c-guide

sudo apt update
sudo apt install libc6-dev libcap2 libcap-dev
sudo adduser $USER kmem
echo 'SUBSYSTEM=="mem", KERNEL=="mem", GROUP="kmem", MODE="0660"' | sudo tee /etc/udev/rules.d/98-mem.rules
sudo reboot
cd
wget http://www.airspayce.com/mikem/bcm2835/bcm2835-1.60.tar.gz
tar zxvf bcm2835-1.60.tar.gz 
cd bcm2835-1.60/
sudo ./configure
sudo make && sudo make check && sudo make install
cd
sudo apt-get install p7zip-full
wget https://www.waveshare.com/w/upload/0/06/Fan_HAT.7z
7z x Fan_HAT.7z  -r -o./Fan_HAT
cd
cd Fan_HAT/c/
make clean 
make
sudo ./main

# A systemd unit
sudo vi /etc/systemd/system/pwm-led.service

# Paste the below, save and quit

[Unit]
Description=pwm-led
After=network-online.target

[Service]
ExecStart=/usr/bin/bash /home/pi/Fan_HAT/pwm.sh
Restart=on-failure
RestartSec=10
KillMode=process

[Install]
WantedBy=multi-user.target

sudo vi /home/pi/Fan_HAT/pwm.sh

# Paste the below, save and quit

#!/bin/bash
sudo /home/pi/Fan_HAT/c/main &

# At the end reload the daemon , enable and start the service

sudo systemctl daemon-reload
sudo systemctl enable pwm-led.service

#Restart Raspberry
sudo reboot