Rotary Encoder Interface

[Kevin Townsend]

The nRF51 and nRF52 both have a HW quadrature decoder, making it easy to 
use rotary encoders like https://www.adafruit.com/product/377) without 
all kinds of GPIO processing.

Rotary encoders with a select switch are a really nice feedback 
mechanism and you can design a fairly rich physical UX with just one of 
them.

We have the sensor API, but where would a driver for something like this 
fit into Mynewt, in your opinion(s)?

There are other similar options like cap touch (I guess that could be a 
sensor?), numeric keypad entry (https://www.adafruit.com/product/419), 
or a GPIO grid for keyboard input.

I'm willing to submit a driver for the encoder, but there should 
probably be some discussion of the lower level framework for this kind 
of input device???

Kevin