libUARTe sending TX buffer twice

RE: libUARTe sending TX buffer twice

Jeff — Tue, 09 Feb 2021 15:37:54 GMT

Yes we did find it.

It wasn't an issue with libUARTE, rather an error in our code. It turned out to be a race condition due to setting a flag indicating that the port was in use after the transmission started rather than before. That allowed two transmissions to start at nearly the same time with the second overwriting the first's buffer.

We ended up needed to enable CLI and flash logging to debug this since it was only happening for us after a DFU without a debug board attached.

Getting flash logging to work with a DFU was a bit challenging too since we needed to protect the flash log area from being erased during the DFU. That involved setting NRF_DFU_APP_DATA_AREA_SIZE in the bootloader to account for the pages reserved in the app with FDS_VIRTUAL_PAGES_RESERVED, NRF_LOG_BACKEND_FLASH_START_PAGE and NRF_LOG_BACKEND_PAGES.

RE: libUARTe sending TX buffer twice

Stetina — Tue, 09 Feb 2021 14:54:36 GMT

Hello, Did you managed to solve that issue? I see similar behavior and I'm not able to debug it.

RE: libUARTe sending TX buffer twice

Susheel Nuguru — Fri, 04 Dec 2020 08:54:53 GMT

[quote user=""]I see the normal data getting transmitted and then about 7 ms later the cleared buffer is being transmitted. Normal operation would be to see a packet getting sent to the STM32 about every 120 ms.[/quote]

This sounds like a software bug inside app or library which can be time critical behavior.

Very hard to tell what is the issue here without seeing your usage of the libuarte and also how you handle the RX and TX events.