Sensor data scaling is a crucial aspect of working with sensors in embedded systems, including those using Arduino. Sensors often output data in a range that doesn't directly correspond to the desired range for your application. For instance, a temperature sensor might output a voltage between 0V and 5V, but you need to convert this to a temperature range of -40°C to 125°C. Scaling this data correctly ensures that your system interprets sensor readings accurately, allowing for proper decision-making and control.

In this article, we will explore how to scale sensor data using Arduino. We will cover the importance of data scaling, how to implement it in an Arduino environment, and provide a practical example using a temperature sensor.

Project: Our project will involve reading data from an LM35 temperature sensor and scaling the output voltage to a temperature range in Celsius. The objectives are:

• Read the analog voltage from the LM35 sensor.
• Scale the voltage to a temperature range.
• Display the temperature on the Serial Monitor.

Components List:

• Arduino Uno (1)
• LM35 Temperature Sensor (1)
• Breadboard (1)
• Jumper Wires (as needed)

Examples:

// Define the analog pin connected to the LM35 sensor
const int sensorPin = A0;

// Variable to store the raw sensor value
int sensorValue = 0;

// Variable to store the scaled temperature value
float temperatureC = 0;

void setup() {
  // Initialize the Serial Monitor
  Serial.begin(9600);
}

void loop() {
  // Read the raw analog value from the sensor
  sensorValue = analogRead(sensorPin);

  // Convert the analog value to voltage
  // The Arduino ADC provides a value between 0 and 1023
  // Corresponding to a voltage range of 0V to 5V
  float voltage = sensorValue * (5.0 / 1023.0);

  // Convert the voltage to temperature in Celsius
  // According to the LM35 datasheet, 10mV = 1°C
  temperatureC = voltage * 100;

  // Print the temperature to the Serial Monitor
  Serial.print("Temperature: ");
  Serial.print(temperatureC);
  Serial.println(" °C");

  // Wait for a second before taking another reading
  delay(1000);
}

Explanation:

• We start by defining the analog pin connected to the LM35 sensor.
• In the setup() function, we initialize the Serial Monitor to display the temperature readings.
• In the loop() function, we read the raw analog value from the sensor using analogRead().
• We then convert this raw value to a voltage by multiplying by the factor (5.0 / 1023.0), since the Arduino ADC converts the input voltage (0-5V) to a number between 0 and 1023.
• The voltage is then converted to temperature in Celsius using the formula voltage * 100, as per the LM35 datasheet (10mV = 1°C).
• Finally, we print the temperature to the Serial Monitor and wait for a second before taking the next reading.