How to Use Adafruit MPL3115A2 I2C Barometric Pressure, Altitude, Temperature Sensor: Examples, Pinouts, and Specs

The Adafruit MPL3115A2 is a compact, high-precision sensor module capable of measuring barometric pressure, altitude, and temperature. Utilizing the I2C communication protocol, it interfaces seamlessly with a wide range of microcontrollers, including the popular Arduino platform. This sensor is ideal for a variety of applications, such as personal weather stations, GPS navigation systems, drones, and altimeters.

• Pressure Range: 20 to 110 kPa
• Altitude Range: -700 to 10,000 m
• Temperature Range: -40 to 85°C
• Resolution: 0.01 kPa (pressure), 0.1 m (altitude), 0.1°C (temperature)
• Operating Voltage: 2.5V to 5.5V
• Interface: I2C (up to 400 kHz)
• 2.5 µA low power standby mode

1. Connecting the Sensor:

   • Connect VDD to the 3.3V output on the Arduino.
   • Connect GND to a ground pin on the Arduino.
   • Connect SCL to the A5 pin (SCL) on the Arduino UNO.
   • Connect SDA to the A4 pin (SDA) on the Arduino UNO.
   • The INT pin can be left unconnected if the interrupt feature is not used.

2. Library Installation:

   • Install the Adafruit MPL3115A2 library using the Arduino Library Manager or download it from the Adafruit GitHub repository.

3. Initialization and Configuration:

   • Include the Adafruit MPL3115A2 library in your sketch.
   • Create an instance of the sensor and begin communication.

4. Reading Sensor Data:

   • Use the provided functions in the library to read pressure, altitude, and temperature.

#include <Wire.h>
#include <Adafruit_MPL3115A2.h>

// Create an MPL3115A2 instance
Adafruit_MPL3115A2 baro = Adafruit_MPL3115A2();

void setup() {
  Serial.begin(9600);
  if (!baro.begin()) {
    Serial.println("Could not find a valid MPL3115A2 sensor, check wiring!");
    while (1);
  }
}

void loop() {
  float pressure = baro.getPressure(); // Get pressure in Pascals
  float altitude = baro.getAltitude(); // Get altitude in meters
  float temperature = baro.getTemperature(); // Get temperature in Celsius

  // Print the sensor readings
  Serial.print("Pressure: ");
  Serial.print(pressure);
  Serial.println(" Pa");
  Serial.print("Altitude: ");
  Serial.print(altitude);
  Serial.println(" m");
  Serial.print("Temperature: ");
  Serial.print(temperature);
  Serial.println(" C");

  delay(500); // Wait half a second between readings
}

• Ensure that the sensor is not exposed to condensation or water as it is not waterproof.
• Avoid physical stress and excessive heat to prevent damage to the sensor.
• Use pull-up resistors on the I2C lines if multiple devices are connected to the bus.
• For accurate altitude measurements, calibrate the sensor to a known pressure or altitude before use.

• Sensor Not Detected: Ensure that the wiring is correct and that the sensor is properly powered.
• Inaccurate Readings: Calibrate the sensor, check for sources of heat near the sensor, and ensure that the sensor is not in a rapidly changing environment.
• I2C Communication Errors: Check for loose connections and ensure that pull-up resistors are in place if necessary.

Q: Can the MPL3115A2 be used with a 5V microcontroller? A: Yes, the sensor can be interfaced with a 5V microcontroller, but ensure that the I2C lines are level-shifted to be compatible with the sensor's voltage levels.

Q: How can I calibrate the sensor for altitude measurements? A: Use the setSeaPressure() function in the library to calibrate the sensor to the current sea level pressure.

Q: What is the purpose of the INT pin? A: The INT pin can be used to trigger an interrupt on the microcontroller when a measurement is ready or when certain pressure/altitude thresholds are reached.

For further assistance, consult the Adafruit MPL3115A2 datasheet and the Adafruit support forums.