Expanding SKR 1.4 fan PWM controllers?

Okayyyy, so I thought, let's venture out into creating a PWM expander. This is how far I got, and it works great with an Arduino Uno:


It's this schematic but with an IRLB8743:


So I made a test setup and it works great, no voltage leaking through the little circuit and I can control the fan speed through PWM with an Arduino Uno, but when I connect it to my SKR 1.4 it doesn't work.

I am using the P1_00 'PSU on' pin and have defined it in my pins in Marlin:

//
// Heaters / Fans
//
#ifndef HEATER_0_PIN
  #define HEATER_0_PIN                     P2_07
#endif
#if HOTENDS == 1
  #ifndef FAN1_PIN
    #define FAN1_PIN                       -1
  #endif
#else
  #ifndef HEATER_1_PIN
    #define HEATER_1_PIN                   P2_04
  #endif
#endif
#ifndef FAN_PIN
  #define FAN_PIN                          P1_00 // PSU on connection with DIY MOSFET for ABS slow fan
#endif
#ifndef HEATER_BED_PIN
  #define HEATER_BED_PIN                   P2_05
#endif

Also tried it as 'FAN1_PIN', but didn't make a difference.
Note that I'm already using #define E0_AUTO_FAN_PIN P2_03 for the hotend cooling fan because I needed PWM on it to make it a bit more silent and I wanted it to turn of when the hotend was below a certain temperature.

Somehow it doesn't want to turn on when setting for example M106 S200. I also tried selecting different fans in case it somehow thought this would be not FAN0 but FAN1. I double checked the wiring with the schematics of the board to make sure I was using the Sig (P1_00) and GND of the 'PWRDET' pins.

The only thing that might be is that the PWRDET Sig pin has a pullup resistor:


Does anyone know how to fix this? Should I try shorting out the 1k resistor in my schematic to compensate for the pullup/pulldown? (I still don't understand the pullup/pulldown concept completely).

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http://www.marinusdebeer.nl/

Update, I decided to remove the 1K resistor bridging the Sig and GND and now it works flawlessly.

If anyone has any remarks about my design anyway, let me know if I can improve on this and if it's actually safe to do. I'm still new to electronics and despite triple/quadruple testing everything I'm never a 100% sure if it's a good idea I'm having.

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http://www.marinusdebeer.nl/

What do you do?
Do you short connect GND and signal pins (1 and 3 on diagram)?

Quote
aleksandarpu
What do you do?
Do you short connect GND and signal pins (1 and 3 on diagram)?

Hi I'm sorry, it's been a while, I'll have to check out how I did it.. Sorry if my update was vague about what I changed exactly.

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http://www.marinusdebeer.nl/