UARTE communication using CONFIG_UART_INTERRUPT_DRIVEN dropping data after 8 bytes

RE: UARTE communication using CONFIG_UART_INTERRUPT_DRIVEN dropping data after 8 bytes

Jared — Thu, 27 Aug 2020 02:26:06 GMT

The only solution that I've found for this is a as follows:

1. Use the ASYNC API as I was before (Github Link)

2. On the other device, pad any remaining bytes with 0's so they always align with the size of the RX buffer on the nRF9160

3. When trying to figure out message boundaries, the first byte indicates how many data bytes are in a stream. So technically the following byte after the last in the "frame" would be the size. I now disregard any size of 0.

It's a little clunky but it works for now.

Edit:

Also another hint from Eli H. that if you're logging within the interrupt context you will, for sure, drop data if CONFIG_LOG_MODE_IMMEDIATE is set to 'y'. Either turn of immediate logging or remove logging from the ISR and you should be good to go!

RE: UARTE communication using CONFIG_UART_INTERRUPT_DRIVEN dropping data after 8 bytes

Jared — Wed, 26 Aug 2020 21:57:54 GMT

Hey Jonathan,

I was able to try your suggestion here. Here's my code looks like:

static uint8_t buf[256];

static void uart_cb(struct device *dev)
{

  uart_irq_update(dev);

  /* Read as much data as possible */
  if (uart_irq_rx_ready(dev))
  {
    /* Read operation and get bytes read*/
    int len = uart_fifo_read(dev, buf, 256);

    LOG_INF("%d bytes", len);
  }

  if (uart_irq_tx_ready(dev))
  {
    /* Release last buf */

    /* Get next */
  }
}

int comms_init(comms_evt_callback_t cb)
{
  if (cb == NULL)
  {
    return -EINVAL;
  }

  /* Copy pointer to callback */
  callback = cb;

  /* Get the UART device */
  uart = device_get_binding(DT_LABEL(DT_NODELABEL(uart2)));
  if (!uart)
  {
    return -ENXIO;
  }

  /* Enable ISR */
  uart_irq_callback_set(uart, uart_cb);

  /* Enable RX events */
  uart_irq_rx_enable(uart);

  /* Enable the thread */
  k_sem_give(&comms_init_ok);

  return 0;
}

It's extremely similar compared to the example you sent. Unfortunately it's still receiving only single bytes. Here's the debug printout showing I only got 12 bytes out of the 30+ bytes sent on the other end.

1 bytes
1 bytes
1 bytes
1 bytes
1 bytes
1 bytes
1 bytes
1 bytes
1 bytes
1 bytes
1 bytes
1 bytes

RE: UARTE communication using CONFIG_UART_INTERRUPT_DRIVEN dropping data after 8 bytes

Jared — Wed, 26 Aug 2020 15:01:38 GMT

Thanks Jonathan!

I will try exactly that and let you know. I think the biggest difference in mine was that I was trying to read byte by byte. I found that code elsewhere in NCS. Must have been for a different purpose!

RE: UARTE communication using CONFIG_UART_INTERRUPT_DRIVEN dropping data after 8 bytes

JONATHAN LL — Wed, 26 Aug 2020 13:59:37 GMT

Hi, I might have misunderstood you original problem.

I see that you are using a uart_cb function not implemented as a nrf9160 example yet so I would recommend to look at this example.
Could you se if the same behavior persists using the example implementation?
I have not tested to see if there is a 8 byte internal buffer or tested to se if it the buffer is configurable at this moment.

Regards,
Jonathan

RE: UARTE communication using CONFIG_UART_INTERRUPT_DRIVEN dropping data after 8 bytes

Jared — Tue, 25 Aug 2020 15:27:51 GMT

Hey Jonathan,

Thanks for the tip. I'm not sure how it relates though.

This seems to be an issue related to the UART implementation unless Im missing something huge here. If I simply print out the bytes from the ISR, it prints the first 8 and then stops. Seems like there's an internal 8 byte buffer. Anything after that 8 bytes gets dropped as far as I can tell.

RE: UARTE communication using CONFIG_UART_INTERRUPT_DRIVEN dropping data after 8 bytes

JONATHAN LL — Tue, 25 Aug 2020 14:28:35 GMT

Hi Jared,

Check out Ring buffers, https://docs.zephyrproject.org/latest/reference/kernel/other/ring_buffers.html#implementation

Regards,
Jonathan

RE: UARTE communication using CONFIG_UART_INTERRUPT_DRIVEN dropping data after 8 bytes

Jared — Mon, 24 Aug 2020 20:49:04 GMT

While this is good for many cases, it doesn't quite work for my use case. I'd like to read byte by byte as I have variable payloads. Any thoughts here would be great!

RE: UARTE communication using CONFIG_UART_INTERRUPT_DRIVEN dropping data after 8 bytes

Jared — Sat, 15 Aug 2020 02:07:42 GMT

Appears to be fixed with ASYNC. I used the code in the peripheral_uart example. Github Link

I'm using flow control so here's my final prj.conf

# Enable the UART driver
CONFIG_UART_ASYNC_API=y
CONFIG_UART_LINE_CTRL=y
CONFIG_NRFX_UARTE2=y
CONFIG_SERIAL=y