For basic information on how to use GPIOs in CircuitPython, refer to this great tutorial from Adafruit.
What GPIOs are available?
We assume you know how to get to REPL. To get the list of GPIOs on your board enter these commands in REPL:
See some simple example in a video
You will get a list of the identifiers on how to call each GPIO for your controller. These identifiers are what you need when defining the connections to the keyboard.
Test Outputs: LEDs
The easiest way to test your board and LEDs is to use a simple blink program. You can modify the
LED Setup section to select the GPIO where your LED is connected to the board. Change
board.RED_LED to the GPIO you want to test. Try the example below by changing the pin definition
Once running, you should see the LED blink at a rate of once per second.
Test Inputs: Switches/Buttons
To help test and identify the GPIOs connected to Switches (ones directly wired between the GPIO and GND), you can use the following program and modify the
LED Setup and
Switch Setup sections. Run the program above to validate that there is a LED on the GPIO you select.
Try the example below by changing the pin definition
By pressing the switch, you will turn on the LED. See a similar example in a video
PWM Video example: here