DHT11溫溼度傳感器程序設計

本程序對應的開發板爲藍橋杯嵌入式開發板stm32f103rbt6，爲中型mcu。DHT11是單線接口數字溫溼度傳感器，溫度測量範圍是0~50℃，溼度測量範圍是20%~90%RH，溫度測量精度是±2℃，溼度測量精度是±5%RH。

DHT11包含一個電阻式感溼元件和一個NTC（負溫度係數）測溫元件，通過雙向單線輸出溫溼度數據，一次數據輸出爲40位（高位在前，大約需要4ms），數據格式爲：

8位溼度整數+8位溼度小數+8位溫度整數+8位溫度小數+8位校驗和。其中校驗和是前4個8位數據之和的後8位

 

 

讀取步驟

連接：

P4.7（PA7）-P3.7（HDQ）

dht11.c

#include "stm32f10x.h"

#define delay_us(X)  delay(X*72/5)

void delay(unsigned int n)
{
  while (n--);
}

void dht11_init (void )
{
  GPIO_InitTypeDef GPIO_InitStructure;
  /* Enable  clock */
  RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA  , ENABLE);
  
  /* Configure Ports */
  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);

  GPIO_SetBits(GPIOA, GPIO_Pin_7);

}

void mode_input(void )
{
  GPIO_InitTypeDef GPIO_InitStructure;

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
}
void mode_output(void )
{
  GPIO_InitTypeDef GPIO_InitStructure;

  GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;
  GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_PP;
  GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;
  GPIO_Init(GPIOA, &GPIO_InitStructure);
}

unsigned int dht11_read(void)
{
  int i;
  long long val;
  int timeout;

  GPIO_ResetBits(GPIOA, GPIO_Pin_7);
  delay_us(18000);  //pulldown  for 18ms
  GPIO_SetBits(GPIOA, GPIO_Pin_7);
  delay_us( 20 );	//pullup for 30us

  mode_input();

  //等待DHT11拉高，80us
  timeout = 5000;
  while( (! GPIO_ReadInputDataBit  (GPIOA, GPIO_Pin_7)) && (timeout > 0) ) timeout--;	 //wait HIGH

  //等待DHT11拉低，80us
  timeout = 5000;
  while( GPIO_ReadInputDataBit (GPIOA, GPIO_Pin_7) && (timeout > 0) ) timeout-- ;	 //wait LOW

#define CHECK_TIME 28

  for(i=0;i<40;i++)
  {
	timeout = 5000;
	while( (! GPIO_ReadInputDataBit  (GPIOA, GPIO_Pin_7)) && (timeout > 0) ) timeout--;	 //wait HIGH

	delay_us(CHECK_TIME);
	if ( GPIO_ReadInputDataBit (GPIOA, GPIO_Pin_7) )
	{
	  val=(val<<1)+1;
	} else {
	  val<<=1;
	}

	timeout = 5000;
	while( GPIO_ReadInputDataBit (GPIOA, GPIO_Pin_7) && (timeout > 0) ) timeout-- ;	 //wait LOW
  }

  mode_output();
  GPIO_SetBits(GPIOA, GPIO_Pin_7);

  if (((val>>32)+(val>>24)+(val>>16)+(val>>8) -val ) & 0xff  ) return 0;
    else return val>>8; 

}

dht11.h

#ifndef __DHT11_H
#define __DHT11_H

void dht11_init (void );
void delay(unsigned int n);

unsigned int dht11_read(void);

#endif

主程序

#include "stm32f10x.h"
#include "lcd.h"
#include "dht11.h"

u32 TimingDelay = 0;

void Delay_Ms(u32 nTime);
unsigned int Dht_Val;
unsigned char string[20],Sec1,Sec;
unsigned long Tick_Ms;

void  Dht11_Proc(void);


int main(void)
{
  
    STM3210B_LCD_Init();
	LCD_Clear(Blue);
	LCD_SetBackColor(Blue);
	LCD_SetTextColor(White);
	
	SysTick_Config(SystemCoreClock/1000);
	dht11_init();

	
	LCD_DisplayStringLine(Line0,"                    ");	
	LCD_DisplayStringLine(Line1,"                    ");	
	LCD_DisplayStringLine(Line2,"                    ");
	LCD_DisplayStringLine(Line3,"                    ");
	LCD_DisplayStringLine(Line4,"                    ");
	LCD_DisplayStringLine(Line5,"                    ");
	LCD_DisplayStringLine(Line6,"                    ");
	LCD_DisplayStringLine(Line7,"                    ");	
	LCD_DisplayStringLine(Line8,"                    ");
	LCD_DisplayStringLine(Line9,"                    ");	
	

  while (1)
  {
	 Dht11_Proc();
  }
}

void  Dht11_Proc(void)
{
	if(Sec1!=Sec)
	{
	Sec1=Sec;
	Dht_Val=dht11_read();
	sprintf((char*)string,"Humidity: %2d%",Dht_Val>>24);
	LCD_DisplayStringLine(Line1,string);
	sprintf((char*)string,"Temperature: %2dC",(Dht_Val>>8)&0xff);
	LCD_DisplayStringLine(Line4,string);

	}

	


}


void Delay_Ms(u32 nTime)
{
	TimingDelay = nTime;
	while(TimingDelay != 0);	
}


void SysTick_Handler(void)
{
		TimingDelay--;
		Tick_Ms++;
		if(Tick_Ms%1000==0)Sec++;
}