These sections present helpful tips and notes not included in general documentation.
Outputting a debug value in a quasi-serial protocol, over a single output pin, can be an effective debugging method.
So now you've got that LED to blink, signifying that something is running in your MCU. But you'd like a little more information from your prototype system: perhaps some indication of which code paths are executing and which ones are not. One-way communication would suffice...