“This is the building description of an Altimeter (Altitude Meter) based on an Arduino Nano and a Bosch BMP180 atmospheric pressure sensor.
The design is simple but the measurements are stable and quite accurate (1m precision).
Every second ten pressure samples are made and the average of these ten is calculated. This pressure is compared to a baseline pressure and is used to process the altitude. The baseline pressure is measured at the moment the altimeter is powered on so this represents an altitude of zero meter. If necessary the baseline pressure can be reset by pushing the button.
During setting the baseline (power on or button push) the current atmospheric pressure is displayed for one second. After this the altitude is on the 4-digit display and this will update about every second.
A red led is used for negative altitudes when going down-hill after setting the baseline.
The altimeter is powered by an USB cable so can be used in a car, motorcycle or on every other place with USB or a power bank.
Two special libraries are used. One for the BMP180 that can be found here. And one for the TM1637 4-digit display that can be found here.
The BMP180 is not the newest version. It seems to bereplaced by the BMP280. It should be simple to replace the BMP180 with the BMP280 in this design.
Parts of the sketch are based on the BMP180_altitude_example.ino delivered with the BMP180 library.”