树莓派使用DHT11测温湿度 C语言教程

树莓派读取 DHT11 温湿度传感器温湿度数值。常用的四种方法，1.系统功能直读、2.使用Adafruit库读取、3.用Python 编程来读取、4.C语言编程读取， 本次教程主要使用C语言读取。

工作电压：3.3v-5v

检测温度范围：±5%RH (0~50°C)

检测湿度范围：1%RH（20%RH ~ 90%RH (25°C)

在开始之前务必先给系统安装好wiringPi库，如果你的树莓派系统还没有安装wiringPi库，可参考这个教程➦树莓派安装wiringPi库

一：硬件连接

二：C程序代码

输入命令 新建一个dht11.c程序文件。

sudo nano dht11.c

#derived from raspi.cc
#include <wiringPi.h>
#include <stdio.h>
#include <stdlib.h>
 
typedef unsigned char uint8;
typedef unsigned int  uint16;
typedef unsigned long uint32;
 
#define HIGH_TIME 32
 
int pinNumber = 7;
uint32 databuf;
  
uint8 readSensorData(void)
{
    uint8 crc; 
    uint8 i;
  
    pinMode(pinNumber, OUTPUT); // set mode to output
    digitalWrite(pinNumber, 0); // output a high level 
    delay(25);
    digitalWrite(pinNumber, 1); // output a low level 
    pinMode(pinNumber, INPUT); // set mode to input
    pullUpDnControl(pinNumber, PUD_UP);
 
    delayMicroseconds(27);
    if (digitalRead(pinNumber) == 0) //SENSOR ANS
    {
        while (!digitalRead(pinNumber))
            ; //wait to high
 
        for (i = 0; i < 32; i++)
        {
            while (digitalRead(pinNumber))
                ; //data clock start
            while (!digitalRead(pinNumber))
                ; //data start
            delayMicroseconds(HIGH_TIME);
            databuf *= 2;
            if (digitalRead(pinNumber) == 1) //1
            {
                databuf++;
            }
        }
 
        for (i = 0; i < 8; i++)
        {
            while (digitalRead(pinNumber))
                ; //data clock start
            while (!digitalRead(pinNumber))
                ; //data start
            delayMicroseconds(HIGH_TIME);
            crc *= 2;  
            if (digitalRead(pinNumber) == 1) //1
            {
                crc++;
            }
        }
        return 1;
    }
    else
    {
        return 0;
    }
}
  
int main(void)
{
    printf("PIN:%d\n", pinNumber);
 
    if (-1 == wiringPiSetup()) {
        printf("Setup wiringPi failed!");
        return 1;
    }
  
    pinMode(pinNumber, OUTPUT); // set mode to output
    digitalWrite(pinNumber, 1); // output a high level 
 
    printf("Starting...\n");
    while (1) 
    {
        pinMode(pinNumber, OUTPUT); // set mode to output
        digitalWrite(pinNumber, 1); // output a high level 
        delay(3000);
        if (readSensorData())
        {
            printf("Sensor data read ok!\n");
            printf("RH:%d.%d\n", (databuf >> 24) & 0xff, (databuf >> 16) & 0xff); 
            printf("TMP:%d.%d\n", (databuf >> 8) & 0xff, databuf & 0xff);
            databuf = 0;
        }
        else
        {
            printf("Sensor dosent ans!\n");
            databuf = 0;
        }
    }
    return 0;
}

然后编译程序

gcc -Wall -o dht11 dht11.c -lwiringPi

sudo ./dht11

查看效果如下：湿度74%  温度34.2摄氏度