We assume you already have Python 3 installed on your computer. Note we do not support Python 2 - it's deprecated and no longer supported!
At your command line prompt of choice, check your Python version with
If the install fails with text that ends with something like:
distutils.errors.DistutilsError: Setup script exited with error: Microsoft Visual C++ 14.0 is required. Get it with "Microsoft Visual C++ Build Tools": https://visualstudio.microsoft.com/downloads/
then you will need to also install the Microsoft Visual C++ Build Tools. Thanks to @jklem for pointing this out in the forums.
Download it from here (same link as in text):
NOTE: You do not need the full Visual Studio IDE. Just the Build Tools.
This downloads a .exe file with a name like vs_BuildTools.exe. Run that to install the build tools and then try the pip install again.
You must do this every time before running circuitpython code, you can set it permanently in windows if you like, for now just type into the same cmd window you're using with Python
If you are using Windows Powershell, the syntax is a little different. In that case do:
In the same command window you
set BLINKA_MCP2221=1 env var, run
python and run
at the Python REPL. If you get no errors, and you see a list of all the pins available - you're good to go!