It seems, that there is no driver for fan in armbian. So I wrote a little program in C to control fan on the hat. This nice program adjust the fan speed on cpu temperature accordingly. It starts the fan as 60 °C with 30% power. At 70 °C up to 60% and at 80 °C to 90%. You can adjust it within the code easily.
Compile it with "gcc fancontrol.c -o fancontrol". I configured the program as service. If you want it too, do the following steps:
Create a file fancontrol.service with the following content:
[Unit]
Description=Fan control
[Service]
Type=simple
User=root
Group=root
WorkingDirectory=/usr/bin
ExecStart=/usr/bin/fancontrol
[Install]
WantedBy=multi-user.target
do the following steps
sudo cp fancontrol /usr/bin
sudo cp fancontrol.service /etc/systemd/system
sudo systemctl enable fancontrol
sudo systemctl start fancontrol
and that's it.
It works perfekt for me.
Have fun.
