This was originally a project to build a simple altimeter to record the apogee of mid power rocket flights... Then things got out of hand as they are liable to do in this hobby........
The complex version runs on an ESP8266 (or compatible) and includes sensor fusion to calculate spatial orientation, pyro and servo channels, a web server and an oled display to provide a "nice" user interface.
The "simple" version is designed for an Arduino nano and has no interface beyond the serial logger and the indicator LEDs.
To build this, you'll need an Arduino - a nano is best or an ESP8266. An ESP12 should also work but hasn't been tested.
The pinouts are noted in Configuration.h. There are several LEDs for indicators, a pin for an active peizo and two pins which can be used for firing ematches via an NPN mosfet. Two pins are also allocated to control servos for parachute deployment (and/or for active flight control for the ambitious).
The complex version also includes support for Oled displays via i2c. A second switch can be used to navigate between the screens.
Notes:
- Power can be supplied from a 2s lipo. Both the arduino nano and ESP8266 based boards like the Node MCU v1.0 will happily run off of an ~7.4V supply. If using a nano with only a barometer, you can also use a pair of lithium button cells to construct a unit not much larger than a a commercial altimeter.
- For deployment, it is advised to add a ~1A 5V regulator to drive the servos and/or mosfets. You can get away with powering a small piezo and the indicator LEDs directly from the logic pin but be cautious. Use a transistor switch for anything that exceeds the single pin current rating for whichever micro controller you choose. You may be able to drive a small servo from the arduino 5V Vout as well. This will not work for any board with 3.3V logic.
...Happy Flying