Pi PoE HAT fan control

Home Assistant OS
#1

I’ve installed Hass.io on my Pi 3B+ with the official PoE HAT but the fan ramps up to 100% for 10-20s every minute or so.

Raspbian seems to allow the fan to be controlled through a couple entries in the config.txt but this isn’t available in Hass.io.

Is it possible to control the fan in Hass?

#2

Yes it is.

#3

Where can I find it?

Raspberry Pi 4 on PoE-HAT: Getting hot and fan of PoE-HAT is never running
#4

In the boot partition.

#5

@nickrout, mind sharing the exact location? I can’t find it.

#6

I had the same issue and it was driving me crazy… After searching online and in here, I was able to resolve it. To edit config.txt, I shut down my pi and pulled the SD card and opened it up on my PC. From there I was able to open config.txt and at the bottom of the file I simply added

## poe_fan_temp
##    temp0 is lower speed fan, temp1 is high fan speed.
##    Current setting is fan turns on at 70C, turns off when it comes back down to 65C.
##    If the temperature reaches 75C it will go full blast until it drops back down to 70C. 
dtparam=poe_fan_temp0=70000,poe_fan_temp0_hyst=5000
dtparam=poe_fan_temp1=75000,poe_fan_temp1_hyst=5000

The fan hasn’t kicked on since I powered the unit back up about an hour ago… but I’ll probably play around with these settings slightly after monitoring the temp for a while.

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Increase Raspberry Pi PoE hat fan threshold
#7

Thanks for the help!

I managed to edit the config.txt - it turned out that my linux machine wasn’t mounting the fat32 boot partition so I had to fire up a windows machine.

#8

After running for close to 48 hours and not having the fan kick on… I decided to drop my setpoints down a bit. My high temp was 67.4C and overnight it hovered around 56C so I went with

## poe_fan_temp
##    temp0 is lower speed fan, temp1 is high fan speed.
##    Current setting is fan turns on at 63C, turns off when it comes back down to 60C.
##    If the temperature reaches 66C it will go full blast until it drops back down to 63C. 
dtparam=poe_fan_temp0=63000,poe_fan_temp0_hyst=3000
dtparam=poe_fan_temp1=66000,poe_fan_temp1_hyst=3000
#9

Since updating to HassOS 3.13, I’ve noticed that the fan on the POE HAT seems to be ignoring the dtparam’s as shown above.

Anyone else noticing this?

EDIT: I’ve just looked through the release notes and can only assume that something changed in the latest RPi kernel.

#10

@thatguy_za I’ve noticed the same thing - have you found a fix?

#11

After a fair amount of trial and error, the only thing that worked was having three poe_fan_temp’s. Unfortunately I can’t remember my exact temps but these should help:

dtparam=poe_fan_temp0=63000,poe_fan_temp0_hyst=3000
dtparam=poe_fan_temp1=66000,poe_fan_temp1_hyst=3000
dtparam=poe_fan_temp2=75000,poe_fan_temp2_hyst=3000
#12

Actually 4 lines of code are needed and basically what you input is the curve of how the fan reacts to temperature in a proportional way. More info can be found here:
RaspBerry Pi GitHub
And here:
HASS OS GitHub
I appended these lines at the end of config.txt

dtparam=poe_fan_temp0=10000,poe_fan_temp0_hyst=1000
dtparam=poe_fan_temp1=55000,poe_fan_temp1_hyst=5000
dtparam=poe_fan_temp2=60000,poe_fan_temp2_hyst=5000
dtparam=poe_fan_temp3=65000,poe_fan_temp3_hyst=5000

My fan is now constantly on but at low speed and will speed up when needed (CPU load up -> temp up -> fan RPM up). A constantly switching fan is not preferred over one that is constantly on (at low speed).

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