[NRF51822QFAC][SDK11] How to recover Uart errors

[Lalit Kumar]

Hi,

I'm trying to interface SIM808 with nrf51822 over uart using nrf_drv_uart. Everything works well for some time, but then uart starts reporting error code 1, NRF_UART_ERROR_PARITY_MASK, for all transactions on uart. Re-initializing the uart doesn't correct it. Also the time after which error starts appearing is also random, varies from 15 minutes to 1 hour. The problem is not with the module as when the error occurs, I can still communicate with the module using external uart to usb. Here is what I think is relevant information:

• Baudrate is 115200
• Tx is blocking
• Listen to rx for 20ms
• Max transaction size for rx is 10 bytes

I can upload the code, if necessary.

Hoping for a positive response and thanks in advance :)

[Lalit Kumar]

nRF51 clock is 16Mhz Xtal, sim808 has an internal clock, specs are not available for that. If I connect other uart device to sim808 module without resetting, it works fine. If I reset the module, then also it works fine. Clock jitter looks prime suspect, but I doubt that can be diagnosed without altering the clock of both modules. Also if I change the baud rate to 460800, error frequency increases, but at bps of 230400, error frequency decreases a lot, minimum error time reduces to 2 hours at 230400. Can anything be done without changing the hardware?