승코딩당당당

[STM32] UART 통신 확인 실습 (PuTTY) 본문

개발/임베디드

[STM32] UART 통신 확인 실습 (PuTTY)

승코딩당당당 2026. 2. 6. 17:43

 

이 코드는 STM32L0 NUCLEO 보드에서

  1. 보드 부팅 시 UART로 “Hello World”를 PuTTY에 출력하고,
  2. 진동 센서(또는 외부 인터럽트 입력)의 발생 횟수에 따라 LED를 점멸시키며,
  3. USER 버튼을 누르면 진동 카운트를 리셋하는 인터럽트 기반 동작

을 구현한 예제다.

단순히 GPIO를 토글하는 수준을 넘어서,

  • UART 통신 초기화
  • BSP(Basic Support Package)를 이용한 LED / 버튼 추상화
  • EXTI 인터럽트 콜백 활용

까지 한 번에 연습하는 코드라고 보면 된다.

 

 

먼저 CubeMX에서 다음과 같이 PA2와 PA3을 각각 USART2_TX, RX로 설정해준다.

 

 

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2026 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 "stm32l0xx_nucleo.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 ---------------------------------------------------------*/
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 */

// interrupt mode (USER_BUTTON) -> override 'weak void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)'
volatile uint32_t nVibCnt = 0;
volatile uint8_t bVib = 0;

void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin) {
	switch(GPIO_Pin){
		case USER_BUTTON_PIN:
			bVib = 0;
			nVibCnt = 0;
			BSP_LED_Off(LED1);
			//BSP_LED_Off(USER_LED1);
			break;
		case USER_VIB_Pin:
			if(nVibCnt>300){
				bVib = 1;
				return;
			}
			else{
				nVibCnt++;
			}
			break;
	}
	
}

/* 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 */
	// UART
  char msg[] = "Hello World\r\n";

  HAL_UART_Transmit(&huart2, (uint8_t*)msg, strlen(msg), 1000);

  LEDx_GPIO_CLK_ENABLE(LEDn);

  BSP_LED_Init(LED1); // PA8
  BSP_LED_Init(LED2); // PA5
  // BSP_LED_Init(LED3); // PB5

  BSP_PB_Init(BUTTON_USER, BUTTON_MODE_EXTI);

	// -----------------
	// before using CubeMX
	
	// GPIO_InitTypeDef initVal;
	
	// initVal.Pin = GPIO_PIN_5;
	// initVal.Mode = GPIO_MODE_OUTPUT_PP;
	// initVal.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
	// initVal.Pull = GPIO_NOPULL;
	
	// HAL_GPIO_Init(GPIOA, &initVal);
	// HAL_GPIO_Init(GPIOB, &initVal);
	
	// HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_SET);
	// HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, GPIO_PIN_RESET);
	// ------------------
	
	// after using CubeMX
	// this in GPIO_init()
	
	// after using BSP
	LEDx_GPIO_CLK_ENABLE(LEDn);
	
	BSP_LED_Init(LED1); // PA8
	BSP_LED_Init(LED2); // PA5
//	BSP_LED_Init(LED3); // PB5
	
	// BSP_PB_Init(BUTTON_USER, BUTTON_MODE_GPIO);  // USER BUTTON (polling mode)
	BSP_PB_Init(BUTTON_USER, BUTTON_MODE_EXTI);  // USER BUTTON (interrupt mode)
	
	// BSP_LED_Off(LED1);
	// BSP_LED_On(LED2);
	// BSP_LED_On(LED3);
	
  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
		/* // do not use delay in while !!!!!!!!!!! (we are testing)
		   //		-> Then Use !!!!! Timer !!!!! */
		// HAL_Delay(100);
		
		// ------------------
		// before using CubeMX
		
		// HAL_GPIO_TogglePin(GPIOA, GPIO_PIN_5);
		// HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_5);
		
		//---------------------
		
		// --------------------
		// after using CubeMX
		
		// HAL_GPIO_TogglePin(GPIOA, USER_LED_PA5_Pin);
		// HAL_GPIO_TogglePin(GPIOB, USER_LED_PB5_Pin);
		// HAL_GPIO_TogglePin(GPIOA, USER_LED_PA8_Pin);
		
		// ---------------------
		
		// after using BSP
		
		// BSP_LED_Toggle(LED1);
		// BSP_LED_Toggle(LED2);
		// BSP_LED_Toggle(LED3);
		
		// // polling
		// if (!BSP_PB_GetState(BUTTON_USER)) {  // pull-up (when BUTTON clicked -> state 0)
		// 	BSP_LED_On(LED1);
		// 	BSP_LED_On(LED2);
		// 	BSP_LED_On(LED3);
		// }
		
		// BSP_LED_Off(LED1);
		// BSP_LED_Off(LED2);
		// BSP_LED_Off(LED3);
		
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
		if(bVib){
			BSP_LED_Toggle(LED1);
		}
  }
  /* 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};

  /** Configure the main internal regulator output voltage
  */
  __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_MSI;
  RCC_OscInitStruct.MSIState = RCC_MSI_ON;
  RCC_OscInitStruct.MSICalibrationValue = 0;
  RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_5;
  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_CLOCKTYPE_PCLK2;
  RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
  {
    Error_Handler();
  }
  PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_USART2;
  PeriphClkInit.Usart2ClockSelection = RCC_USART2CLKSOURCE_PCLK1;
  if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != 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 = 9600;
  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;
  huart2.Init.OneBitSampling = UART_ONE_BIT_SAMPLE_DISABLE;
  huart2.AdvancedInit.AdvFeatureInit = UART_ADVFEATURE_NO_INIT;
  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_GPIOC_CLK_ENABLE();
  __HAL_RCC_GPIOH_CLK_ENABLE();
  __HAL_RCC_GPIOA_CLK_ENABLE();
  __HAL_RCC_GPIOB_CLK_ENABLE();

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(GPIOA, GPIO_PIN_8, GPIO_PIN_RESET);

  /*Configure GPIO pin : PC13 */
  GPIO_InitStruct.Pin = GPIO_PIN_13;
  GPIO_InitStruct.Mode = GPIO_MODE_IT_RISING;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);

  /*Configure GPIO pin : PA7 */
  GPIO_InitStruct.Pin = GPIO_PIN_7;
  GPIO_InitStruct.Mode = GPIO_MODE_IT_RISING;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  /*Configure GPIO pin : PA8 */
  GPIO_InitStruct.Pin = GPIO_PIN_8;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);

  /*Configure GPIO pin : USER_VIB_Pin */
  GPIO_InitStruct.Pin = USER_VIB_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_IT_RISING;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(USER_VIB_GPIO_Port, &GPIO_InitStruct);

  /* EXTI interrupt init*/
  HAL_NVIC_SetPriority(EXTI4_15_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(EXTI4_15_IRQn);

  /* 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 */

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