Arduino and DS18B20 Temperature Controlling Example

 A temperature controller can be found anywhere in the market at low cost. However we can create it one using an analog circuit, or even a programmable device. Here I create an Arduino-based temperature controller using some components:

1. An Arduino Uno board
2. A DS18B20 temperature sensor
3. A 5V relay module
4. A character LCD with some other components and accessary.

Circuit prototyping on breadboard

The controller request and get temperature data from DS18B20 in degree Celsius. The display show either Celsius and degree Fahrenheit. It updates the data for every 5 seconds. I set in program for a condition for the temperature above 30 degree Celsius. Whenever it's true an output relay connects to pin 13 will turn on.

Schematic Diagram

I use DallasTemperature.h file due to its simplicity. 

#include <OneWire.h>
#include <DallasTemperature.h>
#include <LiquidCrystal.h>
 
//LCD Connection RS EN D4...D7
LiquidCrystal lcd(7,8,9,10,11,12);
 
OneWire oneWire(4);
 
DallasTemperature sensors(&oneWire);
 
//Relay Output Pin
const int relay=13;
 
void setup(){
  pinMode(relay,OUTPUT);
  //Start up the 1-Wire Library
  sensors.begin();
  lcd.begin(16,2);
  lcd.print("ds18B20 Example");
  delay(3000);
  lcd.clear();
}
 
float getC,getF;
 
void loop(){
  //Send the command to get Temperature
  sensors.requestTemperatures();
  getC=sensors.getTempCByIndex(0);
  getF=DallasTemperature::toFahrenheit(getC);
 
  if(int(getC)>=30) digitalWrite(relay,HIGH);
  else digitalWrite(relay,LOW);
 
  lcd.home();
  lcd.print("Temperature: ");
  lcd.setCursor(0,1);
  lcd.print(String(getC,1)+char(223)+"C"+" "+String(getF,1)+char(223)+"F");
  delay(5000);
}

Click here to download its source file.