int i2c_byte_read(i2c_t *obj, int last)
{
NRF_TWI_Type *twi = m_twi_instances[TWI_IDX(obj)];
uint32_t t0;
if (last) {
nrf_twi_shorts_set(twi, NRF_TWI_SHORT_BB_STOP_MASK);
}
nrf_twi_task_trigger(twi, NRF_TWI_TASK_RESUME);
t0 = ticker_read(get_us_ticker_data());
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 (((uint32_t)ticker_read(get_us_ticker_data()) - t0) < I2C_TIMEOUT_VALUE_US);
return I2C_ERROR_BUS_BUSY;
}
static void rx_done(volatile nrf_drv_twi_t const * const p_instance)
{
volatile transfer_t * p_transfer = &(m_cb[p_instance->instance_id].transfer);
p_transfer->p_data[p_transfer->count] = nrf_twi_rxd_get(p_instance->p_reg);
p_transfer->count++;
if (p_transfer->count < p_transfer->length)
{
rx_prepare(p_instance);
}
}
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();
}
}
}
