Variometer (cockpit instrument)

Variometer with mechanical needle and LCD for use with [Openvario](http://www.openvario.org/). Can also be used for simulators. Work in progress.

This is a standard 60x60mm instrument (57mm diameter hole). Its designed around the [x27.168](https://www.adafruit.com/product/2424) automotive gauge stepper motor, a rotary encoder (Keyes 040 for now) and one of these two displays:
- [1.3" SHARP Memory LCD](https://learn.adafruit.com/adafruit-sharp-memory-display-breakout).
- [1.54" Waveshare E-ink display](https://www.waveshare.com/wiki/1.54inch_e-Paper_Module)

Both displays are are perfectly sunlight readable, but have no backlight. Cockpit sim builders may want to use an OLED instead, and will have to modify the design.

The eink displays looks a little better, is larger and has a higher resolution; but the update rate is slow, on the order of 2 frames per second.

This 5V stepper can be driven directly from an arduino, but for smoother movement, I recommend you use a micr