[MCU] 【AT-START-F403A测评】+DHT22温湿度检测及显示

jinglixixi 2020-10-15 21:03 楼主

除了显示器件的驱动，对各种数字传感器的驱动也是一件十分有益的事情。

这里就介绍一款单总线数字式温湿度传感器的驱动方法，该器件为DHT22，它较之于DHT11的精度更高，可达小数点后1位。

使用该器件时，其数据引脚与PB11相连接，故有如下的输出高低电平及读取引脚状态的定义引脚：

#define DHT22_D0_H GPIOB->BSRE = GPIO_Pins_15

#define DHT22_D0_L GPIOB->BRE = GPIO_Pins_15

#define DHT22_D0_R GPIO_ReadInputDataBit(GPIOB, GPIO_Pins_15)

对DHT22初始化的函数为：

uint8_t DHT22_Init(void)
{
      GPIO_InitType GPIO_InitStructure;
      RCC_APB2PeriphClockCmd(RCC_APB2PERIPH_GPIOB, ENABLE);
      GPIO_StructInit(&GPIO_InitStructure);
      GPIO_InitStructure.GPIO_Pins = GPIO_Pins_15;
      GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT_PP;
      GPIO_InitStructure.GPIO_MaxSpeed = GPIO_MaxSpeed_10MHz;
      GPIO_Init(GPIOB, &GPIO_InitStructure);
      DHT22_Rst();
      return DHT22_Check();
}

读取DHT22数据的函数为：

uint8_t DHT22_Read_Data(uint8_t *temp,uint8_t *humi)   
{       
         uint8_t buf[5];
         uint8_t i;
         DHT22_Rst();
         if(DHT22_Check()==0)
         {
                   for(i=0;i<5;i++)
                   {
                            buf[i]=DHT22_Read_Byte();
                   }
                   if((buf[0]+buf[1]+buf[2]+buf[3])==buf[4])
                   {
                            *humi=(buf[0]*256+buf[1])/10;
                            *temp=(buf[2]*256+buf[3])/10;
                   }
         }else return 1;
         return 0; 
}

实现温湿度检测功能程序如下：

if(i==4)
{
           showhanzi16h(80,100,5,1);
           showhanzi16h(80,84,6,1);
           showhanzi16h(180,280,13,0);
           showhanzi16h(180,264,14,0);        
           while(GPIO_ReadInputDataBit(GPIOA, GPIO_Pins_0)==0);
           LCD_Clear(WHITE);         
           show_imageh(10,300,0);  //200*200 * 1     
           BACK_COLOR=WHITE;
           POINT_COLOR=RED;
           LCD_ShowStringH(60,90,"DHT22 TEST");
           senflag=DHT22_Init();    
           if(senflag) LCD_ShowStringH(80,90,"NO");
           else   LCD_ShowStringH(80,90,"OK");
           while(GPIO_ReadInputDataBit(GPIOA, GPIO_Pins_0)==0)
           {
                  if(!senflag)
                  {
                     DHT22_Read_Data(&temperature,&humidity);
                     LCD_ShowCharh(100,90,'T',1);
                     LCD_ShowCharh(100,80,'e',1);
                     LCD_ShowCharh(100,70,'m',1);
                     LCD_ShowCharh(100,60,'p',1);
                     LCD_ShowCharh(100,50,':',1);
                     LCD_ShowCharh(100,40,temperature/10+'0',0);
                     LCD_ShowCharh(100,30,temperature%10+'0',0);
                     LCD_ShowCharh(120,90,'H',1);
                     LCD_ShowCharh(120,80,'u',1);
                     LCD_ShowCharh(120,70,'m',1);
                     LCD_ShowCharh(120,60,'i',1);
                     LCD_ShowCharh(120,50,':',1);
                     LCD_ShowCharh(120,40,humidity/10+'0',0);
                     LCD_ShowCharh(120,30,humidity%10+'0',0);
                  }
                  Delay_ms(200u);
          }
          LCD_Clear(WHITE);
          AT32_jm();
          showhanzi16h(80,100,5,1);
          showhanzi16h(80,84,6,1);
          showhanzi16h(180,280,13,0);
          showhanzi16h(180,264,14,0);
}

该程序的运行效果如图1和图2所示，其中图1为选取环境检测功能，图2位温湿度显示界面。