Grove_Temperature_And_Humidity_Sensor/examples/DHTtester/DHTtester.ino

// Example testing sketch for various DHT humidity/temperature sensors
// Written by ladyada, public domain

#include "DHT.h"

#define DHTPIN A0     // what pin we're connected to

// Uncomment whatever type you're using!
//#define DHTTYPE DHT11   // DHT 11 
#define DHTTYPE DHT22   // DHT 22  (AM2302)
//#define DHTTYPE DHT21   // DHT 21 (AM2301)

// Connect pin 1 (on the left) of the sensor to +5V
// Connect pin 2 of the sensor to whatever your DHTPIN is
// Connect pin 4 (on the right) of the sensor to GROUND
// Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor

DHT dht(DHTPIN, DHTTYPE);

void setup() 
{
    Serial.begin(9600); 
    Serial.println("DHTxx test!");

    dht.begin();
}

void loop() 
{
    // Reading temperature or humidity takes about 250 milliseconds!
    // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
    float h = dht.readHumidity();
    float t = dht.readTemperature();

    // check if returns are valid, if they are NaN (not a number) then something went wrong!
    if (isnan(t) || isnan(h)) 
    {
        Serial.println("Failed to read from DHT");
    } 
    else 
    {
        Serial.print("Humidity: "); 
        Serial.print(h);
        Serial.print(" %\t");
        Serial.print("Temperature: "); 
        Serial.print(t);
        Serial.println(" *C");
    }
}