## Introduction: Arduino LED Temperature Indicator

Difficulty:easy..Basic breadboard and programming skills

View this project on my website to see a cool simulation of the circuit!

This design is made to keep track of the temperature in a room.

You give it the parameters you want and it will light a blue LED if it is too cold, a red LED if it's too hot, and a green one if it's just right.

You will need:

## Step 2: Make the Circuit

Wire it up:

• Red LED goes to digital pin 4 through one of the resistors and ground
• Green LED goes to digital pin 3 though a resistor and ground
• Blue LED goes to digital pin 2 through a resistor and ground
• Pin one (the pin on the left) of the temperature sensor goes to 5v
• Pin two (the pin in the middle) of the temperature sensor goes to analog pin A2
• Pin three (the pin on the right) of the temperature sensor goes to ground

-See the parts needed

## Step 3: Coding

Connect your Arduino to your computer and upload this code:

```const int hot = 87; //set hot parameter
const int cold = 75; //set cold parameter
void setup() {
pinMode(A2, INPUT); //sensor
pinMode(2, OUTPUT); //blue
pinMode(3, OUTPUT); //green
pinMode(4, OUTPUT); //red
Serial.begin(9600);
}
void loop() {
int sensor = analogRead(A2);
float voltage = (sensor / 1024.0) * 5.0;
float tempC = (voltage - .5) * 100;
float tempF = (tempC * 1.8) + 32;
Serial.print("temp: ");
Serial.print(tempF);
if (tempF < cold) { //cold
digitalWrite(2, HIGH);
digitalWrite(3, LOW);
digitalWrite(4, LOW);
Serial.println(" It's Cold.");
}
else if (tempF >= hot) { //hot
digitalWrite(2, LOW);
digitalWrite(3, LOW);
digitalWrite(4, HIGH);
Serial.println(" It's Hot.");
}
else { //fine
digitalWrite(2, LOW);
digitalWrite(3, HIGH);
digitalWrite(4, LOW);
Serial.println(" It's Fine.");
}
delay(10);
}

```

Open the Serial Monitor in the Arduino program, and watch what happens! You can also visit my website to see a simulation with a built-in serial monitor.

Participated in the
Home Hacks Challenge

Participated in the
Robotics Contest 2016