树莓派3b驱动dht11温湿度传感器

最新推荐文章于 2025-03-25 15:58:14 发布

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最新推荐文章于 2025-03-25 15:58:14 发布

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分类专栏： Object C 文章标签：传感器 c

本文链接：https://blog.youkuaiyun.com/m0_37954775/article/details/86150171

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本文介绍了如何在树莓派3B上驱动DHT11温湿度传感器。首先新建并打开C文件，然后编写驱动程序，接着安装wiringPi开发库并编译C文件，最后运行程序成功获取并打印了湿度和温度值。

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树莓派3b驱动dht11温湿度传感器

1.新建并打开C文件

touch dht11.c

sudo vim dht11.c

2.编写驱动程序

 #include<wiringPi.h>
#include<stdio.h>
#include<stdlib.h>
#include<stdint.h>
#define MAX_TIME 85
#define DHT11PIN 7
#define ATTEMPTS 5                 //retry 5 times when no response
int dht11_val[5]={0,0,0,0,0};

int dht11_read_val(){
    uint8_t lststate=HIGH;         //last state
    uint8_t counter=0;
    uint8_t j=0,i;
    for(i=0;i<5;i++)
        dht11_val[i]=0;

    //host send start signal    
    pinMode(DHT11PIN,OUTPUT);      //set pin to output 
    digitalWrite(DHT11PIN,LOW);    //set to low at least 18ms 
    delay(18);
    digitalWrite(DHT11PIN,HIGH);   //set to high 20-40us
    delayMicroseconds(40);

    //start recieve dht response
    pinMode(DHT11PIN,INPUT);       //set pin to input
    for(i=0;i<MAX_TIME;i++)         
    {
        counter=0;
        while(digitalRead(DHT11PIN)==lststate){     //read pin state to see if dht responsed. if dht always high for 255 + 1 times, break this while circle
            counter++;
            delayMicroseconds(1);
            if(counter==255)
                break;
        }
        lststate=digitalRead(DHT11PIN);    //read current state and store as last state. 
        if(counter==255)   //if dht always high for 255 + 1 times, break this for circle
            break;
 // top 3 transistions are ignored, maybe aim to wait for dht finish response signal
        if((i>=4)&&(i%2==0)){
            dht11_val[j/8]<<=1;     //write 1 bit to 0 by moving left (auto add 0)
            if(counter>16)      //long mean 1
                dht11_val[j/8]|=1;     //write 1 bit to 1 
            j++;
        }
    }
    // verify checksum and print the verified data
    if((j>=40)&&(dht11_val[4]==((dht11_val[0]+dht11_val[1]+dht11_val[2]+dht11_val[3])& 0xFF))){
        printf("RH:%d,TEMP:%d\n",dht11_val[0],dht11_val[2]);
        return 1;
    }
    else
        return 0;
}

int main(void){
    int attempts=ATTEMPTS;
    if(wiringPiSetup()==-1)
        exit(1);
    while(attempts){                        //you have 5 times to retry
        int success = dht11_read_val();     //get result including printing out
        if (success) {                      //if get result, quit program; if not, retry 5 times then quit
            break;
        }
        attempts--;
        delay(2500);  
  }
    return 0;
}

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