Digital Barometer and Altimeter Using BMP280 Sensor

A digital barometer is an instrument that measures air pressure electronically, and a digital altimeter is an instrument that reports height above a reference level; this project combines both instruments into one bench unit built around a BMP280 sensor, an Arduino Nano and a 0.96-inch OLED display. The sensor measures absolute air pressure, the Nano compensates the reading for temperature and converts it into altitude with the barometric formula, and the display shows pressure, altitude and temperature together, so a student can watch pressure fall as the unit is carried upstairs and altitude rise with it. The unit needs no phone app, cloud account or internet connection, and every reading is produced on the bench in front of the reviewer.

This is a built-to-order hardware project: the working prototype, firmware, wiring documentation and the complete viva kit (report, PPT, Q&A) are prepared fresh for you.

The Problem
The Digital Barometer and Altimeter Using BMP280 Sensor exists because ordinary weather apps and phone sensors hide the measurement students are supposed to learn. A student who reads pressure off a phone screen never sees a sensor flex under air pressure, never applies temperature compensation, and never converts a pressure reading into height, so the physics stays a formula on a slide. This project closes that gap with a bench unit the student builds and calibrates: a BMP280 sensor measures absolute air pressure, an Arduino Nano compensates the raw reading with the sensor's factory calibration data, converts it to altitude against a set sea-level pressure, and shows pressure, altitude and temperature on a small OLED display. Because the unit is carried between rooms, floors and outdoor spots, its readings change in front of the student, turning barometric theory into something demonstrable at a review.

Builder note from the actual build: pressure bends the diaphragm, and the diaphragm's resistance change is the measurement — everything else in this project is arithmetic. That is why the build keeps the BMP280 exposed to still room air, clear of warm components such as the Nano's voltage regulator, and away from draughts: a sensor that reads its neighbour's warmth instead of the room's air reports a convincing-looking number for the wrong quantity. The same note drives the calibration step in the delivery: sea-level pressure is entered for the place the unit will be demonstrated, and re-entered whenever the unit moves to a different town, because altitude computed against a stale reference is a precise answer to the wrong question.

The barometer and altimeter works as a short chain from air to display. The BMP280's piezoresistive sensing element flexes under air pressure, and that flex changes an electrical signal the sensor's internal circuitry converts into raw pressure and temperature values. The Arduino Nano reads those raw values over I2C, applies the temperature-compensation calculation using calibration coefficients stored in the sensor at the factory, and produces a compensated pressure in hectopascals. That pressure is then fed into the barometric formula together with a set sea-level pressure to give altitude in metres, while the trend logic compares the current pressure with an earlier stored reading. Finally the Nano writes pressure, altitude and temperature to the OLED screen and to the serial monitor, refreshing the display on a regular cycle. No internet connection is needed at any stage.

1. Air pressure acts on the BMP280's piezoresistive sensing element, which produces raw pressure and temperature signals.
2. The Arduino Nano reads the raw values over the I2C bus and applies the factory temperature-compensation calculation to produce compensated pressure in hectopascals.
3. The firmware converts compensated pressure into altitude in metres with the standard barometric formula, using the sea-level pressure value set in the firmware.
4. The trend logic compares the current pressure with the earlier stored reading and classifies the trend as rising, falling or steady.
5. The Nano updates the session minimum and maximum pressure and checks the push-button for a screen change or a relative-altitude zero.
6. Pressure, altitude and temperature are written to the 0.96-inch OLED display, and the same values are printed to the serial monitor for demonstration.

Tech stack:

• Arduino Nano (ATmega328P) · firmware in Arduino IDE
• Bosch BMP280 · piezoresistive barometric pressure sensor
• SSD1306 OLED display · 0.96-inch · 128 × 64 pixels · I2C
• I2C bus · shared sensor and display communication
• Adafruit BMP280 and SSD1306 libraries · sensor and display drivers
• USB 5 V supply · bench power for the prototype

The barometer and altimeter unit is built around four capabilities that work together: live pressure, altitude and temperature on one OLED screen, barometric altitude calculated from compensated pressure against a set sea-level pressure, a pressure-trend indicator that shows whether pressure is rising, falling or steady, and a relative-altitude mode that zeroes height at the student's current position for floor-to-floor or hill-climb demonstrations. Around those four, the firmware applies the BMP280's factory temperature compensation to every reading, keeps a running minimum and maximum pressure for the session, and prints the same readings to the serial monitor for viva demonstration. Every capability is visible on the bench unit itself, with no phone app, cloud account or internet connection in the loop. A single push-button cycles the display screens, and a long press re-zeroes relative altitude, so the whole instrument is operated without a computer once it is powered.

• [Live pressure, altitude and temperature display] The OLED screen shows compensated pressure in hectopascals, altitude in metres and temperature in degrees Celsius on one screen, refreshed on a regular cycle, so all three quantities can be read at a glance during a demonstration.
• [Barometric altitude from compensated pressure] Altitude is calculated from compensated pressure with the standard barometric formula against a sea-level pressure value set in the firmware, so the student can explain exactly how a pressure sensor becomes an altimeter.
• [Pressure-trend indicator] The firmware compares the current pressure with an earlier stored reading and shows whether pressure is rising, falling or steady, giving the barometer its classic weather-watching use in miniature.
• [Relative-altitude mode] A long press on the push-button zeroes altitude at the unit's current position, so height gained climbing stairs or walking uphill reads directly from zero without any sea-level reference.
• [Factory temperature compensation] Every pressure reading is corrected with the calibration coefficients stored in the BMP280 at the factory, so the temperature reading and the pressure reading stay consistent as the room warms or cools.
• [Session minimum and maximum pressure] The firmware tracks the lowest and highest pressure seen since power-on and shows them on a second display screen, giving the reviewer a simple record of the session's pressure range.
• [Serial monitor output for demonstration] The same pressure, altitude and temperature values are printed to the serial monitor, so the readings can be shown on a laptop screen or captured during a review alongside the OLED display.

Implemented in the base project, configurable, and future scope, kept separate: the base project implements all seven features above on the bench unit. Sea-level pressure, display refresh interval and the trend comparison interval are configurable in the firmware. Data logging to a memory card, wireless transmission of readings, a larger display and a weather-forecast screen are optional customisations or future scope only, and are not part of the base project.

• Working bench prototype: Arduino Nano, BMP280 sensor module, 0.96-inch OLED display, push-button and breadboard wiring
• Complete firmware source code with temperature compensation, barometric altitude, trend indicator, relative-altitude mode and serial output
• Circuit and wiring documentation showing the I2C connections for the sensor and the display
• Component list with the sensor, controller and display used
• Setup and calibration instructions, including how to set sea-level pressure and re-zero relative altitude
• Project report PDF covering background, piezoresistive sensing, compensation, the barometric formula, implementation and limitations
• PPT presentation for the final review
• Viva Q&A preparation document covering barometric pressure, temperature compensation, I2C, altitude derivation and the sensor's accuracy limits

Build timeline and support: the build runs in four stages in order — prototype assembly and wiring, firmware with compensation and altitude calculation, bench calibration against a known sea-level pressure, then documentation and the viva kit — and support covers setup guidance, a demonstration walkthrough and help explaining the readings at review.

To request a quotation, message Projectech on WhatsApp with the project name, the scope you want (the base barometer and altimeter unit, or the base unit plus data logging as a customisation), and your delivery date; Projectech replies with a quotation covering scope, price, and delivery timeline.