Weird behavior of HAL_UARTEx_RxEventCallback()

[Beppe101]

Hi all,

I setup DMA normal mode, on RS485 port where I receive more or less 1 byte per second.
Also, I have DMA normal mode on a debug serial port.

I want to send back on rs485 the characters I receive on that port.
What I observe is that if I add the following printf(), that redirects output to debug UART, in HAL_UARTEx_RxEventCallback()
printf( "errCode=%i\r\n", retCode );
everyting works fine, with TeraTerm software, I can see the characters I input in RS485 window displayed correctly.
BUT, if I remove the printf(), when I press keys in rs485 window the cursor only moves one space to the right not showing any character.
Also, if I set a breakpoint at the begiining of HAL_UARTEx_RxEventCallback(), it only gets called once on the first character I type in rs485 putty window and the sending back of the character received is ok, but then on subsequent pressing of keys HAL_UARTEx_RxEventCallback() is never called and nothing is shown in TeraTerm window.

I'm using STM32G070RBTx, STM32CubeIDE v. 1.13.2, I can't figure out what is going on, please help.

/* USER CODE BEGIN Header */
/**
 ******************************************************************************
 * @file           : main.c
 * @brief          : Main program body
 ******************************************************************************
 * @attention
 *
 * Copyright (c) 2023 STMicroelectronics.
 * All rights reserved.
 *
 * This software is licensed under terms that can be found in the LICENSE file
 * in the root directory of this software component.
 * If no LICENSE file comes with this software, it is provided AS-IS.
 *
 ******************************************************************************
 */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "adc.h"
#include "crc.h"
#include "dma.h"
#include "tim.h"
#include "usart.h"
#include "gpio.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include <stdio.h>
#include <string.h>
#include "Serials.h"
#include "SerialDebug.h"
#include "AGC.h"
#include "RingBuffer.h"


/* USER CODE END Includes */

/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)
/* USER CODE END PTD */

/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */

/* USER CODE END PD */

/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */

/* USER CODE END PM */

/* Private variables ---------------------------------------------------------*/

/* USER CODE BEGIN PV */

/**************************************
 *  Global variables                  *
 **************************************/

/* The device number id */
uint8_t deviceNumber = 0;

/* The array of ADC1 channels converted values */
uint16_t ADC1Values[ADC1_NUMBER_OF_CHANNELS];

/* The error code from parse operation */
ParseErrorCode_t parseResult;
/* The command received via debug serial port */
ParsedCommand_t cmd;

/* Serial port inbound ring buffer */
RingBuffer_t debugSerialInboundBuffer;
/* Serial port outbound ring bufer */
RingBuffer_t debugSerialOutboundBuffer;

/* Debug serial port inbound data buffer for inbound RingBuffer */
unsigned char * debugSerialInboundData[debugSerialInboundBufferSize];
/* Debug serial port outbound data buffer for outbound ringbuffer */
unsigned char * debugSerialOutboundData[debugSerialOutboundBufferSize];
/* Debug serial port inbound data buffer entry */
unsigned char debugSerialInboundEntry[debugSerialInboundBufferEntrySize];
/* Debug serial port outbound data buffer entry */
unsigned char debugSerialOutboundEntry[debugSerialOutboundBufferEntrySize];

/* Inbound buffer lost messages count */
int debugSerialInboundLostMessagesCount = 0;
/* Outbound buffer lost messages count */
int debugSerialOutboundLostMessagesCount = 0;

extern uint8_t UART2_charRxBuffer;

/* ADC1 converted values */
uint16_t ADC1Values[ADC1_NUMBER_OF_CHANNELS];

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP */


#define PUTCHAR_PROTOTYPE int __io_putchar(int ch)


/**
  * @brief  Retargets the C library printf function to the USART.
  *   None
  * @retval None
  */
PUTCHAR_PROTOTYPE
{
  /* Place your implementation of fputc here */
  /* e.g. write a character to the USART1 and Loop until the end of transmission */
  HAL_UART_Transmit(&huart2, (uint8_t *)&ch, 1, 0xFFFF);

  return ch;
}



/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
const uint8_t rs485SerialInboundBufferEntrySize = 255;

/* RS485 serial port inbound data buffer entry */
//unsigned char rs485SerialInboundEntry[rs485SerialInboundBufferEntrySize];

extern DMA_HandleTypeDef hdma_usart1_rx;

#define rs485SerialInboundBufferEntrySize 255
unsigned char rs485SerialInboundEntry[rs485SerialInboundBufferEntrySize];

/* USER CODE END 0 */

/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */
    int returnCode = 0;
    /* Initialize debug serial inbound buffer */
    ringBufferInit( &debugSerialInboundBuffer, debugSerialInboundData, debugSerialInboundBufferSize );
    /* Initialize debug serial outbound buffer */
    ringBufferInit( &debugSerialOutboundBuffer, debugSerialOutboundData, debugSerialOutboundBufferSize );

  /* USER CODE END 1 */

  /* MCU Configuration--------------------------------------------------------*/

  /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  HAL_Init();

  /* USER CODE BEGIN Init */


  /* USER CODE END Init */

  /* Configure the system clock */
  SystemClock_Config();

  /* USER CODE BEGIN SysInit */

  /* USER CODE END SysInit */

  /* Initialize all configured peripherals */
  MX_GPIO_Init();
  MX_DMA_Init();
  MX_USART2_UART_Init();
  MX_TIM6_Init();
  MX_ADC1_Init();
  MX_TIM14_Init();
  MX_USART1_UART_Init();
  MX_CRC_Init();
  MX_TIM3_Init();
  /* USER CODE BEGIN 2 */

  extern DMA_HandleTypeDef hdma_usart2_rx;

    /* Start conversion of ADC1 channels values in DMA mode */
    HAL_ADC_Start_DMA( &hadc1, (uint32_t *)ADC1Values, ADC1_NUMBER_OF_CHANNELS );
    /* Start reception of characters from debug serial port in DMA mode */
    HAL_UART_Receive_DMA( &huart2, &UART2_charRxBuffer, 1 );

    /* Disable the half transfer complete of data in DMA interrupt mode */
    __HAL_DMA_DISABLE_IT(&hdma_usart2_rx, DMA_IT_HT);
    /* Enable the transfer complete of data in DMA interrupt mode */
    __HAL_DMA_ENABLE_IT(&hdma_usart2_rx, DMA_IT_TC);

    HAL_UARTEx_ReceiveToIdle_DMA( &huart1, rs485SerialInboundEntry, rs485SerialInboundBufferEntrySize );
    /* Disable the half transfer complete of data in DMA interrupt mode */
    __HAL_DMA_DISABLE_IT(&hdma_usart1_rx, DMA_IT_HT);
    /* Enable the transfer complete of data in DMA interrupt mode */
    __HAL_DMA_ENABLE_IT(&hdma_usart1_rx, DMA_IT_TC);



    HAL_TIM_Base_Start_IT(&htim6);
    HAL_TIM_Base_Start_IT(&htim3);
    HAL_TIM_IC_Start_IT(&htim3, TIM_CHANNEL_1);
    HAL_TIM_IC_Start_IT(&htim3, TIM_CHANNEL_2);

    HAL_TIM_PWM_Start(&htim14, TIM_CHANNEL_1);
    HAL_TIM_Base_Start(&htim14);

    HAL_UART_MspInit(&huart1);
    HAL_UART_MspInit(&huart2);

    __HAL_RCC_CRC_CLK_ENABLE();

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */

    while (1) {

        /* Manage incoming message on the RS485 serial port */


    	/* Manage outcoming message on the RS485 serial port */



        /* Manage incoming message on the debug serial port */
    	if ( !ringBufferRead( &debugSerialInboundBuffer, debugSerialInboundEntry ) )
    	{
            /* Parse the user command */
            parseResult = parseDebugCommand( debugSerialInboundEntry, &cmd );  // check return code

            /* Execute user command */
            executeDebugCommand( &cmd );
    	}

    	/* Manage outcoming message on the debug serial port */

    	if ( !ringBufferRead( &debugSerialOutboundBuffer, debugSerialOutboundEntry ) )
    	{
            /* Wait for previous transmission to complete */
            while ( __HAL_UART_GET_FLAG(&huart2, UART_FLAG_TC) != SET ) {};
            /* Send outbound message */
            HAL_UART_Transmit_DMA( &huart2, debugSerialOutboundEntry, (uint16_t)strlen( (char *)debugSerialOutboundEntry ) );
    	}

    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
	}
  /* USER CODE END 3 */
}

void HAL_UARTEx_RxEventCallback(UART_HandleTypeDef *huart, uint16_t Size)
{
	int retCode = 0;

	if (huart->Instance == USART1)
	{
		while ( __HAL_UART_GET_FLAG(&huart1, UART_FLAG_TC) != SET ) {};

        /* Pull DE high to enable TX operation */
        HAL_GPIO_WritePin (USART1_DE_GPIO_Port, USART1_DE_Pin, GPIO_PIN_SET);

        sprintf( &rs485SerialInboundEntry[Size], "\r\n\0" );

		 retCode = HAL_UART_Transmit_DMA(&huart1, rs485SerialInboundEntry, strlen( rs485SerialInboundEntry ) );
		 printf( "errCode=%i\r\n", retCode );

         /* Pull DE low to enable RX operation */
         HAL_GPIO_WritePin (USART1_DE_GPIO_Port, USART1_DE_Pin, GPIO_PIN_RESET);

         retCode = HAL_UARTEx_ReceiveToIdle_DMA( &huart1, rs485SerialInboundEntry, rs485SerialInboundBufferEntrySize );

		 /* Disable the half transfer complete of data in DMA interrupt mode */
		 __HAL_DMA_DISABLE_IT(&hdma_usart1_rx, DMA_IT_HT);
		 /* Enable the transfer complete of data in DMA interrupt mode */
		  __HAL_DMA_ENABLE_IT(&hdma_usart1_rx, DMA_IT_TC);

	}
}
/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

  /** Configure the main internal regulator output voltage
  */
  HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1);

  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSIDiv = RCC_HSI_DIV1;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  RCC_OscInitStruct.PLL.PLLM = RCC_PLLM_DIV1;
  RCC_OscInitStruct.PLL.PLLN = 8;
  RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
  RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }

  /** Initializes the CPU, AHB and APB buses clocks
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
}

/* USER CODE BEGIN 4 */

/* USER CODE END 4 */

/**
  * @brief  This function is executed in case of error occurrence.
  * @retval None
  */
void Error_Handler(void)
{
  /* USER CODE BEGIN Error_Handler_Debug */
	/* User can add his own implementation to report the HAL error return state */
	__disable_irq();
	while (1) {
	}
  /* USER CODE END Error_Handler_Debug */
}

#ifdef  USE_FULL_ASSERT
/**
  * @brief  Reports the name of the source file and the source line number
  *         where the assert_param error has occurred.
  *   file: pointer to the source file name
  *   line: assert_param error line source number
  * @retval None
  */
void assert_failed(uint8_t *file, uint32_t line)
{
  /* USER CODE BEGIN 6 */
	/* User can add his own implementation to report the file name and line number,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

[TDK]

Using blocking functions (HAL_UART_Transmit, via printf) inside HAL_UARTEx_RxEventCallback, particular before you restart the reception again, could be causing overflow events which will stop UART from working until you clear those errors.

[Beppe101 · Accepted solution]

This is how i solved it:

- Added in HAL_UARTEx_RxEventCallback()

while ( __HAL_UART_GET_FLAG(&huart1, UART_FLAG_TC) != SET ) {};

to wait transmission completion before setting and resetting the DE pin.

- Enabled DMA recepion with HAL_UARTEx_ReceiveToIdle_DMA() after resetting the DE pin. ( DMA is in normal mode ).

- Do not use the same data buffer for HAL_UARTEx_ReceiveToIdle_DMA() and HAL_UART_Transmit_DMA().

And now works great.

Thanks TDK for encouragement.