)scl;
+ twi_info->frequency = NRF_TWI_FREQ_100K;
+ twi_info->start_twi = false;
+#if DEVICE_I2C_ASYNCH
+ twi_info->active = false;
+#endif
+
+ twi_clear_bus(twi_info);
+
+ configure_twi_pin(twi_info->pselsda, NRF_GPIO_PIN_DIR_INPUT);
+ configure_twi_pin(twi_info->pselscl, NRF_GPIO_PIN_DIR_INPUT);
+
+ i2c_reset(obj);
+
+#if DEVICE_I2C_ASYNCH
+ nrf_drv_common_per_res_acquire(m_twi_instances[i],
+ m_twi_irq_handlers[i]);
+ NVIC_SetVector(twi_handlers[i].IRQn, twi_handlers[i].vector);
+ nrf_drv_common_irq_enable(twi_handlers[i].IRQn, TWI_IRQ_PRIORITY);
+#endif
+
+ return;
+ }
+ }
+
+ error("No available I2C peripheral\r\n");
+}
+
+void i2c_reset(i2c_t *obj)
+{
+ twi_info_t *twi_info = TWI_INFO(obj);
+ NRF_TWI_Type *twi = m_twi_instances[TWI_IDX(obj)];
+
+ nrf_twi_disable(twi);
+ nrf_twi_pins_set(twi, twi_info->pselscl, twi_info->pselsda);
+ nrf_twi_frequency_set(twi, twi_info->frequency);
+ nrf_twi_enable(twi);
+}
+
+int i2c_start(i2c_t *obj)
+{
+ twi_info_t *twi_info = TWI_INFO(obj);
+#if DEVICE_I2C_ASYNCH
+ if (twi_info->active)
+ {
+ return I2C_ERROR_BUS_BUSY;
+ }
+#endif
+ twi_info->start_twi = true;
+
+ return 0;
+}
+
+int i2c_stop(i2c_t *obj)
+{
+ NRF_TWI_Type *twi = m_twi_instances[TWI_IDX(obj)];
+
+ // The current transfer may be suspended (if it is RX), so it must be
+ // resumed before the STOP task is triggered.
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_RESUME);
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_STOP);
+ uint32_t remaining_time = TIMEOUT_VALUE;
+
+ do
+ {
+ if (nrf_twi_event_check(twi, NRF_TWI_EVENT_STOPPED))
+ {
+ return 0;
+ }
+ }
+ while (--remaining_time);
+
+ return 1;
+}
+
+void i2c_frequency(i2c_t *obj, int hz)
+{
+ twi_info_t *twi_info = TWI_INFO(obj);
+ NRF_TWI_Type *twi = m_twi_instances[TWI_IDX(obj)];
+
+ if (hz < 250000)
+ {
+ twi_info->frequency = NRF_TWI_FREQ_100K;
+ }
+ else if (hz < 400000)
+ {
+ twi_info->frequency = NRF_TWI_FREQ_250K;
+ }
+ else
+ {
+ twi_info->frequency = NRF_TWI_FREQ_400K;
+ }
+ nrf_twi_frequency_set(twi, twi_info->frequency);
+}
+
+static uint8_t twi_address(int i2c_address)
+{
+ // The TWI peripheral requires 7-bit slave address (without R/W bit).
+ return (i2c_address >> 1);
+}
+
+static void start_twi_read(NRF_TWI_Type *twi, int address)
+{
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_STOPPED);
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_RXDREADY);
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_ERROR);
+ (void)nrf_twi_errorsrc_get_and_clear(twi);
+
+ nrf_twi_shorts_set(twi, NRF_TWI_SHORT_BB_SUSPEND_MASK);
+
+ nrf_twi_address_set(twi, twi_address(address));
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_RESUME);
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_STARTRX);
+}
+
+int i2c_read(i2c_t *obj, int address, char *data, int length, int stop)
+{
+ // Zero-length RX transfers are not supported. Such transfers cannot
+ // be easily achieved with TWI peripheral (some dirty tricks would be
+ // required for this), and they are actually useless (TX can be used
+ // to check if the address is acknowledged by a slave).
+ MBED_ASSERT(length > 0);
+
+ twi_info_t *twi_info = TWI_INFO(obj);
+#if DEVICE_I2C_ASYNCH
+ if (twi_info->active)
+ {
+ return I2C_ERROR_BUS_BUSY;
+ }
+#endif
+ twi_info->start_twi = false;
+
+ NRF_TWI_Type *twi = m_twi_instances[TWI_IDX(obj)];
+ start_twi_read(twi, address);
+
+ int result = length;
+
+ while (length > 0)
+ {
+ int byte_read_result = i2c_byte_read(obj, (stop && length == 1));
+ if (byte_read_result < 0)
+ {
+ // When an error occurs, return the number of bytes that have been
+ // received successfully.
+ result -= length;
+ // Force STOP condition.
+ stop = 1;
+ break;
+ }
+ *data++ = (uint8_t)byte_read_result;
+ --length;
+ }
+
+ if (stop)
+ {
+ (void)i2c_stop(obj);
+ }
+
+ return result;
+}
+
+static uint8_t twi_byte_write(NRF_TWI_Type *twi, uint8_t data)
+{
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_TXDSENT);
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_ERROR);
+
+ nrf_twi_txd_set(twi, data);
+ uint32_t remaining_time = TIMEOUT_VALUE;
+
+ do
+ {
+ if (nrf_twi_event_check(twi, NRF_TWI_EVENT_TXDSENT))
+ {
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_TXDSENT);
+ return 1; // ACK received
+ }
+ if (nrf_twi_event_check(twi, NRF_TWI_EVENT_ERROR))
+ {
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_ERROR);
+ return 0; // some error occurred
+ }
+ }
+ while (--remaining_time);
+
+ return 2; // timeout;
+}
+
+static void start_twi_write(NRF_TWI_Type *twi, int address)
+{
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_STOPPED);
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_TXDSENT);
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_ERROR);
+ (void)nrf_twi_errorsrc_get_and_clear(twi);
+
+ nrf_twi_shorts_set(twi, 0);
+
+ nrf_twi_address_set(twi, twi_address(address));
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_RESUME);
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_STARTTX);
+}
+
+int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop)
+{
+ twi_info_t *twi_info = TWI_INFO(obj);
+#if DEVICE_I2C_ASYNCH
+ if (twi_info->active)
+ {
+ return I2C_ERROR_BUS_BUSY;
+ }
+#endif
+ twi_info->start_twi = false;
+
+ NRF_TWI_Type *twi = m_twi_instances[TWI_IDX(obj)];
+ start_twi_write(twi, address);
+
+ // Special case - transaction with no data.
+ // It can be used to check if a slave acknowledges the address.
+ if (length == 0)
+ {
+ nrf_twi_event_t event;
+ if (stop)
+ {
+ event = NRF_TWI_EVENT_STOPPED;
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_STOP);
+ }
+ else
+ {
+ event = NRF_TWI_EVENT_SUSPENDED;
+ nrf_twi_event_clear(twi, event);
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_SUSPEND);
+ }
+ uint32_t remaining_time = TIMEOUT_VALUE;
+
+ do
+ {
+ if (nrf_twi_event_check(twi, event))
+ {
+ break;
+ }
+ }
+ while (--remaining_time);
+
+ uint32_t errorsrc = nrf_twi_errorsrc_get_and_clear(twi);
+ if (errorsrc & NRF_TWI_ERROR_ADDRESS_NACK)
+ {
+ if (!stop)
+ {
+ i2c_stop(obj);
+ }
+ return I2C_ERROR_NO_SLAVE;
+ }
+
+ return (remaining_time ? 0 : I2C_ERROR_BUS_BUSY);
+ }
+
+ int result = length;
+
+ do
+ {
+ uint8_t byte_write_result = twi_byte_write(twi, (uint8_t)*data++);
+ if (byte_write_result != 1)
+ {
+ if (byte_write_result == 0)
+ {
+ // Check what kind of error has been signaled by TWI.
+ uint32_t errorsrc = nrf_twi_errorsrc_get_and_clear(twi);
+ if (errorsrc & NRF_TWI_ERROR_ADDRESS_NACK)
+ {
+ result = I2C_ERROR_NO_SLAVE;
+ }
+ else
+ {
+ // Some other error - return the number of bytes that
+ // have been sent successfully.
+ result -= length;
+ }
+ }
+ else
+ {
+ result = I2C_ERROR_BUS_BUSY;
+ }
+ // Force STOP condition.
+ stop = 1;
+ break;
+ }
+ --length;
+ }
+ while (length > 0);
+
+ if (stop)
+ {
+ (void)i2c_stop(obj);
+ }
+
+ return result;
+}
+
+int i2c_byte_read(i2c_t *obj, int last)
+{
+ NRF_TWI_Type *twi = m_twi_instances[TWI_IDX(obj)];
+
+ if (last)
+ {
+ nrf_twi_shorts_set(twi, NRF_TWI_SHORT_BB_STOP_MASK);
+ }
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_RESUME);
+
+ uint32_t remaining_time = TIMEOUT_VALUE;
+
+ do
+ {
+ if (nrf_twi_event_check(twi, NRF_TWI_EVENT_RXDREADY))
+ {
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_RXDREADY);
+ return nrf_twi_rxd_get(twi);
+ }
+ if (nrf_twi_event_check(twi, NRF_TWI_EVENT_ERROR))
+ {
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_ERROR);
+ return I2C_ERROR_NO_SLAVE;
+ }
+ }
+ while (--remaining_time);
+
+ return I2C_ERROR_BUS_BUSY;
+}
+
+int i2c_byte_write(i2c_t *obj, int data)
+{
+ NRF_TWI_Type *twi = m_twi_instances[TWI_IDX(obj)];
+ twi_info_t *twi_info = TWI_INFO(obj);
+ if (twi_info->start_twi)
+ {
+ twi_info->start_twi = false;
+
+ if (data & 1)
+ {
+ start_twi_read(twi, data);
+ }
+ else
+ {
+ start_twi_write(twi, data);
+ }
+ return 1;
+ }
+ else
+ {
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_RESUME);
+ // 0 - TWI signaled error (NAK is the only possibility here)
+ // 1 - ACK received
+ // 2 - timeout (clock stretched for too long?)
+ return twi_byte_write(twi, (uint8_t)data);
+ }
+}
+
+
+#if DEVICE_I2C_ASYNCH
+void i2c_transfer_asynch(i2c_t *obj, const void *tx, size_t tx_length,
+ void *rx, size_t rx_length, uint32_t address,
+ uint32_t stop, uint32_t handler,
+ uint32_t event, DMAUsage hint)
+{
+ (void)hint;
+
+ twi_info_t *twi_info = TWI_INFO(obj);
+ if (twi_info->active)
+ {
+ return;
+ }
+ twi_info->active = true;
+ twi_info->events = 0;
+ twi_info->handler = (void (*)(void))handler;
+ twi_info->evt_mask = event;
+ twi_info->tx_length = tx_length;
+ twi_info->tx = tx;
+ twi_info->rx_length = rx_length;
+ twi_info->rx = rx;
+ twi_info->stop = stop;
+
+ NRF_TWI_Type *twi = m_twi_instances[TWI_IDX(obj)];
+
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_TXDSENT);
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_RXDREADY);
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_STOPPED);
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_SUSPENDED);
+ nrf_twi_event_clear(twi, NRF_TWI_EVENT_ERROR);
+ (void)nrf_twi_errorsrc_get_and_clear(twi);
+
+ nrf_twi_address_set(twi, twi_address(address));
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_RESUME);
+ // TX only, or TX + RX (after a repeated start).
+ if (tx_length > 0)
+ {
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_STARTTX);
+ nrf_twi_txd_set(twi, *(twi_info->tx));
+ ++(twi_info->tx);
+ // RX only.
+ }
+ else if (rx_length > 0)
+ {
+ start_asynch_rx(twi_info, twi);
+ // Both 'tx_length' and 'rx_length' are 0 - this case may be used
+ // to test if the slave is presentand ready for transfer (by just
+ // sending the address and checking if it is acknowledged).
+ }
+ else
+ {
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_STARTTX);
+ if (stop)
+ {
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_STOP);
+ }
+ else
+ {
+ nrf_twi_task_trigger(twi, NRF_TWI_TASK_SUSPEND);
+ nrf_twi_int_enable(twi, NRF_TWI_INT_SUSPENDED_MASK);
+ }
+ twi_info->events |= I2C_EVENT_TRANSFER_COMPLETE;
+ }
+
+ nrf_twi_int_enable(twi, NRF_TWI_INT_TXDSENT_MASK |
+ NRF_TWI_INT_RXDREADY_MASK |
+ NRF_TWI_INT_STOPPED_MASK |
+ NRF_TWI_INT_ERROR_MASK);
+}
+
+uint32_t i2c_irq_handler_asynch(i2c_t *obj)
+{
+ twi_info_t *twi_info = TWI_INFO(obj);
+ return (twi_info->events & twi_info->evt_mask);
+}
+
+uint8_t i2c_active(i2c_t *obj)
+{
+ twi_info_t *twi_info = TWI_INFO(obj);
+ return twi_info->active;
+}
+
+void i2c_abort_asynch(i2c_t *obj)
+{
+ i2c_reset(obj);
+}
+#endif // DEVICE_I2C_ASYNCH
+
+#endif // DEVICE_I2C