Colour picker

A NeoPixel stick (8 LEDs, DIN on GPIO18, 5 V) and a button on GPIO17 (to GND, use the pull-up). The stick starts off. Each press moves the whole stick to the next state:

red (255, 0, 0) → green (0, 255, 0) → blue (0, 0, 255) → off → red → …

The test presses at 1, 2, 3, 4 and 5 s.