cancel
Showing results for 
Search instead for 
Did you mean: 

USART receive data receiving '0' when nothing is transmitting from tereterm

PB.4
Associate II

Hello team,

please find below my code for receiving the dat from the tera term and after flashing the code could see the rx_data is properly initialized and after pressing the resume option in the debugging environment the first byte of the rx_data is receiving the value of '0' even nothing is sending from the tera term.

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2021 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"
 
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
 
/* USER CODE END Includes */
 
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
 
/* 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 ---------------------------------------------------------*/
UART_HandleTypeDef huart1;
 
/* USER CODE BEGIN PV */
 
/* USER CODE END PV */
 
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART1_UART_Init(void);
/* USER CODE BEGIN PFP */
 
/* USER CODE END PFP */
 
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
static uint8_t rx_data[10] = {"123456789"};
static uint8_t startLedToggle = 0;
static HAL_StatusTypeDef txfrRtrnVal = HAL_ERROR;
static HAL_StatusTypeDef rcvtrnValue = HAL_ERROR;
/* USER CODE END 0 */
 
/**
  * @brief  The application entry point.
  * @retval int
  */
int main(void)
{
  /* USER CODE BEGIN 1 */
 
  /* 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_USART1_UART_Init();
  /* USER CODE BEGIN 2 */
 
  /* USER CODE END 2 */
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  	HAL_GPIO_WritePin(LED_P4A_GPIO_Port, LED_P4A_Pin, 1);
	while (1)
	{
	if(startLedToggle == 0)
	{
		rcvtrnValue = HAL_UART_Receive_IT(&huart1, rx_data, 10);
	}
	if(startLedToggle == 1)
	{
		txfrRtrnVal = HAL_UART_Transmit_IT(&huart1, rx_data, 10);
	}
	if(startLedToggle == 2)
	{
		HAL_GPIO_WritePin(LED_P4A_GPIO_Port, LED_P4A_Pin, 0);
	}
 
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}
 
/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  RCC_PeriphCLKInitTypeDef PeriphClkInit = {0};
 
  /** Initializes the RCC Oscillators according to the specified parameters
  * in the RCC_OscInitTypeDef structure.
  */
  RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
  RCC_OscInitStruct.HSEState = RCC_HSE_ON;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
  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_HSE;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
 
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART1;
  PeriphClkInit.Usart1ClockSelection = RCC_USART1CLKSOURCE_PCLK1;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
  {
    Error_Handler();
  }
}
 
/**
  * @brief USART1 Initialization Function
  * @param None
  * @retval None
  */
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 = 9600;
  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.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  if (HAL_UART_Init(&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_GPIOF_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
 
  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(LED_P4A_GPIO_Port, LED_P4A_Pin, GPIO_PIN_RESET);
 
  /*Configure GPIO pin : LED_P4A_Pin */
  GPIO_InitStruct.Pin = LED_P4A_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(LED_P4A_GPIO_Port, &GPIO_InitStruct);
 
}
 
/* USER CODE BEGIN 4 */
void HAL_UART_TxCpltCallback(UART_HandleTypeDef *huart)
{
	startLedToggle = 2;
}
void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
	startLedToggle = 1;
}
/* 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.
  * @param  file: pointer to the source file name
  * @param  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 */
 

0693W00000HqOTwQAN.png0693W00000HqOZWQA3.png 

Also the received data is not reaching to the tera term, can anyone guide me here?

6 REPLIES 6
TDK
Guru

Maybe make your program simpler. Separate the TX side from the RX side logic. Do a single transmission to verify functionality.

Put the PC-side in loopback mode by connecting RX and TX and verifying functionality.

Might be time to invest in a logic analyzer.

What board is this? Custom board or known good hardware?

Duplicates/Related:

https://community.st.com/s/question/0D53W00001HcAhLSAV/framing-error-overrun-error-occurs-in-uart-while-transmitting-the-character

https://community.st.com/s/question/0D53W00001HabeNSAR/stm32f030f4p6-usart-transmit-is-not-happening-correctly

If you feel a post has answered your question, please click "Accept as Solution".
MM..1
Chief II

This never will work...

while (1)
	{
	if(startLedToggle == 0)
	{
		rcvtrnValue = HAL_UART_Receive_IT(&huart1, rx_data, 10);
	}
	if(startLedToggle == 1)
	{
		txfrRtrnVal = HAL_UART_Transmit_IT(&huart1, rx_data, 10);
	}
	if(startLedToggle == 2)
	{
		HAL_GPIO_WritePin(LED_P4A_GPIO_Port, LED_P4A_Pin, 0);
	}
 
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
  }

if(startLedToggle == 0)

{

rcvtrnValue = HAL_UART_Receive_IT(&huart1, rx_data, 10);

}

say MCU start receive 10 bytes on background and in while 1 and MCU around 50MHZ this command is repeated maybe one milion per second...

Your code need one set and do other job or wait for example

while (1)
  {
	if(startLedToggle == 0)
	{
		rcvtrnValue = HAL_UART_Receive_IT(&huart1, rx_data, 10);
                startLedToggle = 5;   //wait
	}
	if(startLedToggle == 1)
	{
		txfrRtrnVal = HAL_UART_Transmit_IT(&huart1, rx_data, 10);
                startLedToggle = 5;   //wait
	}
	if(startLedToggle == 2)
	{
		HAL_GPIO_WritePin(LED_P4A_GPIO_Port, LED_P4A_Pin, 0);
	}
 
    /* USER CODE END WHILE */
 
    /* USER CODE BEGIN 3 */
  }

PB.4
Associate II

Hello @MM..1​  thanks for your reply. I have modified the code as per your suggestion, but still I could not see the data which is sent from the terminal received by the uC, but the variable 'startLedToggle' becomes 7 and the LED is started glowing, I'm really struck to understand the reason. Initally I though it could be baud rate sync issue, hence I have tested in another PC as well but the same behavior, but while connecting the Tx pin to Rx (loop back) and changed the code as to transmit the data and receive the data, then the receive buffer hold the value send from transmit buffer, so I'm not in a position to conclude wither it is a HW problem or even PC problem, I bough the development board from the below vendor

https://robu.in/product/stm32f030f4p6-core-board-development-board-core-arm-cortex-m0/

Kindly guide me. Thanks in advance!!!

while(1)
{
               if(startLedToggle == 0)
	  	{
	  		rcvtrnValue = HAL_UART_Receive_IT(&huart1, rx_data, 10);
	  		startLedToggle = 5;
	  	}
	  	if(startLedToggle == 1)
	  	{
	  		txfrRtrnVal = HAL_UART_Transmit_IT(&huart1, rx_data, 10);
	  		startLedToggle = 6;
	  	}
	  	if(startLedToggle == 2)
	  	{
	  		HAL_GPIO_WritePin(LED_P4A_GPIO_Port, LED_P4A_Pin, 0);
	  		startLedToggle = 7;
	  	}
}

After transmit you need start new RX then last if need change

	  	if(startLedToggle == 2)
	  	{
	  		HAL_GPIO_WritePin(LED_P4A_GPIO_Port, LED_P4A_Pin, 0);
	  		startLedToggle = 0;
	  	}

and you see data send from terminal only on every 10 bytes or chars sended.

PB.4
Associate II

Hello @MM..1​ , once again reception of 10 bytes are not required, also the data which is seeing in the terminal only after receiving 10 bytes. But the issue is the bytes transmitted to the PC is not the same as the data send from PC to uC.

Maybe good is show what you sent and receive...