Some details are specific for the device or device group the accompanying code was written for, thus they may or may not be applicable for other devices. The details described below apply to, but are not necessarily limited to, tinyAVR® 1-series.
The accompanying code includes support for adjusting the PWM duty cycle with the on-board button of the ATtiny817 Xplained Mini. Other than this, there is no specific hardware provided or described for this application note. For this reason, and the fact that BLDC motors and their control circuits come in many different varieties, two specific fan hardware layouts that will fit the described device setup are outlined below.