Temperature Sensor – Introduction, Types and Interfacing with Arduino

Reading temperature using Arduino is a popular project amongst beginners.

Temperature measurement is very common and useful in many applications, including small household to huge industrial devices.

Generally, they are found in,

1. Automobiles
2. Computers
3. Home appliances
4. Medical devices
5. And more….

This sensor is responsible for maintaining the device’s temperature at a rated value, thereby assuring the system’s safety and long life.

Although I will say that temperature sensors are prevalent and quite necessary in engineering applications, it would help if you understand them in detail.

So in this article, we will start with the basics of temperature sensors, understand its types, and finally interfacing with Arduino.

Electronics beginners can do this project to measure the room temperature.

What is a Temperature Sensor?

It is a device that measures the surrounding temperature and converts that into the data understandable by the electronic devices. They work on the principle of resistance or voltage change in response to the temperature change.

A temperature sensor needs to be very precise and accurate to maintain the device’s temperature.

Types of Temperature Sensors

1. Contact Temperature Sensor

This type of temperature sensor is in direct contact with the material under observation. It works on the principle of Heat Conduction.

Useful in distinguishing solids, liquids, and gases over a broad scope of temperature.

2. Non-contact Temperature Sensor

This type of sensor helps determine the temperature of liquids and gases that radiates energy as the heat rises.

It works on the principle of convection and radiation.

Interfacing of Temperature Sensor with Arduino

We will be using PT100-S to illustrate the temperature sensor interfacing with Arduino.

What is PT100-S Temperature Sensor?

The PT100-S is a Thermistor that changes the resistance value in response to the surrounding temperature changes. It has good response time, accuracy, and repeatability.

The resistor is a strip of platinum with the resistance of 100-138.4 Ω.

It has gained the reputation for being useful in laboratories and industries to measure the temperature with excellent precision.

The PT100-S is equipped with a 316L stainless steel shield that makes it compatible with the temperature ranges up to 420°C.

PT100-S Connection with Arduino

Connecting PT100-S with Arduino will take only 5-10 minutes.

Note: Ensure you have connected everything properly before supplying power to the setup.

Follow the steps below,

Step 1 – Connect one end of the PT100-S temperature sensor to the analog pin on Arduino.

Step 2 – Now, we need to connect the same end of the sensor to 5V on Arduino through a resistor.

Note: Resistor is added here to avoid heating problems. You can calculate it using the formula below,

R2 = R1*1/(Vin/Vout-1)

The value of R2 should be low enough to avoid a low signal to noise ratio. Here we are using a 150Ω resistor in this project.

Step 3 – Connect the other end of the sensor to the “GND” pin on Arduino.

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Try keeping the PT100-S sensor near hot (candle) or cold (ice cube) material. You will see the change is readings.

Code

//Robu.in
#include <Wire.h> 

const int analogInPin = A5; //sensor connected to A5 pin

const int SensorValueLow = 463; 
const int SensorValueDiff = 36; // differance between high and low sensor value
const int TempValueDiff = 42; // differance between high and low Temp value
const int TempValueLow = 9;

int sensorValue = 0;
double Temp = 0;

void setup() 
{
}

void loop() 
{
  sensorValue = analogRead(analogInPin);
  Temp = sensorValue-SensorValueLow;
  Temp = Temp/SensorValueDiff;
  Temp = Temp*TempValueDiff;
  Temp = Temp+TempValueLow;

  Serial.print(sensorValue); //printing value of sensor on the serial monitor
  Serial.print(Temp); // printing temperature on the serial monitor

  delay(200); // interval of fetching data from sensor
}

Conclusion

Hope this article helped you to learn the basics of temperature sensor and interfacing with Arduino. If you have any doubts, then don’t forget to comment below.

Also, we will love to see the prototype of your project; temperature sensor interfacing with Arduino.

Note that all of the products used in this project are available at Robu.in. Do not forget to check them as well.

Sayonara!