Controlling brushless fan without PWM on Fysetc Spider

General Discussion
1

I have this 24V 5015 brushless part cooling fan that I want to control with Fysetc Spider v1.1 board. I confirmed that the fan is voltage controlled(not PWM) by testing it with an adjustable PSU in isolation. I connected the fan to FAN0 header on the board and set the fan section in printer.cfg as:

[fan]
pin: PB0

Fan only works at 100% at full speed. Is there a way to disable the PWM on FAN0 and control with increasing/decreasing the voltage only? I managed to somewhat make it work by trying different values for cycle_time but it is not optimal.

2

Unfortunately that isn’t the way these boards work. The fan outputs are connected to mosfets, and they control fan speed by switching the ground on and off at the specified frequency and duty cycle. This creates an average voltage to reduce fan speed, but you can’t actually adjust the voltage. The fan is always connected to 24V. Some fans can’t be controlled this way, and will simply not work with PWM.