Skip to main content
Graduate II
December 26, 2024
Solved

Only the first byte of transmitted message is received by UART Rx

  • December 26, 2024
  • 1 reply
  • 1110 views

Hi,

 

I want to send a simple message through UART and check if message is properly received at Rx end. I want to do loopback test. I connect PD5 to PD6, namely short circuit. Then I run the below code. When I debug the code, I can see only the first byte is received. I tried many ways to fix it but cant find out the root cause, eventually cant resolve the issue.

I am looking forward to hearing some help. Thank you.

demir_0-1735205342800.png

 

 

/* USER CODE BEGIN Header */
/**
 ******************************************************************************
 * @file : main.c
 * @brief : Main program body
 ******************************************************************************
 * @attention
 *
 * Copyright (c) 2024 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 */
#include "string.h"

/* 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 huart2;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART2_UART_Init(void);
/* USER CODE BEGIN PFP */

/* USER CODE END PFP */

/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */

uint8_t tx_data[6] = "Hello";
uint8_t rx_data[6];

/* 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_USART2_UART_Init();
 /* USER CODE BEGIN 2 */

 /* USER CODE END 2 */

 /* Infinite loop */
 /* USER CODE BEGIN WHILE */
 while (1)
 {
 /* USER CODE END WHILE */

 /* USER CODE BEGIN 3 */

	 __HAL_UART_FLUSH_DRREGISTER(&huart2);


	 HAL_UART_Transmit(&huart2, tx_data, strlen((char*)tx_data), 5000);
	 HAL_Delay(1000);


	 if (HAL_UART_Receive(&huart2, rx_data, sizeof(rx_data), 5000) != HAL_OK)
	 {
		 HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_13); // Error indicator orange led
	 }


	 if (__HAL_UART_GET_FLAG(&huart2, UART_FLAG_ORE)) {
	 __HAL_UART_CLEAR_OREFLAG(&huart2);
	 HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_15); // Error indicator blue led
	 }

	 if (strcmp((char *)tx_data, (char *)rx_data) == 0) {
	 HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_12); // Indicate success with LED toggle green
	 }
	 else
	 {

	 HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_14); // Toggle LED on pin PD14
	 HAL_Delay(500); // Delay for 500 milliseconds
	 }

//	 if(HAL_UART_Transmit(&huart2, (uint8_t*)message, strlen(message), HAL_MAX_DELAY) == HAL_OK)
//	 {
//		 HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_12); // Toggle LED on pin PD12
//		 HAL_Delay(500); // Delay for 500 milliseconds
//	 }
//
//	 else
//
//	 {
//		 HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_14); // Toggle LED on pin PD14
//		 HAL_Delay(500); // Delay for 500 milliseconds
//	 }
 }
 /* USER CODE END 3 */
}

/**
 * @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_RCC_PWR_CLK_ENABLE();
 __HAL_PWR_VOLTAGESCALING_CONFIG(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.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
 RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
 RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
 RCC_OscInitStruct.PLL.PLLM = 8;
 RCC_OscInitStruct.PLL.PLLN = 84;
 RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
 RCC_OscInitStruct.PLL.PLLQ = 7;
 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_CLOCKTYPE_PCLK2;
 RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
 RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
 RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
 RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;

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

/**
 * @brief USART2 Initialization Function
 * @PAram None
 * @retval None
 */
static void MX_USART2_UART_Init(void)
{

 /* USER CODE BEGIN USART2_Init 0 */

 /* USER CODE END USART2_Init 0 */

 /* USER CODE BEGIN USART2_Init 1 */

 /* USER CODE END USART2_Init 1 */
 huart2.Instance = USART2;
 huart2.Init.BaudRate = 115200;
 huart2.Init.WordLength = UART_WORDLENGTH_8B;
 huart2.Init.StopBits = UART_STOPBITS_1;
 huart2.Init.Parity = UART_PARITY_NONE;
 huart2.Init.Mode = UART_MODE_TX_RX;
 huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
 huart2.Init.OverSampling = UART_OVERSAMPLING_16;
 if (HAL_UART_Init(&huart2) != HAL_OK)
 {
 Error_Handler();
 }
 /* USER CODE BEGIN USART2_Init 2 */

 /* USER CODE END USART2_Init 2 */

}

/**
 * @brief GPIO Initialization Function
 * @PAram None
 * @retval None
 */
static void MX_GPIO_Init(void)
{
 GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */

 /* GPIO Ports Clock Enable */
 __HAL_RCC_GPIOD_CLK_ENABLE();

 /*Configure GPIO pin Output Level */
 HAL_GPIO_WritePin(GPIOD, GPIO_PIN_12|GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15, GPIO_PIN_RESET);

 /*Configure GPIO pins : PD12 PD13 PD14 PD15 */
 GPIO_InitStruct.Pin = GPIO_PIN_12|GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15;
 GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
 GPIO_InitStruct.Pull = GPIO_NOPULL;
 GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);

/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

/* 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.
 * @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 */

 

    This topic has been closed for replies.
    Best answer by demir

    Thank you.

     

    It has been resolved by connect the FT232RL to PC via USB. 

    1 reply

    Super User
    December 26, 2024

    HAL_UART_Transmit is a blocking function, it returns only after the entire message was sent.

    Then, HAL_Delay(1000); waits for another second.

    Then, after all, you start receiving chars with HAL_UART_Receive.

    Where do you expect the message to sit and wait meanwhile? 

    Your approach is inherently broken.

    Look for USART examples that come with HAL STM32CubeF4/Projects at master · STMicroelectronics/STM32CubeF4,

    or Getting started with UART - stm32mcu

    Try communicating with a second board/host PC, or using interrupt / DMA.

    hth

    KnarfB   

     

    demirAuthor
    Graduate II
    December 26, 2024

    Allright, I tried to send data to my PC using FT232RL. Please see my connection at below image.

    demir_0-1735231722943.pngdemir_1-1735231741879.png

     

     

    I have also edited the code please see below.

    I have opened port COM4 through HERCULES (a program to monitor serial port). 

    I still CAN NOT see the message sent to PC on Hercules even I see that green LED blinks which is an indication that message is transmitted.

    However, even I keep sending bytes to PC via hercules, I can not receive it as I see the RED led blinks.

     

    demir_2-1735231757559.png

     

    My port settings are as below.

     

    demir_3-1735231813156.png

     

    I am veryyyyy confused and would be glad if you could support.

    Thanks.

     

    /* USER CODE BEGIN Header */
    /**
     ******************************************************************************
     * @file : main.c
     * @brief : Main program body
     ******************************************************************************
     * @attention
     *
     * Copyright (c) 2024 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 */
    #include "string.h"
    
    /* 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 huart2;
    
    /* USER CODE BEGIN PV */
    
    /* USER CODE END PV */
    
    /* Private function prototypes -----------------------------------------------*/
    void SystemClock_Config(void);
    static void MX_GPIO_Init(void);
    static void MX_USART2_UART_Init(void);
    /* USER CODE BEGIN PFP */
    
    /* USER CODE END PFP */
    
    /* Private user code ---------------------------------------------------------*/
    /* USER CODE BEGIN 0 */
    
    uint8_t tx_data[6] = "Hello";
    uint8_t rx_data[100];
    
    /* 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_USART2_UART_Init();
     /* USER CODE BEGIN 2 */
    
     /* USER CODE END 2 */
    
     /* Infinite loop */
     /* USER CODE BEGIN WHILE */
     while (1)
     {
     /* USER CODE END WHILE */
    
     /* USER CODE BEGIN 3 */
    
    	 if (HAL_UART_Transmit(&huart2, tx_data, strlen((char*)tx_data), 5000) == HAL_OK)
    	 {
    		 HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_12); // green
    	 }
    
    	 if (HAL_UART_Receive(&huart2, rx_data, sizeof(rx_data), 5000) == HAL_OK)
    	 {
    		 HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_13); // orange
    
    	 }
    	 else
    	 {
    		 HAL_Delay(1000);
    		 HAL_GPIO_TogglePin(GPIOD, GPIO_PIN_14); // red
    	 }
    
     }
     /* USER CODE END 3 */
    }
    
    /**
     * @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_RCC_PWR_CLK_ENABLE();
     __HAL_PWR_VOLTAGESCALING_CONFIG(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.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
     RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
     RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI;
     RCC_OscInitStruct.PLL.PLLM = 8;
     RCC_OscInitStruct.PLL.PLLN = 84;
     RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
     RCC_OscInitStruct.PLL.PLLQ = 7;
     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_CLOCKTYPE_PCLK2;
     RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
     RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
     RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV4;
     RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV2;
    
     if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
     {
     Error_Handler();
     }
    }
    
    /**
     * @brief USART2 Initialization Function
     * @PAram None
     * @retval None
     */
    static void MX_USART2_UART_Init(void)
    {
    
     /* USER CODE BEGIN USART2_Init 0 */
    
     /* USER CODE END USART2_Init 0 */
    
     /* USER CODE BEGIN USART2_Init 1 */
    
     /* USER CODE END USART2_Init 1 */
     huart2.Instance = USART2;
     huart2.Init.BaudRate = 115200;
     huart2.Init.WordLength = UART_WORDLENGTH_8B;
     huart2.Init.StopBits = UART_STOPBITS_1;
     huart2.Init.Parity = UART_PARITY_NONE;
     huart2.Init.Mode = UART_MODE_TX_RX;
     huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
     huart2.Init.OverSampling = UART_OVERSAMPLING_16;
     if (HAL_UART_Init(&huart2) != HAL_OK)
     {
     Error_Handler();
     }
     /* USER CODE BEGIN USART2_Init 2 */
    
     /* USER CODE END USART2_Init 2 */
    
    }
    
    /**
     * @brief GPIO Initialization Function
     * @PAram None
     * @retval None
     */
    static void MX_GPIO_Init(void)
    {
     GPIO_InitTypeDef GPIO_InitStruct = {0};
    /* USER CODE BEGIN MX_GPIO_Init_1 */
    /* USER CODE END MX_GPIO_Init_1 */
    
     /* GPIO Ports Clock Enable */
     __HAL_RCC_GPIOD_CLK_ENABLE();
    
     /*Configure GPIO pin Output Level */
     HAL_GPIO_WritePin(GPIOD, GPIO_PIN_12|GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15, GPIO_PIN_RESET);
    
     /*Configure GPIO pins : PD12 PD13 PD14 PD15 */
     GPIO_InitStruct.Pin = GPIO_PIN_12|GPIO_PIN_13|GPIO_PIN_14|GPIO_PIN_15;
     GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
     GPIO_InitStruct.Pull = GPIO_NOPULL;
     GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
     HAL_GPIO_Init(GPIOD, &GPIO_InitStruct);
    
    /* USER CODE BEGIN MX_GPIO_Init_2 */
    /* USER CODE END MX_GPIO_Init_2 */
    }
    
    /* 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.
     * @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 */

     

    Graduate II
    December 27, 2024

    Yeah, out of focus pictures aren't super helpful. Perhaps you can enumerate actual connectivity?

    PD5/PD6

    PD5 (USART2.TX AF7) would presumably need to go to the FTDI RX. Perhaps get a scope or logic probe on the signal.

    Do you get successful reception of data on the PC? Start with that as Step#1

    Blocking and dwelling for 5 seconds to get input on the STM32 probably not ideal. Perhaps use the IT versions so you can get concurrent reception.