Sample code for the DHT-22 temperature and humidity sensor in arduino.
Code borrowed from this Instructable, a useful guide to using the sensor.
Second code block includes temperature in Fahrenheit and comes from the Adafruit sensor library.
/* How to use the DHT-22 sensor with Arduino uno Temperature and humidity sensor More info: http://www.ardumotive.com/how-to-use-dht-22-sensor-en.html Dev: Michalis Vasilakis // Date: 1/7/2015 // www.ardumotive.com */ //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() { //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(2000); //Delay 2 sec. }
#include <Adafruit_Sensor.h> #include <Adafruit_LIS3DH.h> // Example testing sketch for various DHT humidity/temperature sensors // Written by ladyada, public domain #include "DHT.h" #define DHTPIN 2 // what digital pin we're connected to // Uncomment whatever type you're using! //#define DHTTYPE DHT11 // DHT 11 #define DHTTYPE DHT22 // DHT 22 (AM2302), AM2321 //#define DHTTYPE DHT21 // DHT 21 (AM2301) // Connect pin 1 (on the left) of the sensor to +5V // NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1 // to 3.3V instead of 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 // Initialize DHT sensor. // Note that older versions of this library took an optional third parameter to // tweak the timings for faster processors. This parameter is no longer needed // as the current DHT reading algorithm adjusts itself to work on faster procs. DHT dht(DHTPIN, DHTTYPE); void setup() { Serial.begin(9600); Serial.println("DHTxx test!"); dht.begin(); } void loop() { // Wait a few seconds between measurements. delay(2000); // 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(); // Read temperature as Celsius (the default) float t = dht.readTemperature(); // Read temperature as Fahrenheit (isFahrenheit = true) float f = dht.readTemperature(true); // Check if any reads failed and exit early (to try again). if (isnan(h) || isnan(t) || isnan(f)) { Serial.println("Failed to read from DHT sensor!"); return; } // Compute heat index in Fahrenheit (the default) float hif = dht.computeHeatIndex(f, h); // Compute heat index in Celsius (isFahreheit = false) float hic = dht.computeHeatIndex(t, h, false); Serial.print("Humidity: "); Serial.print(h); Serial.print(" %\t"); Serial.print("Temperature: "); Serial.print(t); Serial.print(" *C "); Serial.print(f); Serial.print(" *F\t"); Serial.print("Heat index: "); Serial.print(hic); Serial.print(" *C "); Serial.print(hif); Serial.println(" *F"); }