FAN ports confusion with btt skr mini e3 v2

I must say this is a mind blowing investigation for me.
I'm experiencing problems with pwm for fans in ender 3 pro using btt skr mini e3 v2.
LCD has two options, one is controller fan, controlled via menu, the other is on the main info screen showing fan with percentage, and that corresponds with the part cooling fan commands m106 and shows correct information.
the part colling fan tough, is always on 100% no matter what the info screen says

looking at the code, i can only see fans on ports pb6 pb7 and not pc6 pc7 as they should be,
the configuration files for the specific board shows -1 for fan ports

what am i missing here? where is the port configuration for the fan ports on that board's firmware?

Edited 2 time(s). Last edit at 03/23/2025 10:42AM by Ran2me.

??
[github.com] shows

#define FAN0_PIN                            PC6

and
[github.com] shows

#define FAN1_PIN                            PC7

FAN_PIN (FAN0_PIN in newer code) is always the part cooling fan.
You set the Controller fan in Configuration_adv.h
#define CONTROLLER_FAN_PIN FAN1_PIN // cannot be fan0_pin

Edited 2 time(s). Last edit at 03/23/2025 11:34AM by Dust.

Wow
It looks like I’m the electronic engineer with the poorest knowledge in code.
I searched in the configurations files and did not realize what’s going on.

So now that I know that the configuration is ok, I need to solve the issue, why are the m106 commands, that looks ok on the info screen (0% for initial layer and then 25% and so on) are not reflecting to the part cooling fan, that stays on 100% all the time…

Controller fan, btw, can be controlled from the menu, and I can also hear it automatically turns on and off according to the on board temperature sensor, when the steppers work hard.

You may have noticed that the fan mosfets control the gnd line, as such you cannot share fan gnds with other fixed gnd lines. a short to real gnd and the fan will always be on.


Step one would be to unplug the fan and stick a probe or meter in the fan port using both pins. and play with M106/M107 gcodes

Thanks again,
So I guess you may think that the issue is blowen mosfet (I read about this issue in these specific boards)