UARTE: uart_fifo_read() - 4th byte always 0x00

RE: UARTE: uart_fifo_read() - 4th byte always 0x00

Kenneth — Tue, 16 Aug 2022 12:37:35 GMT

[quote user="Brett"]Do you have a link or video that I can review which shows how to connect a logic analyser onto the nrf9160dk, so that I can monitor between the 52840 and 9160 chips.[/quote]

You should only need to connect GND to common ground between DK's. Then connect the RXD and TXD pins to two input pins of the logic analyzer, then start tracing from the logic analyzer, if you set the baudrate in the logic analyzer you should be able to observe the data on byte level.

Kenneth

RE: UARTE: uart_fifo_read() - 4th byte always 0x00

Brett — Tue, 16 Aug 2022 11:41:14 GMT

Hi Kenneth,

I can open a new issue if required, but I am still working on the same problem - maybe.

Do you have a link or video that I can review which shows how to connect a logic analyser onto the nrf9160dk, so that I can monitor between the 52840 and 9160 chips.

All runs fine for about 10 minutes and then I get all 0x00's on the 9160 and I am not sure if its the 52840 or the 9160. For some reason debug on the 52840 is not working the way I need it to, and its hard to see where the problem is.

regards
-brett

RE: UARTE: uart_fifo_read() - 4th byte always 0x00

Georgiy Lutsenko — Thu, 28 Jul 2022 15:46:50 GMT

Hi all
I had a similar issue.
I am using 9160 and see the same problems with UART.
I checked the sent data from another device with an analyzer. (The data is correct).
But there is a problem on the 9160 side.
For receiving and sending I use interrupts:

static void DtRS485_uartCallback(const struct device *pDev, void *user_data)

{

uart_irq_update(pDev);

if (uart_irq_rx_ready(pDev)) {

uint8_t data_length = 0;

data_length = uart_fifo_read(pDev, uartBuf, sizeof(uartBuf));

if (spRxFifo != NULL) {

if (data_length > 0) {

DtFIFO_pushBuffer(spRxFifo, uartBuf, data_length);

}

if (uart_irq_tx_ready(skpUart)) {

uint16_t size = DtFIFO_availableForRead(spTxFifo);

if (size > 0) {

DtGPIO_pinSet(DIR_RS485, true);

DtFIFO_popBuffer(spTxFifo, sBufTX, size);

uart_fifo_fill(pDev, sBufTX, size);

}

if (uart_irq_tx_complete(skpUart)) {

uart_irq_tx_disable(skpUart);

DtGPIO_pinSet(DIR_RS485, false);

}

}

What is the UART interrupt priority?

Thanks.

Best regards,

Georgiy

RE: UARTE: uart_fifo_read() - 4th byte always 0x00

Kenneth — Wed, 27 Jul 2022 14:45:48 GMT

[quote user="Brett"]

free(p_page_data);

Q: Could this free happen before the data is completed on the UART ?

[/quote]

Yes, since the nrf_libuarte_async_tx() occurs asynchronous (non-blocking).

Kenneth

RE: UARTE: uart_fifo_read() - 4th byte always 0x00

Brett — Wed, 27 Jul 2022 12:27:39 GMT

Hi Keneth,

I have it working, but not sure really why, hoping you can clarify something.

In the original code, after the async_tx call,

err_code = nrf_libuarte_async_tx(&libuarte, (uint8_t *)p_page_data, page_size );

I have a free call, too free from the malloc.

free(p_page_data);

Q: Could this free happen before the data is completed on the UART ?

Why I ask this is because if I add the following delay between the tx and free - it all works and I dont miss any random packets.

nrf_delay_ms(1);

Fails:

err_code = nrf_libuarte_async_tx(&libuarte, (uint8_t *)p_page_data, page_size );
NRF_LOG_INFO("return nrf_libuarte_async_tx : %d", err_code);
APP_ERROR_CHECK(err_code);
free(p_page_data);

Works:

err_code = nrf_libuarte_async_tx(&libuarte, (uint8_t *)p_page_data, page_size );
NRF_LOG_INFO("return nrf_libuarte_async_tx : %d", err_code);
APP_ERROR_CHECK(err_code);
nrf_delay_ms(1);
free(p_page_data);

The confusing part to me is, its always the 4th (occasionally the 3rd) packet that gets dropped, maybe thats due to timing?

regards
-brett

RE: UARTE: uart_fifo_read() - 4th byte always 0x00

Brett — Wed, 27 Jul 2022 04:24:33 GMT

The 'static volatile' didnt make any difference - same issue.

I have just ordered a logic analyzer, so I will get back to you in a few days. i will keep testing other things, and if it magically starts works, I will update this case.

regards
-brett

RE: UARTE: uart_fifo_read() - 4th byte always 0x00

Kenneth — Tue, 26 Jul 2022 14:05:24 GMT

Can you try to set all uart buffers (on both peers) to 'static volatile' to ensure they are not reused for other purposes by the compiler?

If that does not help, do you have access to a logic analyzer so you can look at the serial data, just to confirm if it's indeed nRF52840 or nRF9160 that is the problem here?

Kenenth