Introduction: DS18B20 Temperature Probe With LCD

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About: Hello, My name is Samuel, I am a student. I love micro controllers like arduino, they are my favorite interest. I also do geocaching, a worldwide treasure hunt game. I hope you enjoy my instructables! Samuel

The DS18B20 comes in a temperature probe form, which is waterproof. I had a real hard time trying to get this one working and I thought I would share how I in the end got it working. Enjoy!

Step 1: Parts

The parts you will need for this project:

Arduino Mega or other arduino (3-15$)

An LCD (around 3$)

A DS18B20 temperature probe (I got this for about 2$)

A couple of jumper wires (Around 3$)

A 4.7K resistor (Don't exactly know, I got a pack of 600 resistors with different types for 3$)

A 220 Ohm resitor for the LCD (Again, I don't exactly know, as I got a pack of 600 resistors with different types for 3$)

Step 2: Connections (without LCD)

The way I am going to put this is first by using only the DS18B20 sensor and print the results to the serial monitor in case you don't have a LCD or just want to test your sensor.

Next I am going to show you how to connect the LCD as well.

So for the DS18B20:

You have to connect this as the picture intends. You will have to connect:

VCC -> Arduino 5V, plus a 4.7K resistor going from VCC to Data

Data -> Any arduino pin

GND -> Arduino GND


Step 3: Code (without LCD)

Here is the code for the sensor without LCD, I am using two extra libraries:

DallasTemperature,

OneWire

Enjoy:

#include <OneWire.h>
#include <DallasTemperature.h>
#define ONE_WIRE_BUS 7
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
float tempC = 0;
float tempF = 0;
void setup() {
  sensors.begin();
  pinMode(3, OUTPUT);
  analogWrite(3, 0);
  Serial.begin(9600);
  
}
void loop() {
  sensors.requestTemperatures();
  tempC = sensors.getTempCByIndex(0);
  tempF = sensors.toFahrenheit(tempC);
  delay(1000);
  
  Serial.print("C: ");
  Serial.print(tempC);
  Serial.print("   F: ");
  Serial.println(tempF);
}

Step 4: Connections (with LCD)

If you are going to connect the LCD, connect it like this:

I am going to connect the wire which should go to a potentiometer to control the contrast to pin 3 on arduino.

Connections: (LCD -> ARDUINO)
Pin 1 -> GND

Pin 2 -> VCC

Pin 3 -> Arduino pin 3

Pin 4 -> Arduino pin 33

Pin 5 -> GND

Pin 6 -> Arduino pin 31

Pin 7 - 10 -> NONE

Pin 11 -> Arduino pin 22

Pin 12 -> Arduino pin 24

Pin 13 -> Arduino pin 26

Pin 14 -> Arduino pin 28

Pin 15 -> VCC through 220 OHM resistor.

Pin 16 -> GND

Step 5: Code (with LCD)

Here is the code for the LCD, remember to hook everything up right, and then this will work like a charm up to 125 degrees. And if your display only shows -127 degrees, then it is probably the resistor to the temp sensor not hooked up right.

I am using two extra libraries:

DallasTemperature,

OneWire

Here is the code, enjoy:

#include <OneWire.h>
#include <LiquidCrystal.h>
#include <DallasTemperature.h>

#define ONE_WIRE_BUS 7
OneWire oneWire(ONE_WIRE_BUS);
DallasTemperature sensors(&oneWire);
float tempC = 0;
float tempF = 0;
LiquidCrystal lcd(33,31,22,24,26,28);
void setup() {
  sensors.begin();
  lcd.begin(16,2);
  lcd.clear();
  pinMode(3, OUTPUT);
  analogWrite(3, 0);
  Serial.begin(9600);
  
}
void loop() {
  sensors.requestTemperatures();
  tempC = sensors.getTempCByIndex(0);
  tempF = sensors.toFahrenheit(tempC);
  delay(1000);
  
  Serial.println(tempC);
  lcd.setCursor(0,0);
  lcd.print("C: ");
  lcd.print(tempC);
  lcd.print(" degrees");
  lcd.setCursor(0,1);
  lcd.print("F: ");
  lcd.print(tempF);
  lcd.print(" degrees");
}

Step 6: Proof of Working and End/finish

I have measured temperature up to 100 degrees with this sensor and it works very well. Take a look at the pictures and you will see when it is at about 99 degrees Celsius. The only downside is that when the display gets up to more than a hundred degrees fahrenheit, the S gets cut off, which is kind of unfortunate, although you can fix this by adding a lcd.clear(); at the end of the code above the semi-colon.

Thanks for reading this tutorial and I hope it will help you in connecting your DS18B20. If you liked this tutorial, please subscribe for more and give it a favourite.

Samuel