NRF_LOG/RTT backend suddenly stops working (SDK15.0.0)

[OlaHallstrom]

Hi,

I'm using NRF_LOG to print information via RTT backend (RTT viewer v6.20) and it has been working so far. After adding a single call to a function that reads 128 bytes of data from an RFID tag to a RAM buffer (RFID reader IC over SPI) the logs stop working. NRF_LOGs work fine up to that point. I'm not printing anything or calling any NRF_LOG function when doing this (unless the NRFX spi driver is doing it in the background?). The execution continues normally unless i call NRF_LOG_FLUSH which will hang. I tried to read the RFID tag memory in chunks rather than the single 128 byte read. Doing that and NRF_LOG continues to work even efter the calls, but I end up in other problems with the RFID parts so I can't do this way.

If using Segger_RTT_printf() when NRF_LOG has crashed I will get output so it seems to work at a lower level.

Application is using a softdevice.

I've tried experimenting with various settings of buffer sizes etc for NRF_LOG in sdk_config.h without any luck.

Any suggestion of what might be causing this behaviour or what to check?

BR

//Ola

[OlaHallstrom]

Found the solution!

My RFID read call was using a too small buffer causing write in unknown memory, and Hardfault exception. After fixing this, NRF_LOG is alive again. Sorry for bothering you with this but it kind of helped me just summarizing the problem.

//Ola