STM32-DHT11-main.c

by Marwen Maghrebi
written by Marwen Maghrebi 
  1. /* Includes ------------------------------------------------------------------*/
  2. #include "main.h"
  3.  
  4. /* Private includes ----------------------------------------------------------*/
  5. /* USER CODE BEGIN Includes */
  6. #include<string.h>
  7. #include<stdio.h>
  8.  
  9. /* Private define ------------------------------------------------------------*/
  10. /* USER CODE BEGIN PD */
  11. #define DHT11_Pin GPIO_PIN_0
  12. #define DHT11_GPIO_Port GPIOA
  13. /* USER CODE END PD */
  14.  
  15. /* Private variables ---------------------------------------------------------*/
  16. TIM_HandleTypeDef htim1;
  17.  
  18. UART_HandleTypeDef huart1;
  19.  
  20. /* USER CODE BEGIN PV */
  21. char msg[50] ;
  22. char message1[16];
  23. char message1[16];
  24. uint8_t TOUT =0 , CheckSum , i;
  25. uint8_t T_Byte1 , T_Byte2 , RH_Byte1 , RH_Byte2 ;
  26.  
  27. /* USER CODE END PV */
  28.  
  29.  
  30. /* Private function prototypes -----------------------------------------------*/
  31. void SystemClock_Config(void);
  32. static void MX_GPIO_Init(void);
  33. static void MX_TIM1_Init(void);
  34. static void MX_USART1_UART_Init(void);
  35. /* USER CODE BEGIN PFP */
  36.  
  37. /* USER CODE BEGIN 0 */
  38. void start_signal (void){
  39.      GPIO_InitTypeDef GPIO_InitStruct = {0};
  40.  
  41.  
  42.       GPIO_InitStruct.Pin = DHT11_Pin;
  43.       GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  44.       GPIO_InitStruct.Pull = GPIO_NOPULL;
  45.       GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  46.       HAL_GPIO_Init(DHT11_GPIO_Port, &GPIO_InitStruct);
  47.  
  48.       HAL_GPIO_WritePin(DHT11_GPIO_Port, DHT11_Pin, GPIO_PIN_RESET);
  49.       HAL_Delay(18);
  50.       HAL_GPIO_WritePin(DHT11_GPIO_Port, DHT11_Pin, GPIO_PIN_SET);
  51.       delay_us(30);
  52.  
  53.       GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
  54.       HAL_GPIO_Init(DHT11_GPIO_Port, &GPIO_InitStruct);
  55.  
  56. }
  57.  
  58. void delay_us ( uint16_t us)
  59. {
  60.     __HAL_TIM_SET_COUNTER(&htim1,0);
  61.     while(__HAL_TIM_GET_COUNTER(&htim1) < us);
  62. }
  63.  
  64. uint8_t check_response(void){
  65.     TOUT=0;
  66.     __HAL_TIM_SET_COUNTER(&htim1,0);
  67.     while(!HAL_GPIO_ReadPin(DHT11_GPIO_Port, DHT11_Pin) && (__HAL_TIM_GET_COUNTER(&htim1) < 100)) {};
  68.     if(__HAL_TIM_GET_COUNTER(&htim1)>= 100){
  69.         return 0; //timeout
  70.     }
  71.     while(HAL_GPIO_ReadPin(DHT11_GPIO_Port, DHT11_Pin) && (__HAL_TIM_GET_COUNTER(&htim1) < 100)) {};
  72.         if(__HAL_TIM_GET_COUNTER(&htim1)>= 100){
  73.             return 0; //timeout
  74.         }
  75.     return 1;
  76. }
  77.  
  78. uint8_t read_byte(void){
  79.     uint8_t num =0 ;
  80.     for(i=0 ;i<8; i++){
  81.         while(!HAL_GPIO_ReadPin(DHT11_GPIO_Port, DHT11_Pin))  {};
  82.         __HAL_TIM_SET_COUNTER(&htim1,0);
  83.         while(HAL_GPIO_ReadPin(DHT11_GPIO_Port, DHT11_Pin))  {};
  84.         if(__HAL_TIM_GET_COUNTER(&htim1) > 40)
  85.         {
  86.             num |= (1 << (7 - i));
  87.         }
  88.  
  89.     }
  90.     return num;
  91. }
  92.  
  93. void process_sensor_data(void){
  94.     RH_Byte1 = read_byte();
  95.     RH_Byte2 = read_byte();
  96.     T_Byte1 = read_byte();
  97.     T_Byte2 = read_byte();
  98.     CheckSum = read_byte();
  99.  
  100.     uint8_t humidity_integer =  RH_Byte1 ;
  101.     uint8_t humidity_decimal =  RH_Byte2 / 10 ;
  102.  
  103.     uint8_t temperature_integer =  T_Byte1 ;
  104.     uint8_t temperature_decimal =  T_Byte2 / 10 ;
  105.  
  106.     if(CheckSum ==((RH_Byte1+RH_Byte2 +T_Byte1+T_Byte2)& 0xff)){
  107.         snprintf(msg,sizeof(msg),"RH = %d.%d %%\r\n",humidity_integer,humidity_decimal);
  108.         send_uart_message(msg);
  109.         snprintf(msg,sizeof(msg),"temp = %d.%d C\r\n",temperature_integer,temperature_decimal);
  110.         send_uart_message(msg);
  111.  
  112.     }else
  113.     {
  114.         send_uart_message("Checksum Errors ! Trying Again ...\r\n");
  115.     }
  116. }
  117.  
  118. void send_uart_message(char *messsage){
  119.     HAL_UART_Transmit(&huart1, (uint8_t*)messsage, strlen(messsage), HAL_MAX_DELAY);
  120. }
  121. /* USER CODE END 0 */
  122.  
  123. int main(void)
  124. {
  125.  
  126.   /* Reset of all peripherals, Initializes the Flash interface and the Systick. */
  127.   HAL_Init();
  128.   /* Configure the system clock */
  129.   SystemClock_Config();
  130.   /* Initialize all configured peripherals */
  131.   MX_GPIO_Init();
  132.   MX_TIM1_Init();
  133.   MX_USART1_UART_Init();
  134.   /* USER CODE BEGIN 2 */
  135.  HAL_TIM_Base_Start(&htim1);
  136.  send_uart_message("Initilization complet \n\r");
  137.   /* USER CODE END 2 */
  138.  
  139.   /* Infinite loop */
  140.   /* USER CODE BEGIN WHILE */
  141.   while (1)
  142.   {
  143.     /* USER CODE END WHILE */
  144.  
  145.     /* USER CODE BEGIN 3 */
  146.       HAL_Delay(1000); // 1 second delay before starting
  147.       start_signal();
  148.       uint8_t check = check_response();
  149.       if (!check){
  150.           send_uart_message("No responce from the sensor \r\n");
  151.       } else {
  152.           process_sensor_data();
  153.       }
  154.  
  155.   }
  156.   /* USER CODE END 3 */
  157. }

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