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ckamps asked

Enabling PoE+ HAT fan on Raspberry Pi 4

How can I enable and control the fan on the official Raspberry Pi POE+ HAT on a Raspberry Pi 4 B running Venus OS 2.73?

I am running the Raspberry Pi in an off grid mode in an enclosure.

I’ve noticed that POE HAT fan does not appear to operate when using Venus OS. I’ve attempted to configure the fan speeds via /u-boot/config.txt per standard Raspberry Pi setup instructions, but that approach doesn’t appear to be compatible with Venus OS.

# cat /u-boot/config.txt
# PoE Hat Fan Speeds
dtoverlay=rpi-poe-plus
dtparam=poe_fan_temp0=50000
dtparam=poe_fan_temp1=60000
dtparam=poe_fan_temp2=70000
dtparam=poe_fan_temp3=80000

I downloaded the rip-poe-plus overlay file from here:

# cd /u-boot/overlays; wget https://github.com/raspberrypi/firmware/raw/master/boot/overlays/rpi-poe-plus.dtbo

However, after a reboot, I see this error via dmesg:

# dmesg | grep poe
[    2.980550] rpi-poe-fan rpi-poe-fan@0: Failed to get default PWM value: -5
[    2.988243] rpi-poe-fan: probe of rpi-poe-fan@0 failed with error -5

Googling this error, I see a lot of references to a bug in one of the kernel versions that has since been fixed. However, I don’t know how that issue might relate to the kernel that Venus OS is using.

I also tried to use the rip-poe.dtbo overlay with the same error messages in the dmesg output.

Since I see that a kernel module for the POE fan is installed, I’m holding out hope that there’s a means to enable and configure the POE fan when using Venus OS:

# opkg list-installed | grep poe
kernel-module-pppoe-4.19.81-v7l - 4.19-r0
kernel-module-rpi-poe-fan-4.19.81-v7l - 4.19-r0

Concern over excessive heat come summer

I am concerned that the heat may be excessive in the summer months.

Temperatures recently obtained in a winter month via the following command range from 60-74 C:

# watch cat /sys/class/thermal/thermal_zone0/temp

Based on my research thus far, the Raspberry Pi should be OK running at 70 C, but I’d like to reduce the overall temperature in the enclosure if feasible. (I am planning to add two air vents to the enclosure and potentially a fan).

Alternative: Ditch the PoE+ HAT and use a 12V DC to USB C Converter

My default alternative path is to get a converter to take my 12V DC power from the solar system and convert it to USC C to directly power the Raspberry Pi.

Venus OSRaspberry Pioffgridfan
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2 Answers
sekurit avatar image
sekurit answered ·

Any news on how to enable the fan of the poe plus hat? Seems like I have the same problem... and it sounds like you managed to activate it in one of your other questions!

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pulith avatar image
pulith answered ·

@Kevin Windrem do you this there is a way to on the fan hat from venus. might need a package for it :)

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