新建并打开C文件

touch dht11.c

sudo vim dht11.c

编写驱动程序

 1 #include<wiringPi.h>
 2 #include<stdio.h>
 3 #include<stdlib.h>
 4 #include<stdint.h>
 5 #define MAX_TIME 85
 6 #define DHT11PIN 7
 7 #define ATTEMPTS 5                 //retry 5 times when no response
 8 int dht11_val[5]={0,0,0,0,0};
 9
10 int dht11_read_val(){
11     uint8_t lststate=HIGH;         //last state
12     uint8_t counter=0;
13     uint8_t j=0,i;
14     for(i=0;i<5;i++)
15         dht11_val[i]=0;
16
17     //host send start signal
18     pinMode(DHT11PIN,OUTPUT);      //set pin to output
19     digitalWrite(DHT11PIN,LOW);    //set to low at least 18ms
20     delay(18);
21     digitalWrite(DHT11PIN,HIGH);   //set to high 20-40us
22     delayMicroseconds(40);
23
24     //start recieve dht response
25     pinMode(DHT11PIN,INPUT);       //set pin to input
26     for(i=0;i<MAX_TIME;i++)
27     {
28         counter=0;
29         while(digitalRead(DHT11PIN)==lststate){     //read pin state to see if dht responsed. if dht always high for 255 + 1 times, break this while circle
30             counter++;
31             delayMicroseconds(1);
32             if(counter==255)
33                 break;
34         }
35         lststate=digitalRead(DHT11PIN);    //read current state and store as last state.
36         if(counter==255)   //if dht always high for 255 + 1 times, break this for circle
37             break;
38  // top 3 transistions are ignored, maybe aim to wait for dht finish response signal
39         if((i>=4)&&(i%2==0)){
40             dht11_val[j/8]<<=1;     //write 1 bit to 0 by moving left (auto add 0)
41             if(counter>16)      //long mean 1
42                 dht11_val[j/8]|=1;     //write 1 bit to 1
43             j++;
44         }
45     }
46     // verify checksum and print the verified data
47     if((j>=40)&&(dht11_val[4]==((dht11_val[0]+dht11_val[1]+dht11_val[2]+dht11_val[3])& 0xFF))){
48         printf("RH:%d,TEMP:%d\n",dht11_val[0],dht11_val[2]);
49         return 1;
50     }
51     else
52         return 0;
53 }
54
55 int main(void){
56     int attempts=ATTEMPTS;
57     if(wiringPiSetup()==-1)
58         exit(1);
59     while(attempts){                        //you have 5 times to retry
60         int success = dht11_read_val();     //get result including printing out
61         if (success) {                      //if get result, quit program; if not, retry 5 times then quit
62             break;
63         }
64         attempts--;
65         delay(2500);
66   }
67     return 0;
68 }

按esc，然后输入:wq保存退出。

编译c文件

需安装wiringPi开发库，安装教程详见本博主博客：树莓派安装wiringPi开发库

输入命令：

gcc -Wall -o dht11 dht11.c -lwiringPi

1

gcc是编译器，-Wall是在编译时显示警告信息，-o dht11.c是将dht11.c文件编译成文件名为dht11的可执行文件，-lwiringPi是将wiringPi头文件包含在可执行文件中。

运行程序

输入命令：

sudo ./dht11

可以看到湿度和温度值都正确的打印在了屏幕上。