UART receive interrupt callback completing receive

adyr — Wed, 30 Sep 2015 11:50:06 GMT

Hi,

I am using KSDK 1.2 and KDS 3.0 with the IAR compiler. I have added a UART component and ticked the box to install the receive interrupt.

What I want to do is terminate the blocking receive when a EOT is received (packet based reception). However the interrupt callback has now way to end the reception. The current loop in the UART_DRV_IRQHandler is as follows:

#if FSL_FEATURE_UART_HAS_FIFO
        /* Read out all data from RX FIFO */
        while(UART_HAL_GetRxDatawordCountInFifo(base))
        {
#endif
            /* Get data and put into receive buffer */
            UART_HAL_Getchar(base, uartState->rxBuff);

            /* Invoke callback if there is one */
            if (uartState->rxCallback != NULL)
            {
                uartState->rxCallback(instance, uartState);
            }
            else
            {
                ++uartState->rxBuff;
                --uartState->rxSize;

                /* Check and see if this was the last byte */
                if (uartState->rxSize == 0U)
                {
                    UART_DRV_CompleteReceiveData(instance);
                    #if FSL_FEATURE_UART_HAS_FIFO
                    break;
                    #endif
                }
            }
#if FSL_FEATURE_UART_HAS_FIFO
        }
#endif

If I change the inner part of loop to:

   /* Check and see if this was the last byte */
   if (uartState->rxSize == 0U)
   {
    UART_DRV_CompleteReceiveData(instance);
    #if FSL_FEATURE_UART_HAS_FIFO
    break;
    #endif
   }

Then the user interrupt call back can terminate the reception by setting uartState->rxSize to 0.

I was wondering if Freescale would consider making this change to future KSDK versions so I don't have to modify the KSDK code?

Best regards,

Adrian.

Re: UART receive interrupt callback completing receive

adyr — Wed, 30 Sep 2015 14:42:09 GMT

OK. More testing has found that my change breaks the nio_serial as that almost uses the fsl_uart_driver but it does not setup uartState->rxSize. It prefers to do it's own thing which is possibly why the Rx loop is different to the Tx loop.

If I change the:

if (uartState->rxSize == 0U)

if (uartState->isRxBlocking && (uartState->rxSize == 0U))

Then both are happy as nio_serial does not set the blocking flag either.

Re: UART receive interrupt callback completing receive

Jorge_Gonzalez — Mon, 05 Oct 2015 23:12:37 GMT

Hello Adrian Rockall:

Thank you for your feedback.

This issue has been reported internally (ticket KPSDK-5144).

The proper modifications could not make it into KSDK v1.3, but a change of the UART driver and callback scheme is planned to avoid these issues in the next version of KSDK.

Regards!

Jorge Gonzalez

topic UART receive interrupt callback completing receive in Kinetis Software Development Kit

UART receive interrupt callback completing receive

Re: UART receive interrupt callback completing receive

Re: UART receive interrupt callback completing receive