Arduino Temperature

1. Designing the circuit

• Connect your temperature sensor (e.g., a thermistor or any analog temperature sensor) to analog pin A0.

• Connect four LEDs (with appropriate current-limiting resistors) to digital pins 10, 11, 12, and 13 for blue, green, orange, and red, respectively.

  • You can change the LEDs colour by clicking on it and change the colour

• The resistance value can be changed on the resistors by clicking them, set them to 220

• Upload the code to your Arduino board using the Arduino IDE.

• Open the Serial Monitor in the Arduino IDE to view the ADC value, temperature, and voltage readings.

• Observe how the LEDs change based on the temperature range.

• This code provides a simple temperature monitoring system with visual LED indicators. The LEDs will change their state according to the detected temperature.

2. Define Constants and Variables

• const int tempPin = A0: Specifies the analog pin (A0) where the temperature sensor is connected.

• const int redLED = 13, orangeLED = 12, greenLED = 11, blueLED = 10: Define the digital pins for four LEDs.

• int adcValue;, float voltage, temperature;: Variables to store the analog-to-digital converter (ADC) reading, voltage, and temperature values.

  Code

  const int tempPin = A0;
  const int redLED = 13, orangeLED = 12, greenLED = 11, blueLED = 10;
  int adcValue;
  float voltage, temperature;
  

3. Setup Function:

• Set the pinMode for tempPin as INPUT since it's used to read the analog sensor.

• Set the pinMode for redLED, orangeLED, greenLED, and blueLED as OUTPUT to control the LEDs.

• Initialize the serial communication at a baud rate of 9600 to enable data logging and debugging.

  Code

  void setup()
  {
    pinMode(tempPin,INPUT);
    
    pinMode(redLED,OUTPUT);
    pinMode(orangeLED,OUTPUT);
    pinMode(greenLED,OUTPUT);
    pinMode(blueLED,OUTPUT);
    
    Serial.begin(9600); // bits per second AKA Baud Rate
  }
  

4. Loop Function:

To code the loop function you need to do the following:

• Read the analog value from tempPin using analogRead and store it in adcValue.

• Calculate the temperature using a formula and store it in temperature.

• Calculate the voltage using the ADC value and store it in voltage.

• Call the tempIndicator function to control the LED indicators based on the temperature.

• Print the adcValue, temperature, and voltage to the serial monitor for monitoring.

• Add a short delay(500) of 500 milliseconds for smoother display updates.

  Code

  void loop()
  {
      adcValue = analogRead(tempPin);  // Read the analog value from tempPin.
      
      // Calculate temperature and voltage based on the ADC reading.
      temperature = ((adcValue * (5.0 / 1024 )) - 0.5) / 0.01;
      voltage = (5.0 / 1024) * adcValue;
      
      // Call the tempIndicator function to control LED indicators.
      tempIndicator(temperature);
    
      // Print ADC value, temperature, and voltage to the serial monitor.
      Serial.print("ADC: ");
      Serial.print(adcValue);
      Serial.print("  | Temp: ");
      Serial.print(temperature, 2);
      Serial.print("  |  Voltage: ");
      Serial.print(voltage, 3);
      Serial.println("V");
      
      delay(500);  // Add a short delay for smoother display updates.
  }
  

5. tempIndicator() Function:

The tempIndicator(temperature); placed in the loop() coded out above, functionality needs to be written. Outside the loop() functions final } create a new line and reproduce the following code:

void tempIndicator(float L_temp)
{
  // Control LEDs based on the temperature range.
  if (L_temp <= 5.0)
  {
    digitalWrite(redLED, LOW);
    digitalWrite(orangeLED, LOW);
    digitalWrite(greenLED, LOW);
    digitalWrite(blueLED, HIGH);
  }
  else if (L_temp > 5.0 && L_temp <= 20.0)
  {
    digitalWrite(redLED, LOW);
    digitalWrite(orangeLED, LOW);
    digitalWrite(greenLED, HIGH);
    digitalWrite(blueLED, LOW);
  }
  else if (L_temp > 20.0 && L_temp <= 30.0)
  {
    digitalWrite(redLED, LOW);
    digitalWrite(orangeLED, HIGH);
    digitalWrite(greenLED, LOW);
    digitalWrite(blueLED, LOW);
  }
  else if (L_temp > 30)
  {
    digitalWrite(redLED, HIGH);
    digitalWrite(orangeLED, LOW);
    digitalWrite(greenLED, LOW);
    digitalWrite(blueLED, LOW);
  }
}