/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; Copyright (c) 2021 STMicroelectronics.
  * All rights reserved.</center></h2>
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                        opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "tim.h"
#include "usart.h"
#include "gpio.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 */
#define INIT          0
#define SEND_TRIG     1
#define WAIT_TRIG_END 2
#define WAIT_ECHO_END 3
#define CALC_DIST     4
/* USER CODE END PD */
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */
/* Private variables ---------------------------------------------------------*/
/* USER CODE BEGIN PV */
uint8_t curr_state, next_state;
uint8_t trig_pulse_end, echo_pulse_end;
/* 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 */
  int echo_time;
  float echo_dist;
  /* 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_TIM2_Init();
  MX_TIM3_Init();
  /* USER CODE BEGIN 2 */
  curr_state = INIT;
  next_state = INIT;
  trig_pulse_end = 0;
  echo_pulse_end = 0;
  /* USER CODE END 2 */
 
 
  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
   switch(curr_state) {
   case INIT:
       next_state = SEND_TRIG;
       break;
   case SEND_TRIG:
       next_state = WAIT_TRIG_END;
       break;
   case WAIT_TRIG_END:
       next_state = (trig_pulse_end) ? WAIT_ECHO_END : WAIT_TRIG_END;
       break;
   case WAIT_ECHO_END:
       next_state = (echo_pulse_end) ? CALC_DIST : WAIT_ECHO_END;
       break;
   default: // CALC_DIST
       next_state = INIT;
       break;
   }
      /* USER CODE END WHILE */
      /* USER CODE BEGIN 3 */
   if (curr_state == INIT) {
       trig_pulse_end = 0;
       echo_pulse_end = 0;
       htim2.Instance->CNT = 0;
       htim3.Instance->CNT = 0;
   }
   else if (curr_state == SEND_TRIG) {
       HAL_GPIO_WritePin(GPIOA, GPIO_PIN_11, GPIO_PIN_SET);
       HAL_TIM_Base_Start_IT(&htim2);  // Textbook P.313
   }
   else if (curr_state == CALC_DIST) {
       echo_time = htim3.Instance->CNT;
       echo_dist = (0.00034 * ((float) echo_time)) / 2.0;
       if (echo_dist <= 0.1)
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_SET);
       else
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_5, GPIO_PIN_RESET);
   }
   curr_state = next_state;
  }
  /* USER CODE END 3 */
}
/**
  * @brief System Clock Configuration
  * @retval None
  */
void SystemClock_Config(void)
{
  RCC_OscInitTypeDef RCC_OscInitStruct = {0};
  RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
  /** Initializes the CPU, AHB and APB busses clocks 
  */
  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_DIV2;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL16;
  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_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
  RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
  RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
  RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
  if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
  {
    Error_Handler();
  }
}
/* USER CODE BEGIN 4 */
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
 if (htim->Instance == TIM2) {
        HAL_TIM_Base_Stop_IT(htim);
        HAL_GPIO_WritePin(GPIOA, GPIO_PIN_11, GPIO_PIN_RESET);
        trig_pulse_end = 1;
 }
}
void HAL_GPIO_EXTI_Callback(uint16_t GPIO_Pin)
{
 if (GPIO_Pin == GPIO_PIN_12) { // Interrupt from Echo signal
    if (HAL_GPIO_ReadPin(GPIOA, GPIO_PIN_12) == GPIO_PIN_SET)
     HAL_TIM_Base_Start(&htim3);
    else {
     HAL_TIM_Base_Stop(&htim3);
     echo_pulse_end = 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 */
  /* 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,
     tex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
 
위와같이 최대한 코딩을 하였으나.. FND로 출력값을 나타내주는 코딩을 잘못하겠어요... 어디에 어떤 코딩을 해야할지랑 빠진 것이 있나..모르겠습니다... 도와주세요....