No RX on UART

[Sergy]

Hi,

I'm using 51822 to control GSM module via UART (57600, no flow control). My device is USB and battery powered. After I program the chip I HAVE to disconnect all the power in order to start system clean and have it working. If I don't completely remove power on start nrf will send commands to GSM module, GSM module will recognize them and send a reply to nrf, but nrf won't get anything on RX (I'm using simple UART without interrupt and without softdevice).

What could it be? I also don't use 32khz xtal, so it synthesises clock from hf crystal.

[Susheel Nuguru]

uint32_t error;
       if(NRF_UART->EVENTS_ERROR !=0)
       {
            NRF_UART->EVENTS_ERROR = 0;
            error = NRF_UART->ERRORSRC;
            NRF_UART->ERRORSRC = error;

// flush the RX FIFO by reading and ignoring them

 

   while (NRF_UART->EVENTS_RXDRDY != 0) 
    { 
        error = NRF_UART->RXD; 
        NRF_UART->EVENTS_RXDRDY = 0;
        //Give a moment for more data in FIFO to move into RXD register
        nrf_delay_ms(1);
    }
   }