Call to app_uart_put() not putting anything on the TX Line

[Sami]

Hello,

I've been trying to get my call to app_uart_put() to actually place bytes on the TX pin. Interestingly enough, my call to app_uart_get() works fine and is able to receive all the commands on the RX pin. I am using SDK v17.0.2. 

My code that initializes the UART is fairly boilerplate:

   if (!uart_instance_activated)
    {
        uart_instance_activated = true;
        uint32_t err_code = NRF_SUCCESS;
        const app_uart_comm_params_t comm_params =
        {
            UART_RX_PIN,
            UART_TX_PIN,
            UART_RTS_PIN_NUMBER,
            UART_CTS_PIN_NUMBER,
            UART_HWFC,
            false,
            NRF_UART_BAUDRATE_115200
        };

        APP_UART_FIFO_INIT(&comm_params,
                       UART_RX_BUF_SIZE,
                       UART_TX_BUF_SIZE,
                      uart_error_handle,
                APP_IRQ_PRIORITY_LOWEST,
                              err_code);

        APP_ERROR_CHECK(err_code); 
    }

My code that calls app_uart_put()

uint8_t transportSend( const uint16_t bufferSize, uint8_t *pBuffer )
{
    if ( pBuffer == NULL )
    {
        NRF_LOG_INFO("NULL?");
        return TRANSPORT_ERROR;
    }

    uint32_t status = NRF_SUCCESS;

    while (app_uart_put(START_BYTE) != NRF_SUCCESS);
    nrf_delay_ms(10);

    for ( uint16_t i = 0; i < bufferSize; i++ )
    {
        //NRF_LOG_INFO("pBuffer[%d] = %d", i, pBuffer[i]);
        // UART is spaming 0xFF so it has to be escaped
        if ( ( pBuffer[i] == START_BYTE ) ||
             ( pBuffer[i] == STOP_BYTE ) ||
             ( pBuffer[i] == ESCAPE_BYTE ) ||
             ( pBuffer[i] == 0xFF ) )
        {
            //status = app_uart_put( ESCAPE_BYTE );
            while (app_uart_put(ESCAPE_BYTE) != NRF_SUCCESS);
            nrf_delay_ms(10);

            while (app_uart_put(escapeByte( pBuffer[i] )) != NRF_SUCCESS);
            nrf_delay_ms(10);
        }
        else
        {
            while (app_uart_put(pBuffer[i]) != NRF_SUCCESS);
            nrf_delay_ms(10);
        }
    } // end of for-loop

    while (app_uart_put(STOP_BYTE) != NRF_SUCCESS);
    nrf_delay_ms(10);
  
    return TRANSPORT_SUCCESS;
}

and Like I said, my code that calls app_uart_get() works just fine:

static int cala_getChar()
{
    uint8_t input = 0;
    app_uart_get(&input);
    return input;
}

Is app_uart_put() not being called correctly? Doubled checked sdk_config.h and NRFX_UART_ENABLED is 1

[Sami]

Hi Simon,

CLI instance was still "busy" from a previous request of it. 

How did I finally solve this without modifying the SDK? Well here is my code. The key element here is that I have to call the Nordic App Scheduler in order for the internal state flag of the CLI process to "clear" (not be NRF_ERROR_BUSY):

// Misc Rpc Cmd
static void cmd_misc_rpc_on(nrf_cli_t const *p_cli, size_t argc, char **argv)
{
    if (p_cli == NULL)
    {
        NRF_LOG_INFO("Null pointer found in %s() @line %d\n", __FUNCTION__, __LINE__ );
        return;
    }

    ASSERT(p_cli);
    ASSERT(p_cli->p_ctx && p_cli->p_iface && p_cli->p_name);

    // Business end of the command:
    NRF_LOG_INFO("RPC Activated!");

    if (!m_rpcActivationFlag)
    {
        // Schedule a graceful teardown of the CLI process and start-up of a
        // generic UART instance. A scheduled task will ensure that the CLI
        // interal state will update itself correctly:
        uint32_t err_code = app_sched_event_put( NULL, 
                                                    0, 
                              cliGracefulTeardownCb );
        if (err_code != NRF_SUCCESS)
        {
            NRF_LOG_INFO("app_sched_event_put() failed in %s() invokation",
                          __FUNCTION__);
        }
    }
}

static void cliGracefulTeardownCb( void *pData, const uint16_t size )
{
    UNUSED_PARAMETER(pData);
    UNUSED_PARAMETER(size);

    m_rpcActivationFlag = true;

    // Halt the CLI process over UART so that RPC over UART can take
    // control of the TX/RX pins.
    cli_stop();

    // Create an instance of UART with the appropriate parameters:
    uint32_t err_code = NRF_SUCCESS;
    const app_uart_comm_params_t comm_params =
    {
                UART_RX_PIN,
                UART_TX_PIN,
        UART_RTS_PIN_NUMBER,
        UART_CTS_PIN_NUMBER,
                  UART_HWFC,
                      false,
#if defined (UART_PRESENT)
    NRF_UART_BAUDRATE_115200
#else
          NRF_UARTE_BAUDRATE_115200
#endif
        };

    APP_UART_FIFO_INIT(&comm_params,
                   UART_RX_BUF_SIZE,
                   UART_TX_BUF_SIZE,
                  uart_error_handle,
            APP_IRQ_PRIORITY_LOWEST,
                          err_code);
    {
        APP_ERROR_CHECK(err_code); 
    }
}

As always, I appreciate the DevZone's help!

[Sami]

void cli_stop(void)
{
    ret_code_t ret = NRF_SUCCESS;

#if CLI_OVER_USB_CDC_ACM
    ret = nrf_cli_stop(&m_cli_cdc_acm);
    APP_ERROR_CHECK(ret);
#endif

#if CLI_OVER_UART
    NRF_LOG_INFO("Stopping CLI");
    // Please note, system must reset in order to recover normal CLI over-UART
    // operations. 
    ret = nrf_cli_stop(&m_cli_uart);
    if (ret != NRF_SUCCESS)
    {
        NRF_LOG_INFO("nrf_cli_stop() failed!");
    }

    // Unintialize the CLI instance.
    ret = nrf_cli_uninit(&m_cli_uart);
    if (ret != NRF_SUCCESS)
    {
        NRF_LOG_INFO("nrf_cli_uninit() failed!");
    }
#endif

}