Fails to read tach or set pwm on Ubuntu 24.04 #5
Description
I am trying to read and/or control the PWM fan speed on my compute blade STA fan unit. The blade hosts a CM5 Lite running Ubuntu 24.04 (Noble Numbat).
Reading fan speed fails on both blades that are connected to the STA fan unit:
user@host:~/compute-blade-pwm-fan-control$ sudo python3 read_fan_speed.py
0 RPM
0 RPM
0 RPM
...etc
Setting the fan speed with control_fan.py also seems to have no effect.
I suspect that Ubuntu is getting in the way somehow as the fans also report no events with gpiomon: user@host:~$ sudo gpiomon gpiochip4 13 though I may be misunderstanding how gpiomon works/interacts with pins that are in "PWM mode".
The fans continue to run even after the blades are shutdown (as long as they still have POE power). I guess this is because they are still getting 5V, though I did expect them to stop if both connected blades are shut down.