nrfx_uarte_rx() hangs

[Bruno Randolf]

Hello! I have a serial device (RN8209 power meter) which is connected by UART to a nRF52832 with 4800 Baud. I am using SDK17 nrfx UARTE to access it, but I have observed, that sometimes nrfx_uarte_rx() hangs. It hangs in:

modules/nrfx/drivers/src/nrfx_uarte.c:505

} while ((!endrx) && (!rxto) && (!error));

Interestingly I can avoid hanging the UART by placing a nrf_delay_us(100); right after the call to nrfx_uarte_rx();

Apart from the initialization (which works fine), the communication to the device is mostly: TX 1 byte, RX 2-5 bytes and repeated. It looks like the second time I do that, the RX hangs. Any ideas?

[Kenneth]

Can't think of anything, you are using very low badurate compared to normal, so it might be that you are hitting an unknown timing corner case. Maybe you can try using nrf_drv_uart_rx_ready() first to check if there is any data before calling nrf_drv_uart_rx().

In general I recommend to use: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/lib_libuarte.html 

Also make sure you are using the latest nRF5 SDK v17.1 if you are not already.

Kenneth

[Bruno Randolf]

Since my workaround with the delay didn't work 100% of the time, I have now switched to libuarte and it seems to work fine. And yes, I am using SDK v17.1. Thank you!