Sometimes only first char sent over UART using app_uart_fifo, then dead silent

RE: Sometimes only first char sent over UART using app_uart_fifo, then dead silent

Susheel Nuguru — Fri, 19 Aug 2016 06:40:42 GMT

I do not think this should be the problem unless the timer interrupt callback time is like a millisecond or so. Try to change the priority of the FIFO to higher priority, see if it helps. if your app can compromise timer callback lantency little bit, then I see no problem in increasing uart priority.

RE: Sometimes only first char sent over UART using app_uart_fifo, then dead silent

Pierre Landau — Thu, 18 Aug 2016 01:04:02 GMT

We see this happening rather consistently in something we are trying to develop. Current theory is that the app_uart_init call specifies APP_IRQ_PRIORITY_LOW, and we are adding things to the send FIFO from a timer callback that is also at that priority level. Perhaps the priority levels need to be different for the system to be able to process the UART interrupt before returning from the caller.

RE: Sometimes only first char sent over UART using app_uart_fifo, then dead silent

Susheel Nuguru — Mon, 15 Aug 2016 06:54:33 GMT

Sorry for late response, you might have already found the reason by now, in case you did not, then the only way to find out where the software gets stuck is to run your programmer in debugger. If you are writing your program in Keil then you can also compile it in keil (just for debugging purpose). Errors like this most probably will not differ with compilers

RE: Sometimes only first char sent over UART using app_uart_fifo, then dead silent

pontusarfwedson — Fri, 12 Aug 2016 08:38:04 GMT

Yes, I realize that. But what is currently happening is that it tries to send message over UART, gets stuck after first character, then does NOT reboot. So then it appears that the error for some reason is not being handled. How is this a possibility?

RE: Sometimes only first char sent over UART using app_uart_fifo, then dead silent

Susheel Nuguru — Fri, 12 Aug 2016 08:28:45 GMT

APP_ERROR_CHECK will reset for any other err code apart from NRF_SUCCESS. If you are getting NRF_ERROR_NO_MEM then you are writing faster in fifo than reading it.

RE: Sometimes only first char sent over UART using app_uart_fifo, then dead silent

pontusarfwedson — Fri, 12 Aug 2016 07:20:43 GMT

Thanks for reply. I assume that the reboot is due to APP_ERROR_CHECK. I develop in Kiel but do however compile with own gcc compiler. Therefor, presumable cannot debug with breakpoints. But are there any scenario where APP_ERROR_CHECK will behave the way I explained? The only logical error code is NRF_ERROR_NO_MEM.

Sorry for not doing more research. I have not investigated the APP_ERROR_CHECK that much but I can see now that it makes it stop advertising and NVIC_SystemReset(), no matter what the ERROR_CODE is. So the chip should therefor reboot every time i get NRF_ERROR_NO_MEM from uart. However, does not seem to do so.

RE: Sometimes only first char sent over UART using app_uart_fifo, then dead silent

Susheel Nuguru — Fri, 12 Aug 2016 06:41:44 GMT

if the reboot is because of the APP_ERROR_CHECK then i suggest you to compile it with no optimizations, and set a breakpoint at this check and see what error_code is returned.