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.

Step 1: Make Arduino on Breadboard.

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.................

Step 2: Connecting LCD

Step 3: Connecting DS18B20 Temperature Sensor

Step 4: Preparing the Circuit.

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)

Step 5: Arduino CODE

#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;

}