UART interrupt not working properly on STM32H753 MCU?

[Akash_k]

I am using STM32H753 MCU. I generated my code using STM32Cube. The UART is configured to work on interrupt, baud rate is 19200. I sent 'A' many time but most of the time I am receiving "C1" in hex instead of "41" ('A' in ASCII).

When I analyzed the data i found that I was receiving C instead of 4, B instead of 3, E instead of 6, F instead of 7. Most of the times I was receiving wrong data.

int main(void)
{
  HAL_Init();
 
HAL_Delay(2000); 
 
 SystemClock_Config();
HAL_Delay(2000); 
 
 MX_GPIO_Init();
HAL_Delay(2000); 
 
MX_USART1_UART_Init();
HAL_Delay(2000); 
 
  HAL_UART_Receive_IT(&huart1,recbuf,80);
 
  while (1)
  {
		if(rec_data == 1)
		{
			rec_data = 0;
			
			//sprintf(recbuf, "RECEIVED");
			//HAL_UART_Transmit_IT(&huart1,recbuf,9);
		}
  }
}
 
 
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInitStruct = {0};
 
  /** Supply configuration update enable 
  */
  HAL_PWREx_ConfigSupply(PWR_LDO_SUPPLY);
  /** Configure the main internal regulator output voltage 
  */
  __HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE3);
 
  while(!__HAL_PWR_GET_FLAG(PWR_FLAG_VOSRDY)) {}
  /** Macro to configure the PLL clock source 
  */
  __HAL_RCC_PLL_PLLSOURCE_CONFIG(RCC_PLLSOURCE_HSI);
  /** Initializes the CPU, AHB and APB busses clocks 
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_DIV1;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
  if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
  /** Initializes the CPU, AHB and APB busses clocks 
  */
  RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK|RCC_CLOCKTYPE_SYSCLK
                              |RCC_CLOCKTYPE_PCLK1|RCC_CLOCKTYPE_PCLK2
                              |RCC_CLOCKTYPE_D3PCLK1|RCC_CLOCKTYPE_D1PCLK1;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_HSI;
  RCC_ClkInitStruct.SYSCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB3CLKDivider = RCC_APB3_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_APB1_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_APB2_DIV1;
  RCC_ClkInitStruct.APB4CLKDivider = RCC_APB4_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
  PeriphClkInitStruct.PeriphClockSelection = RCC_PERIPHCLK_USART1|RCC_PERIPHCLK_ADC
                              |RCC_PERIPHCLK_I2C1;
  PeriphClkInitStruct.PLL2.PLL2M = 32;
  PeriphClkInitStruct.PLL2.PLL2N = 129;
  PeriphClkInitStruct.PLL2.PLL2P = 2;
  PeriphClkInitStruct.PLL2.PLL2Q = 2;
  PeriphClkInitStruct.PLL2.PLL2R = 2;
  PeriphClkInitStruct.PLL2.PLL2RGE = RCC_PLL2VCIRANGE_1;
  PeriphClkInitStruct.PLL2.PLL2VCOSEL = RCC_PLL2VCOWIDE;
  PeriphClkInitStruct.PLL2.PLL2FRACN = 0;
  PeriphClkInitStruct.Usart16ClockSelection = RCC_USART16CLKSOURCE_D2PCLK2;
  PeriphClkInitStruct.I2c123ClockSelection = RCC_I2C123CLKSOURCE_D2PCLK1;
  PeriphClkInitStruct.AdcClockSelection = RCC_ADCCLKSOURCE_PLL2;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInitStruct) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief ADC1 Initialization Function
  * @param None
  * @retval None
  */
static void MX_ADC1_Init(void)
{ 
  ADC_MultiModeTypeDef multimode = {0};
  ADC_ChannelConfTypeDef sConfig = {0};
 
 
  hadc1.Instance = ADC1;
  hadc1.Init.ClockPrescaler = ADC_CLOCK_ASYNC_DIV1;
  hadc1.Init.Resolution = ADC_RESOLUTION_16B;
  hadc1.Init.ScanConvMode = ADC_SCAN_DISABLE;
  hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
  hadc1.Init.LowPowerAutoWait = DISABLE;
  hadc1.Init.ContinuousConvMode = DISABLE;
  hadc1.Init.NbrOfConversion = 1;
  hadc1.Init.DiscontinuousConvMode = DISABLE;
  hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
  hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
  hadc1.Init.ConversionDataManagement = ADC_CONVERSIONDATA_DR;
  hadc1.Init.Overrun = ADC_OVR_DATA_PRESERVED;
  hadc1.Init.LeftBitShift = ADC_LEFTBITSHIFT_NONE;
  hadc1.Init.OversamplingMode = DISABLE;
  if (HAL_ADC_Init(&hadc1) != HAL_OK)
  {
    Error_Handler();
  }
 
  multimode.Mode = ADC_MODE_INDEPENDENT;
  if (HAL_ADCEx_MultiModeConfigChannel(&hadc1, &multimode) != HAL_OK)
  {
    Error_Handler();
  }
  /** Configure Regular Channel 
  */
  sConfig.Channel = ADC_CHANNEL_3;
  sConfig.Rank = ADC_REGULAR_RANK_1;
  sConfig.SamplingTime = ADC_SAMPLETIME_1CYCLE_5;
  sConfig.SingleDiff = ADC_SINGLE_ENDED;
  sConfig.OffsetNumber = ADC_OFFSET_NONE;
  sConfig.Offset = 0;
  if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
  {
    Error_Handler();
  } 
}
 
static void MX_USART1_UART_Init(void)
{
 
  /* USER CODE BEGIN USART1_Init 0 */
 
  /* USER CODE END USART1_Init 0 */
 
  /* USER CODE BEGIN USART1_Init 1 */
 
  /* USER CODE END USART1_Init 1 */
  huart1.Instance = USART1;
  huart1.Init.BaudRate = 115200;//19200;//115200;
  huart1.Init.WordLength = UART_WORDLENGTH_8B;
  huart1.Init.StopBits = UART_STOPBITS_1;
  huart1.Init.Parity = UART_PARITY_NONE;
  huart1.Init.Mode = UART_MODE_TX_RX;
  huart1.Init.HwFlowCtl = UART_HWCONTROL_NONE;
  huart1.Init.OverSampling = UART_OVERSAMPLING_16;
  huart1.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart1.Init.ClockPrescaler = UART_PRESCALER_DIV32;//UART_PRESCALER_DIV32;//UART_PRESCALER_DIV1;
  huart1.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&huart1) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetTxFifoThreshold(&huart1, UART_TXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_SetRxFifoThreshold(&huart1, UART_RXFIFO_THRESHOLD_1_8) != HAL_OK)
  {
    Error_Handler();
  }
  if (HAL_UARTEx_DisableFifoMode(&huart1) != HAL_OK)
  {
    Error_Handler();
  }
  /* USER CODE BEGIN USART1_Init 2 */
 
  /* USER CODE END USART1_Init 2 */
 
}
 
/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
	GPIO_InitTypeDef GPIO_InitStruct = {0};
	
  /* GPIO Ports Clock Enable */
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOB_CLK_ENABLE();
	__HAL_RCC_GPIOE_CLK_ENABLE();
	
	GPIO_InitStruct.Pin = GPIO_PIN_9;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOE, &GPIO_InitStruct);
	HAL_GPIO_WritePin(GPIOE, GPIO_PIN_9, GPIO_PIN_RESET);	
 
}
 
/* USER CODE BEGIN 4 */
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
													//HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_9);
	//if((!strncmp("RD",recbuf+3,2)) || (!strncmp("WD",recbuf+3,2)))
		rec_data=1;
	//else
	//	rec_data=0;
}
 
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
	HAL_UART_Receive_IT(&huart1,recbuf,80);//100
}

I am sending back the received character in the UART_RxISR_8BIT function.

static void UART_RxISR_8BIT(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);
    huart->pRxBuffPtr++;
		HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_9);	
		HAL_UART_Transmit_IT(huart,(uint8_t *)&uhdata,1);
		if(uhdata == '\0')
		{
			//HAL_GPIO_TogglePin(GPIOE, GPIO_PIN_9);	
			huart->RxXferCount = 1;
		}
					
    huart->RxXferCount--;
 
    if (huart->RxXferCount == 0U)
    {
      /* Disable the UART Parity Error Interrupt and RXNE interrupts */
      CLEAR_BIT(huart->Instance->CR1, (USART_CR1_RXNEIE_RXFNEIE | USART_CR1_PEIE));
 
      /* Disable the UART Error Interrupt: (Frame error, noise error, overrun error) */
      CLEAR_BIT(huart->Instance->CR3, USART_CR3_EIE);
 
      /* Rx process is completed, restore huart->RxState to Ready */
      huart->RxState = HAL_UART_STATE_READY;
 
      /* Clear RxISR function pointer */
      huart->RxISR = NULL;
 
#if (USE_HAL_UART_REGISTER_CALLBACKS == 1)
      /*Call registered Rx complete callback*/
      huart->RxCpltCallback(huart);
#else
      /*Call legacy weak Rx complete callback*/
      HAL_UART_RxCpltCallback(huart);
#endif /* USE_HAL_UART_REGISTER_CALLBACKS */
    }
  }
  else
  {
    /* Clear RXNE interrupt flag */
    __HAL_UART_SEND_REQ(huart, UART_RXDATA_FLUSH_REQUEST);
  }
}

.Attached is the Hterm screenshot of received data