HAL_UART_Receive versus HAL_UART_Receive_IT

mvonahnen · ‎2017-02-06

Posted on February 06, 2017 at 21:21

I am using a Nucleo-L476RG board and I am trying to use the HAL_UART_Receive_IT function to receive a byte at a time from a RS-232 source (4800 Baud) on UART 4. I need to use the interrupt because I am transmitting out on UART3 console data and I miss characters when I transmit long strings. But I always get a framing error when I call the my receive function:

UART4_status = HAL_UART_Receive_IT(&huart4,(uint8_t *)rx_data, 1);

I don't see any framing errors when I poll for the data:

UART4_status = HAL_UART_Receive(&huart4,(

uint8_t

*)rx_data, 1, 1000);

Here the initialization of the UART generated by CubeMX:

/* UART4

init

function */

static

void

MX_UART4_Init(

void

)

{

huart4.

Instance

= UART4;

huart4.

Init

.

BaudRate

= 4800;

huart4.

Init

.

WordLength

= UART_WORDLENGTH_8B;

huart4.

Init

.

StopBits

= UART_STOPBITS_1;

huart4.

Init

.

Parity

= UART_PARITY_NONE;

huart4.

Init

.

Mode

= UART_MODE_TX_RX;

huart4.

Init

.

HwFlowCtl

= UART_HWCONTROL_NONE;

huart4.

Init

.

OverSampling

= UART_OVERSAMPLING_16;

huart4.

Init

.

OneBitSampling

= UART_ONE_BIT_SAMPLE_DISABLE;

huart4.

AdvancedInit

.

AdvFeatureInit

= UART_ADVFEATURE_NO_INIT;

if

(HAL_UART_Init(&huart4) !=

HAL_OK

)

{

Error_Handler();

}

Before I try to receive data, I enable the RXNE interrupt:

__HAL_UART_CLEAR_OREFLAG(&huart4);

__HAL_UART_ENABLE_IT(&huart4, UART_IT_RXNE);

I have attached the main.c.

Is there something I am missing on the interrupt initialization?

T J · ‎2017-02-06

Posted on February 06, 2017 at 21:54

Are you using RS485 half duplex ?

this works very well for TX with DMA

void CheckTxDMABufferProgress(void){ if ( DMABufHasData ){ char uartState = HAL_UART_GetState(&huart1); if ((uartState == HAL_UART_STATE_READY) || (uartState == HAL_UART_STATE_BUSY_RX)) { DMABufHasData = false; // sending now if (HAL_UART_Transmit_DMA(&huart1, (uint8_t *)Usart1TxDMABuffer + U1TxBufferPtrOUT ,U1TxBufferPtrIN - U1TxBufferPtrOUT) == HAL_OK){ HAL_UART_Transmit_DMA_Status = UartDMAsuccess; U1TxBufferPtrOUT = U1TxBufferPtrIN; } else{ Error_Handler(); /* Transfer error in transmission process */ HAL_UART_Transmit_DMA_Status = UartDMAfailed; } } }}�?�?�?�?�?�?�?

Andrei Chichak · ‎2017-02-06

Posted on February 06, 2017 at 22:02

This might be useful:

http://embedded.fm/blog/2016/11/29/discovery-uarts-part-1

http://embedded.fm/blog/2016/12/6/discovery-uarts-part-2-connections

http://embedded.fm/blog/2016/12/13/discovery-uarts-part-3-the-final-step

mvonahnen · ‎2017-02-06

Posted on February 06, 2017 at 22:10

Thanks but I did not see any references to the interrupt routines in these web pages. If you saw something in particular that might help could you indicate it?

Abhishek Kumar · ‎2017-11-04

Posted on November 04, 2017 at 22:44

I am also facing the same problem, do u have the solution?

Joerg Wagner · ‎2017-11-04

Posted on November 05, 2017 at 01:24

Hello.

Did you read the User Manual of the HAL drivers?

Receive an amount of data in non blocking mode using HAL_UART_Receive_IT().

At reception end of transfer HAL_UART_RxCpltCallback is executed and user can

add his own code by customization of function pointer HAL_UART_RxCpltCallback.

Your intention is to use the interrupt mechanism but you use a poll function to read.

Instead, define the Callback function i.e.:

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)

{

if (huart==&huart4) {

// do something with rx_data

HAL_UART_Receive_IT(&huart4, &rx_data, 1); // trigger the next read

}

and call it once in main():

HAL_UART_Receive_IT(&huart4, &rx_data, 1);

Everytime a character is available the callback function is called automatically.

diverger · ‎2018-04-17

Posted on April 17, 2018 at 15:16

Are you sure that we need place another â€œ

HAL_UART_Receive_IT

â€� in the callback function? I don't see them in the examples given by ST.

Huzaifah Limbada · ‎2018-04-17

Posted on April 18, 2018 at 08:55

To receive full string as you transfer you have to made changes into the register level code...here i have mention in which function or you can just do copy and paste with that function.

static HAL_StatusTypeDef UART_Receive_IT(UART_HandleTypeDef *huart)

{

uint16_t uhMask = huart->Mask;

uint16_t uhdata;

/* Check that a Rx process is ongoing */

if(huart->RxState == HAL_UART_STATE_BUSY_RX)

{

uhdata = (uint16_t) READ_REG(huart->Instance->RDR);

*huart->pRxBuffPtr++ = (uint8_t)(uhdata & (uint8_t)uhMask);

HAL_UART_RxCpltCallback(huart);

return HAL_OK;

}

else

{

/* Clear RXNE interrupt flag */

__HAL_UART_SEND_REQ(huart, UART_RXDATA_FLUSH_REQUEST);

return HAL_BUSY;

}

You can find this function in to the 'stm32l0xx_hal_uart.c'

Hope you'll get your solution by this!!!

Joerg Wagner · ‎2018-04-19

Posted on April 19, 2018 at 23:49

Are there examples not just turning on a LED?