uarte doesn't send data

[Stavros Makridis]

Hi everyone,

I am trying to use the nrfx_uarte driver. I did the following:

(a) setup driver

nrfx_uarte_config_t uarte_config = {
    .pseltxd = RX_PIN_NUMBER,
    .pselrxd = TX_PIN_NUMBER,
    .pselcts = CTS_PIN_NUMBER,
    .pselrts = RTS_PIN_NUMBER,
    .p_context = NULL,
    .hwfc = NRF_UARTE_HWFC_DISABLED,
    .parity = NRF_UARTE_PARITY_EXCLUDED,
    .baudrate = NRF_UARTE_BAUDRATE_115200,
    .interrupt_priority = 2
};

APP_ERROR_CHECK(nrfx_uarte_init(&uarte, &uarte_config, uarte_event_handler));

(b) setup the event handler

static void uarte_event_handler(nrfx_uarte_event_t const *p_event, void *p_context)
{
    static uint8_t step = 0;
    static uint8_t stopCount = 0;
    
    if (p_event->type == NRFX_UARTE_EVT_TX_DONE)
    {
        tx_done = true;
        rx_done = false;
        rx_count = 0;
        nrfx_err_t error = nrfx_uarte_tx(&uarte, "Hello", 5);
        NRF_LOG_INFO("Data Sent");
    }
    
    if (p_event->type == NRFX_UARTE_EVT_RX_DONE)
    {
        uint8_t inbyte = 0;
    
		if (p_event->data.rxtx.bytes > 0)
		{
			inbyte = *p_event->data.rxtx.p_data;
		
			if ((inbyte != ' ') && (inbyte != '\0'))
			{
				char inbuffer[2] = {inbyte, '\0'};
				strcat(rx_buffer, inbuffer);
		
				if ((strstr(rx_buffer, "OK\r\n") != NULL) || (strstr(rx_buffer, "ERROR\r\n") != NULL))
				{
					rx_done = true;
					NRF_LOG_INFO("Data Received");
					NRF_LOG_PUSH(rx_buffer);
					//NRF_LOG_HEXDUMP_INFO(rx_buffer, rx_count);
				}
			}
			nrfx_uarte_rx(&uarte, m_int_buffer, 1);
		}
    }
    
    if (p_event->type == NRFX_UARTE_EVT_ERROR)
    {
		trfx_error = true;
		NRF_LOG_INFO("Error Occured");
		APP_ERROR_CHECK(p_event->data.error.error_mask);
	}
}

(c) finally tried to send some testing data

nrfx_err_t error = nrfx_uarte_tx(&uarte, "Hello", 5);

I don't get any error but I don't get any data either.

I put to lines that set/reset TX pin inside a while(true) loop and I got a square wave of ~330KHz on the oscilloscope, so I assume that the physical pin in terms of hardware is fully functioning.

Am I missing something? Please any advice is more than welcome.

Best regards,

Stavros Makridis.

[Jared]

Hi,

The nrfx_uarte_tx() function uses EasyDMA and therefore requires the transfer buffer to be placed in the Data RAM region. Pass the data as a buffer and it will be placed in the Data RAM region. 

[Stavros Makridis]

Hi Jared,

First of all thank you for your immediate response.

I followed your suggestion and your are right. The tx done interrupt triggered but I still don't see data coming out. I have checked it with both a uart to USB converter and a oscilloscope.

As I mentioned earlier, I tried to toggle TX pin in a while loop and I got a 330KHz square wave on oscilloscope so I believe there is no hardware issue at least on this pin. 

Any ideas?

[hmolesworth]

You can use this as an interview question - spot the bug:

    .pseltxd = RX_PIN_NUMBER,
    .pselrxd = TX_PIN_NUMBER,

Hint: tx on TX

[Stavros Makridis]

omg.....you are so right......I feel stupid now

Thanks so much.....I checked again and again and again if RX_PIN_NUMBER and TX_PIN_NUMBER point to the correct physical pins but I have never thought to check the assignment to struct fields.

Thank you so much.