BMP180 Barometric Pressure and Altitude Sensor Module, I2C

Air pressure drops predictably with altitude, and the BMP180 takes advantage of that physical relationship to let a project estimate its own height above sea level purely from a pressure reading - no GPS or external reference needed, just the sensor's own measurement of the surrounding air pressure converted through a known physics formula into an altitude estimate.

Pressure measurement range spans 300 to 1100 hectopascals, corresponding to roughly 9000 meters up to 500 meters below sea level, a genuinely wide range covering everything from high-altitude flight down to below-sea-level applications. Resolution reaches an impressive 0.03hPa, translating to altitude resolution as fine as 0.25 meters - precise enough to detect genuinely small altitude changes, which matters considerably for applications like drone altitude-hold where even small height drift needs to be caught and corrected.

Communication runs over a simple I2C interface at a fixed 7-bit address (0x77), with an onboard 3.3V regulator and I2C level shifter plus pull-up resistors already included on the board - meaning the module can be wired directly to either 3.3V or 5V logic microcontroller systems without needing external level-shifting circuitry. Firmware behavior is identical to the earlier BMP085 chip, so existing BMP085 code and libraries generally work without modification.

An onboard temperature sensor is also included, both supporting the pressure-to-altitude calculation (temperature affects air density and therefore the pressure-altitude relationship) and providing a standalone temperature reading in its own right, accurate to within 2C. Builders working on a drone or RC aircraft needing altitude-hold capability, a weather-monitoring station, or any project needing reasonably precise altitude estimation from ambient pressure will find the BMP180 a well-proven, extensively documented sensor for that specific measurement task.