For nRF52840 (Rigado BMD-340), SDK 15.0.0, custom board:
I'm trying to implement nrfx_uart directly to communicate to another microcontroller. I've configured it for blocking mode. In this mode, I've been able to transmit (115200 8N1) a message from the nRF52840 to the microcontroller, have the microcontroller successfully read and process the message, and then have the microcontroller successfully construct and transmit a response back to the nRF52840. All of this has been verified by breakpoints and oscilloscope traces.
However, this is where things go wrong. The nRF52840 nrfx_uart code generates an internal error when trying to receive the message sent by the microcontroller. Reading address 0x40002480 (UART0 ERRORSRC, right?) gives a value of 0x0D, i.e. BREAK, ERROR, and OVERRUN are all present.
The code is written modularly, but basically after pasting things together the listing looks like this:
main.c: main()
nrfx_clock_init(nrfx_clock_event_handler);
nrfx_clock_enable();
nrfx_clock_lfclk_start();
nrfx_clock_hfclk_start();
...
my_uart_init();
my_uart.c: my_uart_init()
{
nrfx_uart_config_t uartConfig = {
.pseltxd = pin_tx,
.pselrxd = pin_rx,
.pselcts = NRF_UART_PSEL_DISCONNECTED,
.pselrts = NRF_UART_PSEL_DISCONNECTED,
.p_context = NULL,
.hwfc = NRF_UART_HWFC_DISABLED,
.parity = NRF_UART_PARITY_EXCLUDED,
.interrupt_priority = NRFX_UART_DEFAULT_CONFIG_IRQ_PRIORITY
};
uartConfig.baudrate = NRF_UART_BAUDRATE_115200;
nrfx_err_t nrfx_err = nrfx_uart_init (&(bus->nrfx_uart), &uartConfig, BLOCKING_MODE);
APP_ERROR_CHECK(nrfx_err);
nrfx_uart_rx_enable(&(bus->nrfx_uart));
}
... sometime later an event happens and I transmit a message successfully then attempt a read:
my_uart.c: read(nBytes)
{
uart_err_t uartErr = UART_RETRY; //uart_err_t is my typedef
while(uartErr == UART_RETRY)
{
uartErr = _uart_errorHandler(nrfx_uart_rx(&(uart_interface->bus->nrfx_uart), rxBuffer, nBytes));
}
return uartErr;
}
Some additional context:
This is the first time I've used a Nordic BLE module. I've been going through the learning curve fairly well over the past few months, but maybe I'm missing something simple that more experienced users would know. I started the application from ble_app_uart, but have commented out all the BLE functionality for now (i.e. ble_stack_init etc. are not called). Instead, I've only started lfclk and hfclk directly through nrfx_clock and a number of other unrelated code modules as well. Also, I've implemented nrfx_twi similarly to how I want to implement nrfx_uart, and it's working perfectly.
What I've tried so far:
I've tried different combinations of when to use rx_enable and rx_disable around the nrfx_uart_rx function, ultimately settling for using it in my my_uart_init() function. I've added and removed delays between messages being sent and received. I've looked at different forum posts and didn't see one line up exactly with what I'm experiencing, but I did enable hfclk just in case I needed to explicitly start it (nrf52840 product spec seems to imply that I don't need to, but I'm new to nRF so I could be wrong...).
What I'm going to try in the mean time:
While waiting for help here, I'm going to try switching to nrfx_uarte and, if not, implement app_uart in my uart.c file, but I'd rather keep with nrfx_uart if I can for consistency.
How you can help:
Do you have any ideas about what else I can try to get nrfx_uart_rx to work? I greatly appreciate any and all advice. Thank you!
