NeoPixel Ring Clock
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NeoPixel Ring Clock is a clock which displays the time as a series of colored arcs.
Hours are represented by red, minutes by green, seconds by blue. The arcs overlap and the colors mix. Minutes and seconds are each represented by a single green or blue LED, respectively. In the 12 hour version, a single red LED represent 24 minutes.
More information is available at the tutorial on the Adafruit Learn site