Temperature-Based LED Indicator with Arduino

Project Overview:

This project uses an Arduino to read temperature values and control a series of LEDs based on the temperature. The LEDs light up sequentially as the temperature increases, providing a visual indication of the temperature range.

How It Works:

A temperature sensor (e.g., LM35) is connected to the Arduino, which reads the temperature as an analog value. The Arduino then maps this value to a temperature in Celsius. Depending on the temperature, different combinations of LEDs are turned on to indicate the current temperature range.

Components List:

1. Arduino Board (e.g., Uno, Nano, etc.)
2. Temperature Sensor (e.g., LM35)
3. 4 LEDs
4. 220-ohm Resistors (for each LED)
5. Jumper Wires
6. Breadboard (optional)
7. Power Supply (for Arduino)

Software List:

• Arduino IDE (Integrated Development Environment)

Circuit Diagram and Connection:

Component	Arduino Pin
Temperature Sensor (Vout)	A0
LED1	Digital Pin 2
LED2	Digital Pin 3
LED3	Digital Pin 4
LED4	Digital Pin 5
Resistors (220-ohm)	Between each LED and GND

1. Connect the temperature sensor's output pin to Analog Pin A0 on the Arduino.

2. Connect the anode (long leg) of each LED to Digital Pins 2 through 5 on the Arduino, and the cathode (short leg) to GND through a 220-ohm resistor.

Project Code:

int baselineTemp = 30;

int celsius;

void setup() {

  pinMode(A0, INPUT);

  Serial.begin(9600);

  pinMode(2, OUTPUT);

  pinMode(3, OUTPUT);

  pinMode(4, OUTPUT);

  pinMode(5, OUTPUT);

}

void loop() {

  // Read and map the analog value from the temperature sensor to Celsius

  celsius = map(((analogRead(A0) - 20) * 3.04), 0, 1023, -40, 125);

  // Control LEDs based on the temperature range

  if (celsius < baselineTemp) {

    digitalWrite(2, LOW);

    digitalWrite(3, LOW);

    digitalWrite(4, LOW);

    digitalWrite(5, LOW);

  } else if (celsius >= baselineTemp && celsius < baselineTemp + 10) {

    digitalWrite(2, HIGH);

    digitalWrite(3, LOW);

    digitalWrite(4, LOW);

    digitalWrite(5, LOW);

  } else if (celsius >= baselineTemp + 20 && celsius < baselineTemp + 30) {

    digitalWrite(2, HIGH);

    digitalWrite(3, HIGH);

    digitalWrite(4, LOW);

    digitalWrite(5, LOW);

  } else if (celsius >= baselineTemp + 30 && celsius < baselineTemp + 40) {

    digitalWrite(2, HIGH);

    digitalWrite(3, HIGH);

    digitalWrite(4, HIGH);

    digitalWrite(5, LOW);

  } else if (celsius >= baselineTemp + 60) {

    digitalWrite(2, HIGH);

    digitalWrite(3, HIGH);

    digitalWrite(4, HIGH);

    digitalWrite(5, HIGH);

  }

  delay(1000);  // Wait for 1 second before the next reading

}

Explanation of the Code:

• Variable Declaration:

• int baselineTemp = 30; sets a baseline temperature of 30°C.

• int celsius; is used to store the calculated temperature in Celsius.

• Setup Function:

• pinMode(A0, INPUT); sets the analog pin connected to the temperature sensor as an input.

• pinMode(2, OUTPUT); through pinMode(5, OUTPUT); sets the LED pins as outputs.

• Loop Function:

• celsius = map(((analogRead(A0) - 20) * 3.04), 0, 1023, -40, 125); reads the analog value from the temperature sensor and maps it to a temperature in Celsius.

• The if statements control the LEDs based on the temperature range.

Test and Troubleshooting:

1. Testing: Upload the code to your Arduino. Adjust the temperature sensor (e.g., using a heat source) and observe the LEDs lighting up based on the temperature range.

2. Troubleshooting:

• Ensure the temperature sensor is correctly connected to Analog Pin A0.

• Verify that each LED is functioning properly by testing them individually.

Summary:

This project uses an Arduino and a temperature sensor to create a simple temperature indicator with LEDs. The project demonstrates basic analog reading, mapping values, and controlling LEDs based on conditional logic.