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Arduino library which defines
methods for accessing the 3-Color LED Rotary Encoder. This is manufactured by Top-Up and other companies and is available from many
sources on the internet. The manufacturer's serial number is EC12PSD-017 and it can be found referenced at sources such as
https://www.sparkfun.com/products/10982 or https://www.proto-pic.co.uk/rotary-encoder-illuminated-rgb.html along with numerous other
places on eBay or Amazon. The encoder sends out rotational information on 2 pins using a quadrature system and also has a pushbutton. The Bourns PEL2T is an identical model and this library and sample code will work for this rotary encoder as well.
While I've seen a couple of libraries that will work for this encoder, I wanted to use this in a project and opted to create a specific library for it. It not only supports setting colors for the clockwise, counterclockwise and pushbutton along with a pleasing fade; but is also designed to work with Atmel's/Arduino's interrupts so that any program using this class can process normally and only query the pushbutton state and the current rotational value when it needs to. Using interrupts limits the class to those pins which support hardware interrupt, but that limitation is offset by the efficiency with which the class works.
The hardware interrupt pins vary from one Atmel processor to another and need to be checked; the example programs for this class use those pins available for the Arduino Micro (ATmega32U4). Newer processors impose less restrictions on which hardware interrupts can be used. Likewise the 3 pins used for the Red, Green and Blue LED lights need to be PWM-capable pins, which vary from processor to processor. The rotary encoder uses a common cathode (+) pin, so the 3 lights are driven to ground for full power and high for "OFF"; meaning an analog write of "255" turns the respective LED off and an analog write of "0" turns it on at full power.
Fading of the LEDs is done by using the same timer that millis() uses, timer0, and triggering a fade pulse every millisecond.
See the example program for the breadboard wiring using an Arduino Micro with pin connections as used in these wiki pages.
