There is documentation for the built-in library (“cpx”).
Start with
https://circuitpython.readthedocs.io/projects/circuitplayground/en/latest/index.html
The actual reference is:
https://circuitpython.readthedocs.io/projects/circuitplayground/en/latest/api.html
Programmers will be slightly annoyed, as it doesn’t follow conventions we are used to.
People, however, will appreciate the pictures, examples, and explanation.
awgrover 