UART communication problems between nrf52840 DK-borad and nRF9160 DK-board

[duxinglang]

I tried to debug UART communication between 52840 development board and 9160 development board. I sent 9 bytes of data from 52840 side, but I only received 8 bytes of data on 9160 side. After many tests, I found that 9160 can only receive 8 bytes of data at a time. Later, I used UART to USB connection cable to connect the output pin of 52840 to the PC, and found that the output was really 9 bytes of data. Why can my 9160 only receive 8 bytes of data? the codes and results is like this:

[Martin Lesund]

Hi Duxinglan,

Your implementation seems unnecessarily complicated and is most likely the reason why you get the incorrect results.

Please instead use this sample as reference: https://github.com/Rallare/fw-nrfconnect-nrf/blob/nrf9160_samples/samples/nrf9160/uart/src/main.c
Here is the UART API doc

[duxinglang]

I've tested it with this example, and unfortunately it won't receive any data.as I am now receiving data byte by byte, it will receive the data, but it will receive a callback message from UART_CB several times in the process, which will truncate my data.

[duxinglang]

Now a miracle has happened! when I print out each byte of data on the receiving end, the callback message doesn't appear more than once, so I can receive a full frame of data!It seems that the previous error occurred because I was reading data faster than UART could receive data. Adding a LOG to print is equivalent to a waiting time, but I don't know why this problem occurs.