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

Question

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 · Accepted Answer

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
", __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!

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

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