PuTTy not receiving data from UART

[pb33]

Hello, 

I am using the STMH753ZI chip on the nucleo 144 board. I cannot figure out why my UART code will not show what I am typing in my putty terminal. Attached is my main.c. Thanks. 

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2025 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 "uart.h"

/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "initializer.h"
#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 ---------------------------------------------------------*/

COM_InitTypeDef BspCOMInit;
__IO uint32_t BspButtonState = BUTTON_RELEASED;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

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

/* USER CODE END PFP */

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

/* 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();
  MX_USART3_UART_Init();
  /* USER CODE BEGIN 2 */

  HAL_UART_Receive_IT(&huart3, rx_data, 6);
  /* USER CODE END 2 */

  /* Initialize leds */
  BSP_LED_Init(LED_GREEN);
  BSP_LED_Init(LED_BLUE);
  BSP_LED_Init(LED_RED);

  /* Initialize USER push-button, will be used to trigger an interrupt each time it's pressed.*/
  BSP_PB_Init(BUTTON_USER, BUTTON_MODE_EXTI);

  /* Initialize COM1 port (115200, 8 bits (7-bit data + 1 stop bit), no parity */
  BspCOMInit.BaudRate   = 115200;
  BspCOMInit.WordLength = COM_WORDLENGTH_8B;
  BspCOMInit.StopBits   = COM_STOPBITS_1;
  BspCOMInit.Parity     = COM_PARITY_NONE;
  BspCOMInit.HwFlowCtl  = COM_HWCONTROL_NONE;
  if (BSP_COM_Init(COM1, &BspCOMInit) != BSP_ERROR_NONE)
  {
    Error_Handler();
  }

  /* USER CODE BEGIN BSP */

  /* -- Sample board code to send message over COM1 port ---- */
  printf("Welcome to STM32 world !\n\r");

  /* -- Sample board code to switch on leds ---- */
//  BSP_LED_On(LED_GREEN);
//  BSP_LED_On(LED_BLUE);
//  BSP_LED_On(LED_RED);

  /* USER CODE END BSP */

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

    /* -- Sample board code for User push-button in interrupt mode ---- */
//    if (BspButtonState == BUTTON_PRESSED)
//    {
//      /* Update button state */
//      BspButtonState = BUTTON_RELEASED;
//      /* -- Sample board code to toggle leds ---- */
//      BSP_LED_Toggle(LED_GREEN);
//      BSP_LED_Toggle(LED_BLUE);
//      BSP_LED_Toggle(LED_RED);
//
//      /* ..... Perform your action ..... */
//    }




    /* USER CODE END WHILE */
//	  HAL_UART_Transmit(&huart3, tx_buffer, strlen((char*)tx_buffer), 10);
//	  HAL_Delay(1000);




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

/**
  * @brief BSP Push Button callback
  * @PAram Button Specifies the pressed button
  * @retval None
  */
void BSP_PB_Callback(Button_TypeDef Button)
{
  if (Button == BUTTON_USER)
  {
    BspButtonState = BUTTON_PRESSED;
  }
}

/**
  * @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 */

[Andrew Neil]

---

@pb33 wrote:

 when I try to also type strings in manually, nothing shows up. 

---

Where and how are you expecting them to "show up" ?

You still haven't answered the questions:

• what have you tried so far to debug the problem?
• Have you put an oscilloscope probe onto the STM32 UART's RX pin to see if anything is actually reaching there?
• You're using UART3 - how is that routed to your PuTTY terminal ?
• Before trying the added complexities of interrupts, have you got it working using the basic, blocking HAL_UART_Receive() ?
• I can't see a callback for your UART receive?