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.