Document the use of 3 pin PWM + Tach fans with EBB

It would be great if the use of 3 (or even 4) pin PWM + Tachometer fans could be documented.

For example - is it "safe" to use the PA0 (FAN0/1 header) for +/- and a single pin from the I2C header, say PB4 for the sense/pulse yellow wire? Are there any risks?

Personally I've noticed when wiring a 3 pin fan up like this the fan never stops spinning at idle, there must be some sort of current / loop occurring when adding the PB4 to the sense/pulse connection.


For context - It's generally a good idea to use a fan with a tach for your hotend cooling to avoid potential disasters should it fail or become blocked during a print - for example: https://ellis3dp.com/Print-Tuning-Guide/articles/useful_macros/hotend_fan_monitoring.html

Start with the issue's wiring diagram and the EBB pin/header documentation, focusing on PA0, PB4, PWM, and tachometer connections. Determine whether the proposed wiring is safe and why the fan may keep spinning at idle, then document supported wiring, risks, and expected behavior.

Written by the indexing model from the issue text.