DHT11 Arduino with VirtualWire

By some reason when using VirtualWire library and using vw_setup(2000) caused the readings from humidity sensor to fail (dht11 start condition 1 not met). I looked at datasheet and changed a the times how the MCU starts to talk with the sensor.

The code is based from this post

Here is the the fixed code:

void InitDHT() {
 pinMode(TEMP_RH_PIN, OUTPUT);
 delay(1000);
 digitalWrite(TEMP_RH_PIN,HIGH);
}

void ReadDHT() {

 bGlobalErr=0;
 byte dht_in;
 byte i;
        
        // see datasheet to understand this
        pinMode(TEMP_RH_PIN, OUTPUT);
        digitalWrite(TEMP_RH_PIN,HIGH);
        
 digitalWrite(TEMP_RH_PIN,LOW);
 delay(18);

 digitalWrite(TEMP_RH_PIN,HIGH);
 delayMicroseconds(22);

 pinMode(TEMP_RH_PIN,INPUT);
 delayMicroseconds(5);

 dht_in=digitalRead(TEMP_RH_PIN);

 if(dht_in) {
  bGlobalErr=1;
  Serial.println("<dht11 start condition 1 not met");
  return;
 }
 
 delayMicroseconds(80);
 dht_in=digitalRead(TEMP_RH_PIN);

 if(!dht_in) {
  bGlobalErr=2;
  Serial.println("<dht11 start condition 2 not met");
  return;
 }
 delayMicroseconds(80);
 
        //now ready for data reception... pick up the 5 bytes coming from the sensor
 for (i=0; i<5; i++)
    dht_dat[i] = read_dht_dat();

 //Next: restore pin to output duties
 pinMode(TEMP_RH_PIN,OUTPUT);
 digitalWrite(TEMP_RH_PIN,HIGH);

 byte dht_check_sum = dht_dat[0]+dht_dat[1]+dht_dat[2]+dht_dat[3];

 /*Condition in following "if" says "if fifth byte from sensor
       not the same as the sum of the first four..."*/
 if(dht_dat[4]!= dht_check_sum) {
   bGlobalErr=3;
          Serial.println("DHT11 checksum error");   
 }

}


byte read_dht_dat() {
 //Collect 8 bits from datastream, return them interpreted
 //as a byte. I.e. if 0000.0101 is sent, return decimal 5.
 //Code expects the system to have recently entered the
 //dataline low condition at the start of every data bit's
 //transmission BEFORE this function is called.
 byte i = 0;
 byte result=0;
 for (i=0; i< 8; i++) {
  //We enter this during the first start bit (low for 50uS) of the byte
  //Next: wait until pin goes high
  while(digitalRead(TEMP_RH_PIN)==LOW);
  delayMicroseconds(30);
  if (digitalRead(TEMP_RH_PIN)==HIGH)//Was: if(PINC & _BV(dht_PIN))
  result |=(1<<(7-i));
  while (digitalRead(TEMP_RH_PIN)==HIGH);
  //Was: while((PINC & _BV(dht_PIN)));
 }
 //end of "for.."
 return result;
}