added hardware specifications

hardware/tests/dht22/dht22.ino

@@ -0,0 +1,40 @@
+/* How to use the DHT-22 sensor with Arduino uno
+   Temperature and humidity sensor
+*/
+
+//Libraries
+#include <DHT.h>
+
+//Constants
+#define DHTPIN 2     // what pin we're connected to
+#define DHTTYPE DHT22   // DHT 22  (AM2302)
+DHT dht(DHTPIN, DHTTYPE); //// Initialize DHT sensor for normal 16mhz Arduino
+
+
+//Variables
+int chk;
+float hum;  //Stores humidity value
+float temp; //Stores temperature value
+
+void setup()
+{
+  Serial.begin(9600);
+  dht.begin();
+}
+
+void loop()
+{
+    delay(2000);
+    //Read data and store it to variables hum and temp
+    hum = dht.readHumidity();
+    temp= dht.readTemperature();
+    //Print temp and humidity values to serial monitor
+    Serial.print("Humidity: ");
+    Serial.print(hum);
+    Serial.print(" %, Temp: ");
+    Serial.print(temp);
+    Serial.println(" Celsius");
+    delay(10000); //Delay 2 sec.
+}
+
+