LIBUARTE RX Buffer Full event

RE: LIBUARTE RX Buffer Full event

ogulcan — Wed, 23 Feb 2022 13:45:46 GMT

Hi,

I was having a similar problem with the LIBUARTE library. In the end I realised that there is a way to understand if the event is because of a full buffer or timeout. The variable p_libuarte->p_ctrl_blk->sub_rx_count is always 0 if the event is coming from a full buffer.

Here is my uartEventHandle if anyone else needs it:

/**@brief Function for handling UARTE callback events.
 *
 * @param[in]   context   Pointer to UARTE library asynhronous instance.
 * @param[in]   p_evt     Pointer to UARTE library asynhronous event.
 */
static void uartEventHandle(void * context, nrf_libuarte_async_evt_t * p_evt)
{
    /* Holds pointer to UARTE library instance. */
    nrf_libuarte_async_t * p_libuarte = (nrf_libuarte_async_t *)context;
    /* Holds yield request. */
    BaseType_t yieldReq = pdFALSE;
    /* Decide according to event type. */
    switch(p_evt->type)
    {
        case NRF_LIBUARTE_ASYNC_EVT_RX_DATA:
            /* Check if buffer full event. */
            if(0 == p_libuarte->p_ctrl_blk->sub_rx_count)
            {
                /* Copy new data to buffer but wait for the second event. */
            }
            else
            {
                /* Copy rest of data to your buffer and notify the task to process it. */   
                vTaskNotifyGiveFromISR(taskHandle, &yieldReq);
                portYIELD_FROM_ISR(yieldReq);
            }
            /* Free UARTE memory. */
            nrf_libuarte_async_rx_free(p_libuarte, p_evt->data.rxtx.p_data, \
                                       p_evt->data.rxtx.length);
            break;
        case NRF_LIBUARTE_ASYNC_EVT_ERROR:
            break;
        case NRF_LIBUARTE_ASYNC_EVT_TX_DONE:
            break;
        default:
            break;
    }
}

So there is no need to change the files from the SDK.

RE: LIBUARTE RX Buffer Full event

vlockhead — Fri, 21 Jan 2022 16:15:31 GMT

Thank you for your answer Edvin! I will look into implementing the buffer full event.

RE: LIBUARTE RX Buffer Full event

Edvin — Thu, 20 Jan 2022 14:13:51 GMT

Hello,

There is no way to tell from the uart_event_handler() in main.c (looking at the SDK\examples\peripheral\libuarte example) to tell what generated the NRF_LIBUARTE_ASYNC_EVT_RX_DATA event. If you want to separate on the two cases where the buffer is full and the timeout, I guess I would've tried adding a parameter saying what generated the event in nrf_libuarte_async.c.

As you can tell, it is either line 243 or 321 that generate the NRF_LIBUARTE_ASYNC_EVT_RX_DATA event. Try adding this to the nrf_libuarte_async_evt_t:

typedef struct
{
    nrf_libuarte_async_evt_type_t type; ///< Event type.
    union {
        nrf_libuarte_async_data_t rxtx;                   ///< RXD/TXD data.
        uint8_t                   errorsrc;               ///< Error source.
        nrf_libuarte_async_overrun_err_evt_t overrun_err; ///< Overrun error data.
        uint8_t                   src;                    ///< what triggered the event  <- add this line
    } data;                                 ///< Union with data.
} nrf_libuarte_async_evt_t;

And then in the nrf_libuarte_async.c use this parameter to say whether the event was triggered by a timeout or a buffer that is full. E.g by setting it to 0 when the buffer was full or 1 when the timeout occured:

    case NRF_LIBUARTE_DRV_EVT_RX_DATA:
    {

        uint32_t rx_amount = p_evt->data.rxtx.length - p_libuarte->p_ctrl_blk->sub_rx_count;
        if (rx_amount)
        {
            p_libuarte->p_ctrl_blk->rx_count += rx_amount;
            nrf_libuarte_async_evt_t evt = {
                .type = NRF_LIBUARTE_ASYNC_EVT_RX_DATA,
                .data = {
                    .rxtx = {
                        .p_data = &p_evt->data.rxtx.p_data[p_libuarte->p_ctrl_blk->sub_rx_count],
                        .length = rx_amount,
                        .src = 0
                    }
                }
            };
            
            
...
void nrf_libuarte_async_timeout_handler(const nrf_libuarte_async_t * p_libuarte)
{
    NRFX_IRQ_DISABLE((IRQn_Type)NRFX_IRQ_NUMBER_GET(p_libuarte->p_libuarte->uarte));

    uint32_t capt_rx_count = p_libuarte->p_libuarte->timer.p_reg->CC[3];

    if (capt_rx_count > p_libuarte->p_ctrl_blk->rx_count)
    {
        uint32_t rx_amount = capt_rx_count - p_libuarte->p_ctrl_blk->rx_count;
        nrf_libuarte_async_evt_t evt = {
            .type = NRF_LIBUARTE_ASYNC_EVT_RX_DATA,
            .data = {
                .rxtx = {
                    .p_data = &p_libuarte->p_ctrl_blk->p_curr_rx_buf[p_libuarte->p_ctrl_blk->sub_rx_count],
                    .length = rx_amount,
                    .src = 1,
                }
            }

This way you can tell from main.c where the event is coming from:

...

case NRF_LIBUARTE_ASYNC_EVT_RX_DATA:
            if (p_evt->data.src == 0)
            {
                NRF_LOG_INFO("triggered by full buffer");
            }
            else if (p_evt->data.src == 1)
            {
                NRF_LOG_INFO("Triggered by timeout");
            }
            ret = nrf_libuarte_async_tx(p_libuarte,p_evt->data.rxtx.p_data, p_evt->data.rxtx.length);
            if (ret == NRF_ERROR_BUSY)
            {
                buffer_t buf = {
                    .p_data = p_evt->data.rxtx.p_data,
                    .length = p_evt->data.rxtx.length,
                };

                ret = nrf_queue_push(&m_buf_queue, &buf);
                APP_ERROR_CHECK(ret);
            }

...

And if you want it to be fancy, you can create an enum instead of using the "0" and "1".

That is correct.

That is not the way it is done in the libuarte library. You can use the above workaround to just copy the data if the event was caused by a full buffer, and attach the last part of the message from the timeout later before you process the data, or you can look into implementing a ring buffer. There is no simple way to make libuarte use a ring buffer out of the box, unfortunately.

Best regards,

Edvin

RE: LIBUARTE RX Buffer Full event

vlockhead — Wed, 19 Jan 2022 19:23:24 GMT

There is the same question here: https://devzone.nordicsemi.com/f/nordic-q-a/81200/libuarte-packet-fragmentation/337220#337220

But no obvious fix