The three white notes surrounding the two black keys are C, D, and E, and the four white notes surrounding the three black keys are F, G, A and B. So, if you count eight keys right from Middle C (or, ...

A man playing a piano built to the DS5.5 standard, with narrower keys than a conventional piano, plays an octave with a relaxed right hand and reaches a flat-eleventh chord with his left hand.

It’s responsible for reading the state of five 3D printed piano keys: three white, two black. It’s nowhere near a full octave, but for a doorbell, it’s enough.