Increase UART speed using UARTE directly

[pressure_sensor_nonconn_adv]

I am using nRF52832 with UARTE with EasyDMA and communication speed of 912kB/s

I am wondering how I can increase the transmission speed using nrf_drv_uart_tx() in app_uart.c directly because app_uart_put() only puts one byte per time.

I tried doing using nrf_drv_uart_tx() directly with the length set to 4 bytes but this causes the Bluetooth device to not advertise anymore.

– do I need to use nrf_drv_uart_tx() in app_uart_fifo.c ?
– do I need to make changes on MCU side?
– Or Do you have an example code using nrf_drv_uart_tx() for faster UART transmission?

My code:

———————————-

for(i=0; i <= UINT32_DataSize-4; i += 4) /* must have at least 4 bytes left */
{
    while (app_uart_put_4(vBYTE_BuffToSend + i) != NRF_SUCCESS);
}

——————————-

uint32_t app_uart_put_4(uint8_t *byte_4)
{
    memcpy(tx_buffer_4, byte_4, 4);
    #if defined(ENABLE_LOG_BCP)
    NRF_LOG_ERROR("vBYTE_BuffToSend value = %d", tx_buffer_4[3]);
    #endif
    // max size of tx_buffer is #define UARTE0_EASYDMA_MAXCNT_SIZE 8
    ret_code_t ret = nrf_drv_uart_tx(&app_uart_inst, tx_buffer_4, 4);
    if (NRF_ERROR_BUSY == ret)
    {
        return NRF_ERROR_NO_MEM;
    }
    else if (ret != NRF_SUCCESS)
    {
        return NRF_ERROR_INTERNAL;
    }
    else
    {
        return NRF_SUCCESS;
    }
}

[Hieu]

Hi, 

– do I need to use nrf_drv_uart_tx() in app_uart_fifo.c ?\

I think you perhaps mean app_uart_put(), and if so, yes.
I am not sure if you can actually use nrf_drv_uart_tx(). If you are using app_uart.c, it should be wrapped up in the module and not accessible to you.

– do I need to make changes on MCU side?

No

– Or Do you have an example code using nrf_drv_uart_tx() for faster UART transmission?

"Yes." It is not nrf_drv_uart_tx(), but there are two examples with UART usage, I will refer to them below.

---

As you mentioned app_uart.c and app_uart_fifo.c, I believe you are using the UART Module library.
If so, I am afraid you are not using UARTE, but just a regular UART peripheral.
Among the two implementation of this module, app_uart_fifo.c added FIFOs for transmit and receive, and should give you better performance.

The example for this library locates at: <SDK Root>/examples/peripheral/uart
The documentation of the example is at: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/uart_example.html

---

If you wish to utilize the UARTE, please take a look at this Advanced UARTE Driver library: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/lib_libuarte.html

The example for this library locates at: <SDK Root>/examples/peripheral/libuarte
The documentation of the example is at: https://infocenter.nordicsemi.com/topic/sdk_nrf5_v17.1.0/libuarte_example.html

I have just tested both examples, changed the baud rate to 1 000 000 B/s, and they both worked as expected.

Best regards,

Hieu