UARTE driver configuration for nRF52840

[Tobamalau]

Hallo,

I want to use the UARTE instead of the UART to transmit some audio data to DK. The Basic Project is the i2s example in nRF5_SDK_15.3.0_59ac345.

I implemented the UARTE drive but I get the error: multiple definition of `nrfx_uarte_0_irq_handler'. In some articles I found the same issue. There the solution should be to remove nrf_uarte.c from build. But then I get another error: undefined reference to `nrfx_uarte_init'. The sdk config file is attached.

#include "sdk_config.h"
#include "nrf_delay.h"
#include "app_util_platform.h"
#include "app_error.h"
#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"
#include "nrf_drv_timer.h" //Timer
#include "nrfx_uarte.h"


....

void nrfx_uarte_0_irq_handler(void)
{
    // Code
}
int main(void)
{
    nrfx_uarte_t m_uart = NRFX_UARTE_INSTANCE(0); 
    nrfx_uarte_config_t m_uart_config = NRFX_UARTE_DEFAULT_CONFIG;
    
    nrfx_uarte_init(&m_uart, &m_uart_config, nrfx_uarte_0_irq_handler);
    
    .....
    
    

/cfs-file/__key/support-attachments/beef5d1b77644c448dabff31668f3a47-bdd7d0a8852e43c099ef91cdc3026793/sdk_5F00_config.h

any tips?

[Vidar Berg]

Hallo,

Yes, the third argument for nrfx_uarte_init() is supposed to be a user-provided callback that will be invoked on driver events. nrfx_uarte_0_irq_handler() is the IRQ handler, and is already defined inside the driver, hence the multiple definition error.

Include nrf_uarte.c in your build again, then define your own callback as shown below:

void my_uart_callback(nrfx_uarte_event_t const * p_event,
                      void *                     p_context)
{
    //TODO: Handle 'p_event'
}


int main(void)
{
    nrfx_uarte_t m_uart = NRFX_UARTE_INSTANCE(0); 
    nrfx_uarte_config_t m_uart_config = NRFX_UARTE_DEFAULT_CONFIG;
    
    nrfx_uarte_init(&m_uart, &m_uart_config, my_uart_callback);
    
    .....
    

Link to driver documentation in case you haven't seen it: UART

[Tobamalau]

Thanks that was the bug.

Now the UARTE works but but just as slow as the UART.

I send from pc 324 byte to DK and I have meassured the time between uarte_rx and the event NRFX_UARTE_EVT_RX_DONE. I get 32ms to recive the 324 byte. Its just 81kbit/s.

   switch(p_event->type)
   {
      case NRFX_UARTE_EVT_TX_DONE:
         timerCnt = 0;
         nrfx_uarte_rx(&m_uart, rxUarteBuffer, sizeof(rxUarteBuffer));
         break;

      case NRFX_UARTE_EVT_RX_DONE:
         UpdI2SBuffer = true;
                     uint8_t txBuffer[] = {0x72};
            nrfx_uarte_tx(&m_uart, txBuffer, sizeof(txBuffer));
         break;

Do I have a config issue? Is it maybe faster when I connect to the nRF USB on the Board instead the Jlink USB?

void m_uart_context_callback()
{

}
uint8_t uarte_init()
{
    
    nrfx_uarte_config_t m_uart_config = {//= NRFX_UARTE_DEFAULT_CONFIG;
                      TX_PIN_NUMBER,               ///< TXD pin number.
                      RX_PIN_NUMBER,               ///< RXD pin number.
                      CTS_PIN_NUMBER,              ///< CTS pin number.
                      RTS_PIN_NUMBER,              ///< RTS pin number.
                      //NULL,
                      m_uart_context_callback,                        ///< Context passed to interrupt handler.
                      UARTE_CONFIG_HWFC_Disabled,              ///< Flow control configuration.
                      UARTE_CONFIG_PARITY_Excluded,            ///< Parity configuration.
                      UARTE_BAUDRATE_BAUDRATE_Baud115200,      ///< Baudrate.
                      NRFX_UARTE_DEFAULT_CONFIG_IRQ_PRIORITY,  ///< Interrupt priority.
    };
    return nrfx_uarte_init(&m_uart, &m_uart_config, m_uart_callback);

[Vidar Berg]

Hi,

I wouldn't expect any difference in throughput between UART and UARTE as long as you're able to avoid overflow of the internal RX FIFO buffer, the baud rate clock speed defines the transfer rate. The UARTE's advantage is that it can receive large chunks of data without requiring CPU involvement.

81 kbit/s does not seem not too far from the 92 kbit/s theoretical max at this baud rate. I think you should start the counter at the reception of the first byte. Also, check if you're receiving any error events (dropped bytes) and if the PC is sending a continuous stream of bytes without any pauses.