//

//mydht11.c

//

#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 =;  //use gpio1 to read data

uint32 databuf;

uint8 readSensorData(void)

{

    uint8 crc;

    uint8 i;

    pinMode(pinNumber,OUTPUT); // set mode to output

    digitalWrite(pinNumber, ); // output a high level

    delay();

    digitalWrite(pinNumber, ); // output a low level

    pinMode(pinNumber, INPUT); // set mode to input

    pullUpDnControl(pinNumber,PUD_UP);

    delayMicroseconds();

    if(digitalRead(pinNumber)==) //SENSOR ANS

       {

         while(!digitalRead(pinNumber)); //wait to high

      for(i=;i<;i++)

       {

       while(digitalRead(pinNumber)); //data clock start

       while(!digitalRead(pinNumber)); //data start

          delayMicroseconds(HIGH_TIME);

          databuf*=;

           if(digitalRead(pinNumber)==) //

            {

                databuf++;

            }

        }

      for(i=;i<;i++)

       {

       while(digitalRead(pinNumber)); //data clock start

       while(!digitalRead(pinNumber)); //data start

          delayMicroseconds(HIGH_TIME);

          crc*=;

          if(digitalRead(pinNumber)==) //

           {

                crc++;

           }

        }

    return ;

       }

   else

        {

        return ;

         }

}

int main (void)

{

  printf("Use GPIO1 to read data!\n");

  if (- == wiringPiSetup()) {

    printf("Setup wiringPi failed!");

    return ;

  }

  pinMode(pinNumber, OUTPUT); // set mode to output

  digitalWrite(pinNumber, ); // output a high level 

  printf("Enter OS-------\n");

  while() {

    pinMode(pinNumber,OUTPUT); // set mode to output

    digitalWrite(pinNumber, ); // output a high level

    delay();

    if(readSensorData())

    {

       printf("Congratulations ! Sensor data read ok!\n");

       printf("RH:%d.%d\n",(databuf>>)&0xff,(databuf>>)&0xff);

       printf("TMP:%d.%d\n",(databuf>>)&0xff,databuf&0xff);

       databuf=;

     }

    else

     {

        printf("Sorry! Sensor dosent ans!\n");

       databuf=;

      }

  }

  return ;

}

//dht11.c 
#include <wiringPi.h>

#include <stdio.h>

#include <stdlib.h>

#include <stdint.h>

#define MAX_TIME 85

#define DHT11PIN 1

#define ATTEMPTS 5                 //retry 5 times when no response

int dht11_val[]={,,,,};

int dht11_read_val(){

    uint8_t lststate=HIGH;         //last state

    uint8_t counter=;

    uint8_t j=,i;

    for(i=;i<;i++)

        dht11_val[i]=;

    //host send start signal

    pinMode(DHT11PIN,OUTPUT);      //set pin to output

    digitalWrite(DHT11PIN,LOW);    //set to low at least 18ms

    delay();

    digitalWrite(DHT11PIN,HIGH);   //set to high 20-40us

    delayMicroseconds();

    //start recieve dht response

    pinMode(DHT11PIN,INPUT);       //set pin to input

    for(i=;i<MAX_TIME;i++)

    {

        counter=;

        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();

            if(counter==)

                break;

        }

        lststate=digitalRead(DHT11PIN);             //read current state and store as last state.

        if(counter==)                            //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>=)&&(i%==)){

            dht11_val[j/]<<=;                     //write 1 bit to 0 by moving left (auto add 0)

            if(counter>)                          //long mean 1

                dht11_val[j/]|=;                  //write 1 bit to 1

            j++;

        }

    }

    // verify checksum and print the verified data

    if((j>=)&&(dht11_val[]==((dht11_val[]+dht11_val[]+dht11_val[]+dht11_val[])& 0xFF))){

        printf("RH:%d,TEMP:%d\n",dht11_val[],dht11_val[]);

        return ;

    }

    else

        return ;

}

int main(void){

    int attempts=ATTEMPTS;

    if(wiringPiSetup()==-)

        exit();

    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();

    }

    return ;

}