Electronic altimeter using PIC16F877

This circuit was designed by Matthias Stehr. The design uses a PIC16F877 to measure the output of a temperature sensor and an absolute pressure transducer to measure altitude. Specifically, the design provides the following features:

displays the current air-pressure
displays the current temperature
calibration
saving and displaying the reference pressure
calculating and displaying of the relative altitude (resolution 7m)
saving of the altitude data in a 2k EE-Prom in a interval from 1s-60s (result in a recording time from 17min - max. 17h)
can be powered by a 9V battery (about 24h) or a 12V DC power supply unit
operation with 3 keys and LCD menu
saved data can be transferred to a PC with illustration and transfer handled by a C++ program
data can be saved in a simple text file