How to Use MPL31115A2: Examples, Pinouts, and Specs

The MPL3115A2 is a digital barometer and altimeter sensor manufactured by SparkFun, designed to provide highly accurate pressure and altitude measurements. This sensor communicates via the I2C interface, making it easy to integrate into a wide range of projects. It is ideal for applications such as weather monitoring, altitude tracking, and GPS enhancement.

• Weather stations for atmospheric pressure monitoring
• Altitude tracking in drones and model aircraft
• GPS systems for elevation correction
• Wearable devices for fitness and outdoor activities
• Environmental data logging systems

The following table outlines the key technical details of the MPL3115A2 sensor:

The MPL3115A2 sensor has the following pinout:

1. Power the Sensor: Connect the VIN pin to a 3.3V power source and the GND pin to ground.
2. I2C Communication: Connect the SDA and SCL pins to the corresponding I2C pins on your microcontroller (e.g., Arduino UNO: A4 for SDA, A5 for SCL).
3. Optional Interrupt: If you want to use the interrupt feature, connect the INT pin to a digital input pin on your microcontroller.
4. Pull-Up Resistors: Ensure that the I2C lines (SDA and SCL) have pull-up resistors (typically 4.7kΩ) if not already provided on your board.

• Use a stable 3.3V power supply to ensure accurate readings.
• Avoid placing the sensor in areas with high electromagnetic interference.
• Calibrate the sensor for your specific altitude and pressure conditions for optimal accuracy.
• Use proper decoupling capacitors (e.g., 0.1 µF) near the power pins to reduce noise.

Below is an example Arduino sketch to read altitude and pressure data from the MPL3115A2:

#include <Wire.h>
#include <SparkFunMPL3115A2.h> // Include the SparkFun MPL3115A2 library

MPL3115A2 mySensor; // Create an instance of the sensor

void setup() {
  Serial.begin(9600); // Initialize serial communication
  Wire.begin();       // Initialize I2C communication

  // Initialize the MPL3115A2 sensor
  if (!mySensor.begin()) {
    Serial.println("MPL3115A2 not detected. Check connections.");
    while (1); // Halt execution if the sensor is not found
  }

  // Set the sensor to Altimeter mode
  mySensor.setModeAltimeter();
  Serial.println("MPL3115A2 initialized in Altimeter mode.");
}

void loop() {
  // Read altitude in meters
  float altitude = mySensor.readAltitude();
  Serial.print("Altitude (m): ");
  Serial.println(altitude);

  // Read pressure in Pascals
  float pressure = mySensor.readPressure();
  Serial.print("Pressure (Pa): ");
  Serial.println(pressure);

  // Read temperature in Celsius
  float temperature = mySensor.readTemp();
  Serial.print("Temperature (°C): ");
  Serial.println(temperature);

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

• Install the SparkFun MPL3115A2 library via the Arduino Library Manager before running the code.
• Ensure the I2C address (default: 0x60) matches the sensor's configuration.

1. Sensor Not Detected

   • Cause: Incorrect wiring or I2C address mismatch.
   • Solution: Verify the connections and ensure the SDA and SCL lines are properly connected. Check the I2C address in the code.

2. Inaccurate Readings

   • Cause: Lack of calibration or unstable power supply.
   • Solution: Calibrate the sensor for your environment and use a stable 3.3V power source.

3. No Data Output

   • Cause: Library not installed or incorrect initialization.
   • Solution: Ensure the SparkFun MPL3115A2 library is installed and the begin() function is called in the setup.

Q: Can the MPL3115A2 measure temperature?
A: Yes, the sensor includes a built-in temperature sensor with a resolution of 0.1°C.

Q: What is the maximum altitude the sensor can measure?
A: The MPL3115A2 can measure altitudes up to 10,000 meters above sea level.

Q: Can I use the MPL3115A2 with a 5V microcontroller?
A: Yes, but you must use a logic level shifter to safely interface the 3.3V I2C lines with the 5V microcontroller.

Q: Does the sensor require calibration?
A: While the sensor is factory-calibrated, additional calibration may improve accuracy in specific environments.

Q: How do I switch between Altimeter and Barometer modes?
A: Use the setModeAltimeter() and setModeBarometer() functions provided by the SparkFun library.