Lesson 8 Thermistor

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Introduction

A thermistor is a type of resistor whose resistance varies significantly with temperature.

Components

– 1 * SunFounder Uno board

– 1 * USB data cable

– 1 * Thermistor

– 1 * Resistor (10K)

– Several jumper wires

Experimental Principle

The resistance of the thermistor varies significantly with ambient temperature. It can detect surrounding temperature changes in real time. Send the temperature data to analog I/O port of SunFounder. Next we only need to convert sensor output to Celsius temperature by simple programming and display it on the serial port.

Experimental Procedures

Step 1: Build the circuit

The schematic diagram

Step 2: Program (Please refer to the example code in LEARN -> Get Tutorial on our website)

Step 3: Compile the code

Step 4: Upload the sketch to the SunFounder Uno board

Now, you can see current temperature displayed on the serial monitor.

Code

/************************************
* name:thermistor
* function:you can see current temperature displayed on the serial monitor.
**************************************/
//Email: support@sunfounder.com
//Website: www.sunfounder.com#define analogPin A0 //the thermistor attach to
#define beta 4090 //the beta of the thermistor
#define resistance 10 //the value of the pull-down resistorvoid setup()
{
  Serial.begin(9600);
}void loop()
{
  //read thermistor value
  long a = analogRead(analogPin);
  //the calculating formula of temperature
  float tempC = beta /(log((1025.0 * 10 / a – 10) / 10) + beta / 298.0) – 273.0;
  //float tempF = 1.8*tempC + 32.0;//convert centigrade to Fahrenheit
  Serial.print(“TempC: “);//print” TempC: “
  Serial.print(tempC);//print Celsius temperature
  Serial.print(” C”);//print the unit
  Serial.println();
  //Serial.print(“TempF: “);
  // Serial.print(tempF);
  // Serial.print(” F”);
  delay(200); //wait for 200 milliseconds
}

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