Arduino and AM2302 (DHT22) on a Mini Breadboard

The AM2302 (also known by DHT-22) is a low cost humidity and temperature sensor with a single wire digital interface. The sensor is calibrated and doesn’t require extra components so you can get right to measuring relative humidity and temperature. The AM2302 can connect directly to the Arduino Uno.

The AM2302(DHT22) temperature / humidity sensor cables are as follows:

Red : +5v power connects to 5v power on Arduino Uno

Yellow : Data connection connects to Pin 2 or 3 on Arduino Uno

Black : Supplementary ground can connect to a GND on Arduino Uno

Documentation says it is not necessary and can be left out, White : Full ground connects to a GND on Arduino Uno

The major limitation is that the sensor can not take readings more rapidly than every 2 seconds.

On the Arduino sketch, there is a 3 second delay between readings to ensure precision.

Arduino Sketch: Direct link

	/*
	AM2302 Temperature / Humidity Sensor (DHT22)
	Current Code
	Created by Derek Erb 30/01/2013
	Modified 30/01/2013
	Requirement : Arduino + AM2302 sensor connected to pin 2
	DHT Library from:
	https://github.com/adafruit/DHT-sensor-library
	v0.03 Delays and formatting
	v0.02 Delay 3 seconds between readings
	*/
	#include "DHT.h" // DHT & AM2302 library
	// Version number
	const float fVerNum = 0.03;
	// Data pin connected to AM2302
	#define DHTPIN 2
	#define DHTTYPE DHT22 // DHT 22 (AM2302)
	DHT dht(DHTPIN, DHTTYPE); // LED pins
	//////////////////////////////////////////////////////
	//
	// SETUP
	//
	void setup() {
	// Setup serial monitor
	Serial.begin(9600);
	// Wait 3 seconds
	delay(3000);
	Serial.println(F("\nAM2302 Sensor"));
	Serial.print(F("Version : "));
	Serial.println(fVerNum);
	Serial.println(F("Arduino - Derek Erb\n"));
	delay(5000);
	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(F("Failed to read from DHT"));
	}
	else {
	Serial.print(F("Humidity: "));
	Serial.print(h);
	Serial.print(F(" %\t"));
	Serial.print(F("Temperature: "));
	Serial.print(t);
	Serial.println(F(" C"));
	}
	// Wait 3 seconds
	delay(3000);
	}

view raw gistfile1.ino hosted with by GitHub

This project has been taken from Fritzing.org.

This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.