nrf_libuarte_async TX issue

[linfan68]

Basically, I cannot do continuous TX with nrf_libuarte_async:

Here is simple reproduce:

    static uint8_t text[] = "===TICK===\r\n";
    static uint8_t text_size = sizeof(text);
    static uint8_t text2[] = "+++TOCK+++\r\n";
    static uint8_t text2_size = sizeof(text2);
    while (true)
    {
        err_code = nrf_libuarte_async_tx(&libuarte, text, text_size);
        for (size_t i = 0; i < 1000000; i++)
        {
        }
        err_code = nrf_libuarte_async_tx(&libuarte, text2, text2_size);
        for (size_t i = 0; i < 10000000; i++)
        {
        }
    }

It only output ===TICK=== and no +++TOCK+++

Here is what I've tried:

1. I can confirm that NRF_LIBUARTE_ASYNC_EVT_TX_DONE event has been triggered during the for loop in between

2. If I increase the delay by for loop, both data got through

3. both calls returns 0x00 (SUCCESS)

4. If I put a breakpoint in between, of the NRF_LIBUARTE_ASYNC_EVT_TX_DONE  event, it works

5. I've tried in another project with RTOS and use osDelay to test the gap needed for second transmission, it seems ~300 ms is needed.

help please....

[linfan68]

[Update]

It's not libuarte related, it seems like an EasyDMA issue.

I got another repro without using libuarte, the second message is not showing.

volatile static bool _gotTxDone = false;
void UARTE0_UART0_IRQHandler(void)
{
    if (nrf_uarte_event_check(NRF_UARTE0, NRF_UARTE_EVENT_ENDTX)) {
			nrf_uarte_event_clear(NRF_UARTE0, NRF_UARTE_EVENT_ENDTX);
			_gotTxDone = true;
    }

    return;
}

// ... main...
  uint8_t text[] = "===TICK===\r\n";
  uint8_t text_size = sizeof(text);
  uint8_t text2[] = "+++TOC+++\r\n";
  uint8_t text2_size = sizeof(text2);

  while (true) {
		NRF_LOG_INFO("=========");
		NRF_LOG_FLUSH();

		_gotTxDone = false;
    NRF_UARTE0->TXD.PTR = (uint32_t)text;
    NRF_UARTE0->TXD.MAXCNT = (uint32_t)text_size;
    NRF_UARTE0->TASKS_STARTTX = 1;
    while (!_gotTxDone) {; }

		for (size_t i = 0; i < 100000; i++) { }
		
		_gotTxDone = false;
    NRF_UARTE0->TXD.PTR = (uint32_t)text2;
    NRF_UARTE0->TXD.MAXCNT = (uint32_t)text2_size;
    NRF_UARTE0->TASKS_STARTTX = 1;
    
    
    while (!_gotTxDone) {; }
    NRF_LOG_FLUSH();
		for (size_t i = 0; i < 10000000; i++) { }
  }

[linfan68]

OK... problem solved.

This is wrong way to prepare test data:

static uint8_t text[] = "UART example started.\r\n Loopback:\r\n";
static uint8_t text_size = sizeof(text);

(this is in the libuarte example code!)

Basically, the sizeof(text) will include the '\0' which is 0x00 as part of the buffer. Then UART will send the 0x00 to the terminal.

My serial terminal (like others) don't like 0x00 showing in ascii view.

But this is a ascii message... very misleading example.....

Anyway, problem solved.