Other Arduino Codes and Videos by Robojax

Arduino code and video for DHT22 Temperature and Humidity Sensor

This is the Arduino code and video for DHT22 Temprerature and Humidity Sensor Module

The actual sensor is AM2302 from AOSONG Chine. This video shows you how to use DHT22 to measure Temperature, humidity and disply in serial monitor or use for other perpose.

To use 2 or more DHT22 or DHT11 sensors see This page.


 /*
 * This is the Arduino code for  DHT22 module to read temprature and humidity
 * This code can display temprature in:
 * getTemp("c") is used to get Celsius
 * getTemp("f") is used to get fahrenheit
 * getTemp("k") is used for Kelvin
 * getTemp("hif") is used to get fahrenheit
 * getTemp("hic") is used to get Celsius
 * getTemp("f") is used to get humidity 
 * Watch the video https://youtu.be/oi_GPSLjgBY
  * Other Arduino libarary and videos http://robojax.com/learn/arduino/
 *  * 
 * Written/updated by Ahmad Shamshiri for Robojax.com Video
 * Date: Jan 08, 2018, in Ajax, Ontario, Canada
 * Permission granted to share this code given that this
 * note is kept with the code.
 * Disclaimer: this code is "AS IS" and for educational purpose only.
 * 
 * original source code : https://github.com/adafruit/DHT-sensor-library
 */

// 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 Robojax test!");

  dht.begin();
}

void loop() {
  // Wait a few seconds between measurements.
  delay(2000);


  // Robojax.com test video
  Serial.print("Temperature: ");
  
  Serial.print(getTemp("c"));
  
  Serial.print(" *C ");
  Serial.print(getTemp("f"));
  Serial.println (" *F");
  Serial.println("-----------------");  
  Serial.print("Heat index: ");
  Serial.print(getTemp("hic"));
  Serial.print(" *C ");
  Serial.print(getTemp("hif"));
  Serial.println(" *F");
  Serial.print(getTemp("k"));
  Serial.println(" *K");
  Serial.println("-----------------");    
  Serial.print("Humidity: ");
  Serial.print(getTemp("h"));
  Serial.println(" % ");
  Serial.println("===========================");
}


/*
 * getTemp(String req)
 * returns the temprature related parameters
 * req is string request
 * This code can display temprature in:
 * getTemp("c") is used to get Celsius
 * getTemp("f") is used to get fahrenheit
 * getTemp("k") is used for Kelvin
 * getTemp("hif") is used to get fahrenheit
 * getTemp("hic") is used to get Celsius
 * getTemp("f") is used to get humidity 
 */
float getTemp(String req)
{

  // 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);

  // 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);

  // 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 Kelvin 
  float k = t + 273.15;
  if(req =="c"){
    return t;//return Cilsus
  }else if(req =="f"){
    return f;// return Fahrenheit
  }else if(req =="h"){
    return h;// return humidity
  }else if(req =="hif"){
    return hif;// return heat index in Fahrenheit
  }else if(req =="hic"){
    return hic;// return heat index in Cilsus
  }else if(req =="k"){
    return k;// return temprature in Kelvin
  }else{
    return 0.000;// if no reqest found, retun 0.000
  }
 
}

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