With SDK 14.2.0 and S332 softdevice, I'm using UART to control ESP8266 WiFi module with AT commands and I'd like to replace app_uart (+FIFO) with nrf_serial, in order to get better control over UART communication. My UART connection uses 115200 baudrate with flow control enabled, and it worked fine with app_uart.
With nrf_serial, I wanted to configure it the similar way, i.e. with DMA and using event handler to retrieve data. I'm however not receiving NRF_SERIAL_EVENT_RX_DATA event at all. Numerous NRF_SERIAL_EVENT_DRV_ERR events are generated instead, and I investigated the error flags to find out that it's either due to framing error (which is expected and non-critical) or overrun.
I tried various solutions to deal with overrun error, including extending the RX buffer and FIFO or adjusting UART IRQ priority, but that didn't help. I ended up reducing the baudrate to 38400 and the overrun error is gone, but I'm still not receiving RX_DATA events. My TX data seems to be transferred just fine, at least according to the p_written parameter returned from nrf_serial_write (I'm also getting NRF_SERIAL_EVENT_TX_DONE events).
Am I missing something obvious here? Thanks in advance for your help.
FWIW, my configuration is pretty straightforward, based on the minimal SDK example:
static void sleep_handler(void)
{
__WFE();
__SEV();
__WFE();
}
NRF_SERIAL_DRV_UART_CONFIG_DEF(m_uart0_drv_config,
RX_PIN_NUMBER, TX_PIN_NUMBER,
RTS_PIN_NUMBER, CTS_PIN_NUMBER,
NRF_UART_HWFC_ENABLED, NRF_UART_PARITY_EXCLUDED,
NRF_UART_BAUDRATE_38400,
UART_DEFAULT_CONFIG_IRQ_PRIORITY);
#define SERIAL_FIFO_TX_SIZE 256
#define SERIAL_FIFO_RX_SIZE 256
NRF_SERIAL_QUEUES_DEF(serial_queues, SERIAL_FIFO_TX_SIZE, SERIAL_FIFO_RX_SIZE);
#define SERIAL_BUFF_TX_SIZE 32
#define SERIAL_BUFF_RX_SIZE 1
NRF_SERIAL_BUFFERS_DEF(serial_buffs, SERIAL_BUFF_TX_SIZE, SERIAL_BUFF_RX_SIZE);
NRF_SERIAL_CONFIG_DEF(serial_config, NRF_SERIAL_MODE_DMA,
&serial_queues, &serial_buffs, on_serial_event, sleep_handler);
NRF_SERIAL_UART_DEF(serial_uart, 0);
