Published December 2, 2022 © MIT

Arduino Temperature Display (With Thermistor)

This a quick, simple tutorial for building an Arduino temperature display, using a thermistor!

BeginnerFull instructions provided30 minutes1,060

Arduino Temperature Display (With Thermistor)

Things used in this project

Hardware components

Arduino Nano R3

10kΩ Thermistor

DFRobot I2C 16x2 Arduino LCD Display Module

Jumper wires (generic)

Resistor 10k ohm

Story

The Story

Hello!

When I am doing things, I always think "boy do I need a simple temperature display right now"! From checking the fridge temp, to the room temp, to outdoors, and even lake water temp, it seems I am always in need of this simple device! Well, I finally just built one, and I have decided to write this tutorial as a future reference for me, and for anyone who would like to build the same.

The Parts

For this project, I used only a couple basic components.

1x I2C LCD 16x2

1x Arduino Nano

1x 10kΩ thermistor

1x 10kΩ resistor

A length of wire

1x project box

1x USB cable for the Arduino nano

1x USB Battery Bank

Some rubber bands

Putting Everything Together

Since this project uses a low number of components, the wiring is very straightforward!

Here is a wiring description (schematic below):

LCD - Arduino:

VCC - +5V

GND - GND

SCL - A5

SDA - A4

Thermistor - Arduino:

First pin - +5V

Second pin - A0

10kΩ resistor - second pin to GND

That's all!

Here is a schematic:

Schematic

My thermistor is a very small DIP version that looks like this:

Very small thermistor

So... I soldered it to the end of a 24/2 wire that is about 3 feet long. This way, I can stick the sensor anywhere, like the freezer, or under water, without damaging the Arduino and display! This also means that the display stays visible at all times.

Thermistor (under red coating) soldered to end of cable

I hot glued everything into a small cardboard box, and cut a hole for the display in the top, a hole for the thermistor cable in the front, and a hole for plugging in the cable for powering the Arduino, on the right.

I then wrapped a rubber band around the battery and the box, with the box on top.

Bottom view

Top view

Here it is powered up, and reading the outside temperature (through a window) from inside!

Device on!

Calibrating the Thermistor

Make sure to calibrate your thermistor! To calibrate it, check the data sheet to your exact thermistor, and input the 3 resistance values for the 3 temperature values on this website:

https://thinksrs.com/downloads/programs/therm%20calc/ntccalibrator/ntccalculator.html

Copy and paste the A, B, and C values into the c1 , c2 , and c3 values at the beginning of the sketch.

Reference from this issue:

https://forum.arduino.cc/t/thermistor-slightly-wrong-values/1060825

Code

thermistor-with-lcd.ino

#include <LiquidCrystal_I2C.h>

#define thermistor A0

int Vo;
float R1 = 10000;
float logR2, R2, T;
float c1 = 1.009249522e-03, c2 = 2.378405444e-04, c3 = 2.019202697e-07;

LiquidCrystal_I2C lcd(0x27,16,2);
void setup() {
  pinMode(thermistor, INPUT);

  Serial.begin(9600);
  
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("Temperature: ");
}

void loop() {
  Vo = analogRead(thermistor);
  R2 = R1 * (1023.0 / (float)Vo - 1.0);
  logR2 = log(R2);
  T = (1.0 / (c1 + c2*logR2 + c3*logR2*logR2*logR2));
  T = T - 273.15;
  T = (T * 9.0)/ 5.0 + 32.0; 

  Serial.println("Temperature(F): " + String(T));
  
  lcd.setCursor(1,1);
  lcd.print(T);
  delay(500);
}

Credits

K Gray

23 projects • 23 followers

I love making things out of electronic components, coding in python and C++, designing PCBs and lots more.

Thanks to Circuit Basics.

Arduino Temperature Display (With Thermistor)

Things used in this project

Hardware components

Story

The Story

The Parts

Putting Everything Together

Calibrating the Thermistor

Schematics

Schematic

Code

thermistor-with-lcd.ino

GitHub Repository

Credits

K Gray

Comments

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Arduino Temperature Display (With Thermistor)

Arduino Temperature Display (With Thermistor)

Things used in this project

Hardware components

Story

The Story

The Parts

Putting Everything Together

Calibrating the Thermistor

Schematics

Schematic

Code

thermistor-with-lcd.ino

GitHub Repository

Credits

K Gray

Comments

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