DHT11 Temperature and Humidity Sensor.

The DHT11 sensor includes a resistive-type humidity measurement component, with an NTC temperature measurement component, and a high-performance 8-bit microcontroller inside, and provides calibrated digital signal output.  It has high reliability and excellent long-term stability, thanks to the exclusive digital signal acquisition technique and temperature & humidity sensing technology.

Each DHT11 is strictly calibrated in the laboratory which is extremely accurate in humidity calibration. The calibration coefficients are stored as a program in the OTP memory, which is used by the sensor’s internal signal detecting process. The single-wire serial interface makes system integration quick and easy. Its small size, low power consumption, and up-to-20 meter signal transmission make it the best choice for various applications, including those most demanding ones.

DHT11 Temperature and Humidity Sensor Specification:

Power Supply： 3.3~5.5V DC
Output： 3 pin single row
Measurement Range： Humidity 20-90%RH， Temperature  0~50℃
Accuracy： Humidity +-5%RH， Temperature +-2℃
Resolution： Humidity  1%RH， Temperature  1℃
Interchangeability： Fully Interchangeable
Long-Term Stability： <±1%RH/year

Library: DHT.zip

Sketch

#include <dht.h>

#define dht_dpin A0 //no ; here. Set equal to channel sensor is on

dht DHT;

void setup(){
 Serial.begin(9600);
 delay(300);//Let system settle
 Serial.println("Humidity and temperaturenn");
 delay(700);//Wait rest of 1000ms recommended delay before
 //accessing sensor
}//end "setup()"

void loop(){
 //This is the "heart" of the program.
 DHT.read11(dht_dpin);

 Serial.print("Current humidity = ");
 Serial.print(DHT.humidity);
 Serial.print("% ");
 Serial.print("temperature = ");
 Serial.print(DHT.temperature); 
 Serial.println("C ");
 delay(800);//Don't try to access too frequently... in theory
 //should be once per two seconds, fastest,
 //but seems to work after 0.8 second.
}// end loop()