Hi Han.
Are you talking about this image:

It uses GPIO 16 for the LED and GPIO 4 for the button.
These are the GPIOs used in the code:

const int buttonPin = 4;    // the number of the pushbutton pin
const int ledPin = 16;      // the number of the LED pin

Or are you talking about something else?
Regards,
Sara

Very confusing when you start unit 2 with a 30 pin version and in unit 7 you use the same pins but they are in a different place, because (without telling anybody) switched to the 36 pin version.

Hi Han.
You are right. We need to change some schematics so that all use the same number of pins.
We’ll take that into account in the next course update.
Thank you for pointing that out.
Regards,
Sara