[JamesBrown]

For encoder 1 phase A goes to dig_in 1 phase b to dig_in 11
encoder 2 uses 2 and 12, 3 uses 3 and 13, ans so on.

There is not more than one option, the encoder or gear tooth sensor just pulses once for every set fraction of a rotation, ie when ever the gear tooth sensor senses a gear tooth. This pulse triggers an interrupt in Kevin's code and that tallies the number of pulses, adding one for each forward pulse and subtracting one for each reverse pulse. This tally is returned by get_encoder_count.