topic The usage of UART callback function install in Kinetis Software Development Kit

The usage of UART callback function install

ConstYu — Fri, 24 Jul 2015 02:58:02 GMT

I am running the uart_blocking_example in C:\Freescale\KSDK_1.2.0\examples\frdmk22f\driver_examples\uart\uart_blocking\iar, it can runs well, after adding the UART_DRV_InstallTxCallback function like below code, it blocked the UART output. so i wonder the usage of UART callback function, is there any example?

// Initialize the uart module with base address and config structure

UART_DRV_Init(BOARD_DEBUG_UART_INSTANCE, &uartState, &uartConfig);

UART_DRV_InstallTxCallback(uint32_t instance, (uart_tx_callback_t) callback, NULL, NULL);

// Inform to start blocking example

byteCountBuff = sizeof(buffStart);

UART_DRV_SendDataBlocking(BOARD_DEBUG_UART_INSTANCE, buffStart, byteCountBuff, 1000u);

Re: The usage of UART callback function install

xiangjun_rong — Tue, 28 Jul 2015 02:47:03 GMT

Hi, NingNing,

I have developed an example based on the example the SDK provides:

D:\Freescale\KSDK_1.2.0\examples\frdmk22f\driver_examples\uart\uart_non_blocking, I have changed the main.c to test the call back function, the callback function works well.

I attach the main.c function. Hope it can help you.

Xiangjun rong

Re: The usage of UART callback function install

ConstYu — Wed, 29 Jul 2015 16:07:23 GMT

Hi Xiangjun,

Thanks for your reply, i test the code you send me, but found it always output "K" after install the callback function, the callback function should only output one char "K" at one time, i also only do count++ in the call back, but found it will not stop to call the callback, it never to stop. My another colleague also encounter this issue.

So i dive into the driver layer code carefully, found it would be one bug in driver lay, it needs to add the two line red code, as below is the code in TX interrupt in fsl_uart_driver.c, if i install the TX callback function by UART_DRV_InstallTxCallback function, the code will never move the position of TXbuffer and transfer byte numbers, so it lead to never to call UART_DRV_CompleteSendData(instance);

Now after i add these two line, the code can work as expected. do you think so? (one remainder, don't forget to build the lib after you change the fsl_uart_driver.c file)

if((UART_BRD_C2_TIE(base)) && (UART_BRD_S1_TDRE(base)))

{

/* Check to see if there are any more bytes to send */

if (uartState->txSize)

{

uint8_t emptyEntryCountInFifo;

#if FSL_FEATURE_UART_HAS_FIFO

emptyEntryCountInFifo = uartState->txFifoEntryCount -

UART_HAL_GetTxDatawordCountInFifo(base);

#else

emptyEntryCountInFifo = uartState->txFifoEntryCount;

#endif

while(emptyEntryCountInFifo--)

{

/* Transmit data and update tx size/buff */

UART_HAL_Putchar(base, *(uartState->txBuff));

/* Invoke callback if there is one */

if (uartState->txCallback != NULL)

{

/* The callback MUST set the txSize to 0 if the

* transmit is ended.*/

uartState->txCallback(instance, uartState);

++uartState->txBuff;

--uartState->txSize;

}

else

{

++uartState->txBuff;

--uartState->txSize;

}

/* Check and see if this was the last byte */

if (uartState->txSize == 0U)

{

UART_DRV_CompleteSendData(instance);

break;

}

Re: The usage of UART callback function install

xiangjun_rong — Fri, 31 Jul 2015 10:35:17 GMT

Hi, NingNing,

I think your modification is okay. whether the driver is okay or not is dependent on how to define the task of the callback function. Generally, the callback function is called in the interrupt service routine of the UART transmitter. After the UART module has completed to transfer a char, the interrupt service routine of the UART transmitter is executed once, of course, the callback function is executed once.

xiangjun Rong

Re: The usage of UART callback function install

Elieser — Fri, 10 Sep 2021 19:00:01 GMT

Thanks, you helped me a lot for this!!