온습도 측정하기 - DHT22 센서이용

DHT11 센서 업그레이드 버전인 DHT22 센서로 테스트 해보았습니다.

DHT11은 파란색인데 DHT22는 흰색 케이스이네요. 

DHT 센서용 라이브러리를 찾아보니 종류가 여러가지가 있더군요.

그런데 아래 라이브러리가 Heat Index 출력 기능이 있네요. 이게 뭔가 찾아보니 대략 체감 온도 같습니다.

https://github.com/adafruit/DHT-sensor-library

센서 핀에 표시가 없네요. 왼쪽부터 1번핀이 5V이고 2번핀이 데이타핀으로 5V와 10K 저항을 연결해줍니다. 

3번핀은 연결안하고 4번핀을 GND에 연결해줍니다.

// Example testing sketch for various DHT humidity/temperature sensors

// Written by ladyada, public domain

#include "DHT.h"

#define DHTPIN 5     // 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

// 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");

}