void i2c_init(i2c_t *obj, PinName sda, PinName scl)
{
ret_code_t ret;
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) {
ret = nrf_drv_common_per_res_acquire(m_twi_instances[i],
m_twi_irq_handlers[i]);
if (ret != NRF_SUCCESS) {
continue; /* the hw resource is busy - test another one */
}
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
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");
}
static void twi_event_handler(nrf_drv_twi_evt_t const *event, void *context)
{
twi_info_t * twi_info = TWI_INFO((i2c_t *)context);
twi_info->transfer_finished = true;
#if DEVICE_I2C_ASYNCH
switch (event->type) {
case NRF_DRV_TWI_EVT_DONE:
twi_info->events |= I2C_EVENT_TRANSFER_COMPLETE;
break;
case NRF_DRV_TWI_EVT_ADDRESS_NACK:
twi_info->events |= I2C_EVENT_ERROR_NO_SLAVE;
break;
case NRF_DRV_TWI_EVT_DATA_NACK:
twi_info->events |= I2C_EVENT_ERROR;
break;
}
if (twi_info->handler) {
twi_info->handler();
}
#endif // 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);
}
void i2c_reset(i2c_t *obj)
{
twi_info_t *twi_info = TWI_INFO(obj);
nrf_drv_twi_t const *twi = &m_twi_instances[TWI_IDX(obj)];
nrf_drv_twi_uninit(twi);
nrf_drv_twi_init(twi, &twi_info->config, twi_event_handler, obj);
nrf_drv_twi_enable(twi);
}
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;
}
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].config.sda == (uint32_t)sda &&
m_twi_info[i].config.scl == (uint32_t)scl) {
TWI_IDX(obj) = i;
TWI_INFO(obj)->config.frequency = NRF_TWI_FREQ_100K;
i2c_reset(obj);
return;
}
}
nrf_drv_twi_config_t const config = {
.scl = scl,
.sda = sda,
.frequency = NRF_TWI_FREQ_100K,
.interrupt_priority = APP_IRQ_PRIORITY_LOW,
};
for (i = 0; i < TWI_COUNT; ++i) {
if (!m_twi_info[i].initialized) {
nrf_drv_twi_t const *twi = &m_twi_instances[i];
ret_code_t ret_code =
nrf_drv_twi_init(twi, &config, twi_event_handler, obj);
if (ret_code == NRF_SUCCESS) {
TWI_IDX(obj) = i;
TWI_INFO(obj)->initialized = true;
TWI_INFO(obj)->config = config;
nrf_drv_twi_enable(twi);
return;
}
}
}
// No available peripheral
error("No available I2C peripheral\r\n");
}
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);
}
int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop)
{
twi_info_t *twi_info = TWI_INFO(obj);
nrf_drv_twi_t const *twi = &m_twi_instances[TWI_IDX(obj)];
twi_info->transfer_finished = false;
ret_code_t ret_code = nrf_drv_twi_tx(twi, twi_address(address),
(uint8_t const *)data, length, (stop == 0));
if (ret_code != NRF_SUCCESS) {
return 0;
}
while (!twi_info->transfer_finished) {}
return nrf_drv_twi_data_count_get(twi);
}
void i2c_frequency(i2c_t *obj, int hz)
{
twi_info_t *twi_info = TWI_INFO(obj);
nrf_drv_twi_t const *twi = &m_twi_instances[TWI_IDX(obj)];
if (hz < 250000) {
twi_info->config.frequency = NRF_TWI_FREQ_100K;
} else if (hz < 400000) {
twi_info->config.frequency = NRF_TWI_FREQ_250K;
} else {
twi_info->config.frequency = NRF_TWI_FREQ_400K;
}
nrf_twi_frequency_set(twi->reg.p_twi, twi_info->config.frequency);
}
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)stop;
(void)hint;
if (i2c_active(obj)) {
return;
}
if ((tx_length == 0) && (rx_length == 0)) {
return;
}
twi_info_t *twi_info = TWI_INFO(obj);
twi_info->events = 0;
twi_info->handler = (void (*)(void))handler;
twi_info->event_mask = event;
uint8_t twi_addr = twi_address(address);
nrf_drv_twi_t const *twi = &m_twi_instances[TWI_IDX(obj)];
if ((tx_length > 0) && (rx_length == 0)) {
nrf_drv_twi_xfer_desc_t const xfer =
NRF_DRV_TWI_XFER_DESC_TX(twi_addr, (uint8_t *)tx, tx_length);
nrf_drv_twi_xfer(twi, &xfer,
stop ? 0 : NRF_DRV_TWI_FLAG_TX_NO_STOP);
}
else if ((tx_length == 0) && (rx_length > 0)) {
nrf_drv_twi_xfer_desc_t const xfer =
NRF_DRV_TWI_XFER_DESC_RX(twi_addr, rx, rx_length);
nrf_drv_twi_xfer(twi, &xfer, 0);
}
else if ((tx_length > 0) && (rx_length > 0)) {
nrf_drv_twi_xfer_desc_t const xfer =
NRF_DRV_TWI_XFER_DESC_TXRX(twi_addr,
(uint8_t *)tx, tx_length, rx, rx_length);
nrf_drv_twi_xfer(twi, &xfer, 0);
}
}
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);
}
}
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;
}
uint8_t i2c_active(i2c_t *obj)
{
twi_info_t *twi_info = TWI_INFO(obj);
return twi_info->active;
}
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);
}
int i2c_write(i2c_t *obj, int address, const char *data, int length, int stop)
{
twi_info_t *twi_info = TWI_INFO(obj);
bool timeout = false;
uint32_t t0, t1;
#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);
}
t0 = ticker_read(get_us_ticker_data());
do {
if (nrf_twi_event_check(twi, event)) {
break;
}
t1 = ticker_read(get_us_ticker_data());
timeout = (t1 - t0) >= I2C_TIMEOUT_VALUE_US;
} while (!timeout);
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 (timeout ? I2C_ERROR_BUS_BUSY : 0);
}
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;
}
