APP_UART_COMMUNICATION_ERROR in nRF52

[naman.trivedi]

Hi,

I have my application working on NRF SDK11 on NRF52832 with softdevice 2.0. I am porting the application to SDK 14 and SD 5.0. I am facing APP_UART_COMMUNICATION_ERROR error.

UART works fine for few packets but when I transfer very large file in small chunks continuously over UART, after few packets, I get APP_UART_COMMUNICATION_ERROR error with reason: OVERRUN. I have set TX_BUF_SIZE to 256 and RX_BUF_SIZE to 8 in application and I also played with the sizes but no success.  I am using FIFO with UART and have compiled app_uart_fifo.c in my application. I am not using flow control in my application ( as we are not using RTS, CTS pins. )  Baudrate is 115200 and I tried lower rates till 2400 too but no success. I was not facing this issue with older SDK ( v11 ). 

Any help on this issue?

[naman.trivedi]

Any help here?

[ovrebekk]

Hi Naman

Do you have EASY_DMA enabled or not?

Best regards
Torbjørn

[naman.trivedi]

Yes, UART_EASY_DMA_SUPPORT is 1 in sdk_config.h

[ovrebekk]

Hi 

Have you tried to benchmark the occurrence of interrupts in your application?

How large did you try to make the RX_BUF_SIZE?

Do you know the size of the "chunks", and how often they are sent?

A potential problem is that the driver won't give you an interrupt until the buffer is full, and then you have very little time to prepare a new buffer if you are in the middle of a UART transaction. 

Ideally you want to update the buffers in between the chunks, so that you are less pressed on time. 

Best regards
Torbjørn

[naman.trivedi]

1. I couldn't understand your first point: 

"Have you tried to benchmark the occurrence of interrupts in your application?"

2. I tried with Rx buffer size 1024 and Tx 512. The UART chunk is of 485 bytes and the total size of the file is around 220 Kb. 

[naman.trivedi]

According to my understanding, UART will give APP_UART_DATA_READY after receiving every single byte from UART and then we have to copy that to our local buffers. Is that correct? Also, one common behavior I have observed is that I get error after sending a reply over UART.

[naman.trivedi]

I was able to partially solve the issue by putting delay on the other side. So closing this thread now. Thanks for replies!

[strengthstrong]

how  solve?