Fan Control via cur_state file.

[russelroyr]

Greetings,
Thanks for this python file.

I’ve examined the fan_control.py. I did not install it yet.
Looks like you control the fan speed via the cur_state file.
When I change this file manually (vi), the fan spins for maybe 30 seconds and then stops.
When I look at the value in the cur_state file it’s set to 0.
Do you know why it behaves this way?

Does the fan continue to operate with your script because you periodically set the cur_state value otherwise it would stop like when I adjust it manually?

Russ

[vijaygill]

@russelroyr - the logic (very high level) is

• the main loop runs every 15 seconds (5 seconds if DEBUG environment variable is set).
• it calls adjust_fan() function
• adjust_fan function gets current temperature and calls adjust_speed_based_on_temperature
• adjust_speed_based_on_temperature then tries to set speed by calling set_fan_speed with the desired state (ranging from MIN_STATE (hard coded to 1 and upto max_state which is determined by the device itself. On my cm3588 it is 5)

When you say you changed the file in vi, what exactly did you change? In my case I set MIN_STATE to 1 because I wanted the fan to run always (even at lowest speed). But if you set it to 0, the fan will actually stop when the temperature falls below lower temperature threshold.

And no, the cur_state does not have to be continously set to keep the fan running. Just set it once and the fan runs until you change the value or reboot the board.

You can run this script in debug mode and in foreground by just running it like any standard python script.

This should show what the program is doing by log messages.

All those "logger.debug" messages should tell you what's going on.

Let me know how it goes.

[vijaygill]

@russelroyr - I have added more comments to the code.

[russelroyr]

So, just to be clear, I'm not running your fan_control.py script.

All I did was change the cur_state file from 0 to 3. When I do that I see the fan runs, which makes sense. It only runs for like 30 seconds.

Then it stops.
When I go and examine cur_state file it's set back to 0. What set it back to 0?
Something (the system?) is writting it back to zero stopping the fan.

I can go back and change the cur_state file to 4, fan runs for a bit and then stops. The cur_state is set to 0 again.

What I expect is the cur_state file to remain at the value I set it to AND the fan to keep spining.

Russ

[vijaygill]

I have not seen this behaviour. I am running armbian.
What flavour or os are you running?

Mine is

pi@cm3588-nas-01 ~ $ lsb_release -a
No LSB modules are available.
Distributor ID: Debian
Description:    Armbian 25.2.3 bookworm
Release:        12
Codename:       bookworm
pi@cm3588-nas-01 ~ $