How to Use MPL115A1 / MPL115A2 Barometer (Family Diagram): Examples, Pinouts, and Specs

The MPL115A1 and MPL115A2 are digital barometric pressure sensors designed to provide accurate atmospheric pressure readings with built-in temperature compensation. These sensors are compact, low-power, and ideal for applications requiring precise pressure measurements. They communicate via an I²C or SPI interface, making them easy to integrate into microcontroller-based systems.

• Weather stations
• Altimeters for drones and aircraft
• HVAC systems
• Portable weather monitoring devices
• Environmental data logging

1. Power Supply: Connect the VDD pin to a 3.3V or 5V power source and the GND pin to ground.
2. Communication Interface:
   • For I²C: Connect the SCL and SDA pins to the corresponding I²C pins on your microcontroller. Use pull-up resistors (typically 4.7 kΩ) on both lines.
   • For SPI (MPL115A1 only): Connect the CSB, SCLK, SDI, and SDO pins to the corresponding SPI pins on your microcontroller.
3. Bypass Capacitor: Place a 0.1 µF capacitor close to the VDD pin for power supply decoupling.
4. Initialization: Configure the microcontroller to communicate with the sensor using the chosen interface.

• Ensure the operating voltage matches the sensor's specifications.
• Use proper pull-up resistors for I²C communication.
• Avoid placing the sensor near heat sources to prevent inaccurate readings.
• Calibrate the sensor if required for your application.

#include <Wire.h>

// MPL115A2 I2C address
#define MPL115A2_ADDRESS 0x60

// Register addresses
#define PRESSURE_MSB 0x00
#define PRESSURE_LSB 0x01
#define TEMPERATURE_MSB 0x02
#define TEMPERATURE_LSB 0x03
#define START_CONVERSION 0x12

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

void loop() {
  // Start pressure and temperature conversion
  Wire.beginTransmission(MPL115A2_ADDRESS);
  Wire.write(START_CONVERSION);
  Wire.endTransmission();
  delay(5); // Wait for conversion to complete

  // Read pressure and temperature data
  Wire.beginTransmission(MPL115A2_ADDRESS);
  Wire.write(PRESSURE_MSB);
  Wire.endTransmission();
  Wire.requestFrom(MPL115A2_ADDRESS, 4);

  if (Wire.available() == 4) {
    uint16_t pressure = (Wire.read() << 8) | Wire.read();
    uint16_t temperature = (Wire.read() << 8) | Wire.read();

    // Convert raw data to human-readable values
    float pressure_kPa = pressure / 64.0; // Example conversion
    float temperature_C = temperature / 64.0; // Example conversion

    // Print results
    Serial.print("Pressure (kPa): ");
    Serial.println(pressure_kPa);
    Serial.print("Temperature (°C): ");
    Serial.println(temperature_C);
  }

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

1. No Data from Sensor:

   • Ensure the sensor is powered correctly and the ground is connected.
   • Verify the I²C or SPI connections and check for loose wires.
   • Confirm the correct I²C address (default: 0x60) is being used.

2. Inaccurate Readings:

   • Check for nearby heat sources that may affect temperature compensation.
   • Ensure the sensor is not exposed to excessive moisture or contaminants.
   • Verify the calibration coefficients if using custom calculations.

3. Communication Errors:

   • Ensure pull-up resistors are present on the I²C lines.
   • Check the SPI clock speed and ensure it is within the sensor's specifications.

Q: Can the MPL115A1/MPL115A2 measure altitude?
A: Yes, by calculating the difference between the measured pressure and the standard sea-level pressure, you can estimate altitude.

Q: What is the difference between MPL115A1 and MPL115A2?
A: The MPL115A1 supports both I²C and SPI communication, while the MPL115A2 supports only I²C.

Q: Do I need to calibrate the sensor?
A: The sensor comes pre-calibrated, but you can perform additional calibration for higher accuracy in specific applications.

Q: Can I use this sensor with a 5V microcontroller?
A: Yes, the sensor supports operating voltages up to 5.5V, making it compatible with 5V systems like Arduino UNO.