In this project we will get the current altitude and temperature using an MPL3115A2 pressure sensor connected to an LCD keypad shield fitted to an Arduino Uno

Here is a little information regarding the sensor.

The MPL3115A2 is a compact, piezoresistive, absolute pressure sensor with an I2C digital interface. MPL3115A2 has a wide operating range of 20 kPa to 110 kPa, a range that covers all surface elevations on earth. The MEMS is temperature compensated utilizing an on-chip temperature sensor. The pressure and temperature data is fed into a high resolution ADC to provide fully compensated and digitized outputs for pressure in Pascals and temperature in °C.

The compensated pressure output can then be converted to altitude, utilizing the formula stated in Section 9.1.3 “Pressure/altitude” provided in meters.The internal processing in MPL3115A2 removes compensation and unit conversion load from the system MCU, simplifying system design

Parts List

I used the following parts for this project

Schematics/Layout

lcd shield and MPL3115A2 layout

Code

We need to add a library via the library manager or download it from – https://github.com/adafruit/Adafruit_MPL3115A2_Library

Source code

#include <Wire.h>
#include <LiquidCrystal.h>
#include <Adafruit_MPL3115A2.h>
 
//setup for the LCD keypad shield
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
Adafruit_MPL3115A2 baro = Adafruit_MPL3115A2();
 
void setup() 
{
  //init serial for some debug
  Serial.begin(9600);
  Serial.println("Adafruit_MPL3115A2 test!");
 
  //init LCD
  lcd.begin(16,2);
  //line 1 - temperature
  lcd.setCursor(0,0);
  lcd.print("ALTITUDE");
  //line 2 - humidity
  lcd.setCursor(0,1);
  lcd.print("TEMPERATURE");
}
 
void loop() 
{
  if (! baro.begin()) 
  {
    Serial.println("Couldnt find sensor");
    return;
  }
  float pascals = baro.getPressure();
  float altm = baro.getAltitude();
  float tempC = baro.getTemperature();
  //display readings on lcd  
  lcd.setCursor(0,0);
  lcd.print("Alt = ");
  lcd.print(altm);
  lcd.print(" m");
  lcd.setCursor(0,1);
  lcd.print("Temp = ");
  lcd.print(tempC);
  lcd.print(" *c");
 
  delay(500);
}

Output

Here is a video showing my results, you should get similar results on your LCD

Links

https://www.nxp.com/docs/en/data-sheet/MPL3115A2.pdf