Note: This library is not maintained and is here for archival only.
Had some trouble getting an 74HC595 3 digit display to work. So I used the Fast library (https://github.com/GitMoDu/Fast) to bitbang it from scratch, with some nice abstractions to simply write numbers.
Tested in: ATmega328p, ATTiny85.
Example indicators for speed and RPM (https://github.com/GitMoDu/RPMWS2812).
