Digital Thermometer With Arduino & DS18B20

Simply create a digital thermometer with can tell you the current room temperature on a LCD screen. This is a beginners project.

Apparatus that you need:
1. Arduino UNO R3
2. DS18B20 temperature sensor.
3. 16X2 LCD display.
4. Connecting wires.
5. Project board. 

Now lets make digital thermometer.....


This is a Atmega168 pinouts for arduino. Just skip this if you wat to make this thermometer with your arduino.

Creating arduino on a breaboard is very easy. Now step by step wiring procedure is given below:
1. Pin 7  -> +5V
2. Pin8   -> GND
3. Pin9 -> Crystal -> 22pF capacitor -> GND
4. Pin10-> Crystal -> 22pF capacitor -> GND
5. pin 22 -> GND
6. Pin21 & Pin20 -> +5V
7. Pin1-> 10K registor to GND + Push button to +5V

Now you are ready.................

Connect the LCD with the atmega or arduino according to the default LCD example on the arduino IDE.

Now connect DS1307 DATA bus to the DIGITAL PIN 7 (Atmega pin 13)

#include <OneWireTempSensor.h>

#include <OneWire.h>
#include <LiquidCrystal.h>
int DS18S20_Pin = 7; //DS18S20 Signal pin on digital 7 by rahulmitra
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);
//Temperature chip i/o
OneWire ds(DS18S20_Pin); // on digital pin 7 by rahulmitra

void setup(void) {
Serial.begin(9600);
  lcd.begin(16, 2);
  // Print a message to the LCD.
  lcd.print("Rahul Mitra");
}

void loop(void) {
float temperature = getTemp();
Serial.println(temperature);
  lcd.setCursor(0, 1);
    lcd.print("Temp : ");
    lcd.print(temperature);
    lcd.print(" *C");
delay(100); //just here to slow down the output so it is easier to read

}

float getTemp(){
//returns the temperature from one DS18S20 in DEG Celsius

byte data[12];
byte addr[8];

if ( !ds.search(addr)) {
//no more sensors on chain, reset search
ds.reset_search();
return -1000;
}

if ( OneWire::crc8( addr, 7) != addr[7]) {
Serial.println("CRC is not valid!");
return -1000;
}

if ( addr[0] != 0x10 && addr[0] != 0x28) {
Serial.print("Device is not recognized");
return -1000;
}

ds.reset();
ds.select(addr);
ds.write(0x44,1); // start conversion, with parasite power on at the end

byte present = ds.reset();
ds.select(addr);
ds.write(0xBE); // Read Scratchpad


for (int i = 0; i < 9; i++) { // we need 9 bytes
data[i] = ds.read();
}

ds.reset_search();

byte MSB = data[1];
byte LSB = data[0];

float tempRead = ((MSB << 8) | LSB); //using two's compliment
float TemperatureSum = tempRead / 16;

return TemperatureSum;

}