Polling Mode in Serial library

[sprasad]

Hello,

Can anyone point me to a good example for Polling mode using serial library?

I'm looking for an application in which I can poll the serial port for data. I went through API documentation and found that Serial library has a polling mode. Can anyone guide me in using that?

[Jørgen Holmefjord]

Hi,

I'm not aware of any examples of using polling mode, but this should be quite straight forward. You can start with the serial example, and modify it to your needs. You need to change the configuration as described in the documentation:

NRF_SERIAL_CONFIG_DEF(serial_config_polling, NRF_SERIAL_MODE_POLLING,

NULL, NULL, NULL, NULL);

Polling mode does not use QUEUES, BUFFERS, EVENT_HANDLER, or SLEEP_HANDLER, so you can remove all defines of these. You then need to call nrf_serial_write() and nrf_serial_read() to write and read the UART. The UART driver will operate in blocking mode, waiting for the operation to complete.

 

Best regards.
Jørgen

[sprasad]

Thank you for the guidance. I was able to read and write the data using polling mode.

I tried to replicate the same approach while using both UART0 and UARTE1 and tried to read the data from both UARTS. I'm able to read first character of UART0 only and after that the program gets stuck. Here is the code. Can you please suggest what could be done to overcome this?

        

// UART0 -> RX_PIN_NUMBER, TX_PIN_NUMBER (DEFAULT)
//UARTE1 -> ARDUINO_SDA_PIN, ARDUINO_SCL_PIN (DEFAULT)
        
        //In a loop
        
        ret = nrf_serial_read(&serial0_uart, &c, sizeof(c), NULL, 1000);
        if (ret != NRF_SUCCESS)
        {
            continue;
        }
        (void)nrf_serial_write(&serial0_uart, &c, sizeof(c), NULL, 0);
        (void)nrf_serial_flush(&serial0_uart, 0);
        
        ret = nrf_serial_read(&serial1_uart, &c, sizeof(c), NULL, 1000);
        if (ret != NRF_SUCCESS)
        {
            continue;
        }
        (void)nrf_serial_write(&serial0_uart, &c, sizeof(c), NULL, 0);
        (void)nrf_serial_flush(&serial1_uart, 0);
        (void)nrf_serial_flush(&serial0_uart, 0);
        

On commenting out each uart sections individually, the code works fine. Only when i put both together, it fails! What might be the reason?

       

[Jørgen Holmefjord]

How does it fail? Are you getting an error code from any of the function calls?

[sprasad]

When I entered debug mode with Seggar Embedded studio, I saw that the control is stuck at line no.6 (ret = nrf_serial_read(&serial0_uart, &c, sizeof(c), NULL, 1000)). If you can suggest some debugging approach that would help me debug this problem better, I can try that too.

[Jørgen Holmefjord]

Is it stuck on the line on the first iteration of the loop, or on second/later run? Did you check the suggestion from Jakub in the other thread where you posted your issue? Why are you not checking the error codes from nrf_serial_flush function calls?