Raspberry Pi DHT11 temperature and humidity sensor

Github:https://github.com/hicrater/raspberry-dht11-temperature.git

First, look at the wiring

Wiring diagram

Vcc	Cathode	Pick up the Raspberry Pi 3.3v power supply (choose one on the line)
GND	Negative	Pick up the Raspberry Pi ground (just choose one).
Out	Data cable	Pick Up Raspberry Pi GPIO7

Ii. Attaching the information of DHT11  

Third, the Code

#include <wiringPi.h>#include<stdio.h>#include<stdlib.h>#include<stdint.h>#defineMax_time 85#defineGpioport 7//Store the Read dataintdht11_val[5] = {0,0,0,0,0 };//This function reads the temperature valueintDht11_read_val () {uint8_t lststate= high;//High in wiringPi.h defined as 1uint8_t counter =0;//counteruint8_t j =0, I;//Initializes an array of 0 for(i =0; I <5; i++) Dht11_val[i]=0;//Send start SignalPinmode (Gpioport, OUTPUT);//set Gpio to outputDigitalwrite (Gpioport, low);//keep low level at least 18msDelay -);d igitalwrite (Gpioport, high);//keep High Level 20-40usDelaymicroseconds ( +);//start receiving DHT response signalsPinmode (Gpioport, INPUT);//set Gpio as input//start waiting for temperature sensor response (will pull down the data cable when responding to the data sheet temperature sensor) for(i =0; i < max_time; i++) {counter=0; while(Digitalread (gpioport) = = lststate) {//If the current level is equal at this point, the level does not change, so continue waiting for the next cyclecounter++;d Elaymicroseconds (1);if(Counter = =255)//If the temperature sensor has not changed the data line after the cycle of the 255+1 time, exit this cycle Break;} Lststate= Digitalread (Gpioport);//read the latest state value of the data lineif(Counter = =255)//If the temperature sensor has not changed the data line after the cycle of the 255+1 time, exit this cycle Break;//The first three times being ignored may be in response to a temperature sensor (this thing is not as fast as the data sheet says) .... )if((I >=4) && (i%2==0)){//the 2 remainder is because the even level is used to transmit data (as can be seen from the data sheet)Dht11_val[j/8] <<=1;//Move left one (at this point the last one is 0)if(Counter > -)//the time here is very long, which means 1 here .Dht11_val[j/8] |=1;//writes data 1 toJ + +;}}/*Start processing data 1. Because a complete data output is 40 bits, J should be greater than 402.dht11_val[4] for checksum, here to determine if the checksum is correct 3. Print only dht11_val[0], dht11_val[2] because dht11_val[ 1], dht11_val[3] is a fractional part, according to the data sheet decimal is always zero*/if(J >= +) && (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;}Elsereturn 0;}intMainvoid){//repeat 5 times to tryintAttempts =5;//Initialize Gpioif(Wiringpisetup () = =-1) Exit (1);//make 5 attempts while(attempts) {//Get temperature ValueintSuccess =dht11_read_val ();//exit after getting successfulif(Success) Break; attempts--;d Elay (2500);}return 0;}

Iv. Final Effect

Raspberry Pi DHT11 temperature and humidity sensor