# Arduino: Project 19: Temperature Sensor

Hello everyone!! Welcome to this post on Arduino Projects!!
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Check out the breadboard intro right HERE

In this project I’ve used a Thermistor (a resistor whose resistance varies with temperature) to build a temperature sensor

Demo:

So this is what my project turned out to be:

Things Required:

1. Arduino UNO
2. Jumper Wires
3. 16×2 LCD Screen
4. Thermistor
5. 100 k ohm resistor
6. 10k potentiometer
7. Arduino IDE on computer

Reference Material:

1. In this project there is some stuff you need to know before getting started.
1. So a thermistor is a resistor whose resistance varies with temperature. You can learn more here (LINK).
2. We connect a known resistance in series with the thermistor and form a voltage divider and read off the voltage across the thermistor.
3. Then we convert the voltage to resistance.

Vout= voltage obtained from voltage divider
Vin= 5volts
R1= 100k ohms
Now calculate R2

1. To convert resistance to temperature, we have to make use of the Steinhart- Hart equation.

Code:

``````#include<LiquidCrystal.h>
int rs= 7;
int en=8;
int d4=12;
int d5=11;
int d6=10;
int d7=9;
LiquidCrystal lcd (rs, en, d4,d5,d6,d7);

int Thermistorpin=A0;
int Vo;
float R1=100000;
float logR2, R2, T;
float A=1.009249522e-03, B= 2.3784054444e-04, C=2.019202697e-07;

void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
pinMode(Thermistorpin, INPUT);
lcd.begin(16,2);

}

void loop() {
// put your main code here, to run repeatedly:
R2= R1*(1023.0/(float)Vo -1.0);
logR2= log(R2);
T=(1.0/(A+B*logR2 + C*logR2*logR2*logR2));
T=T-273.15;
//T= (T*9.0)/5.0 + 32.0;

Serial.print("Temperature: ");
Serial.print(T);
Serial.println(" C");

lcd.setCursor(0,0);
lcd.print("Tempertaure: ");
lcd.setCursor(0,1);
lcd.print(T);
lcd.print(" C");

delay(500);

}
``````

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Happy Learning!!

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