Update README.md

README.md

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 # RPiPWMFanControl
-Pwm fan control for raspberry pi in golang
+Fan control based on cpu temp for raspberry pi using hardware PWM.
+
+## Setup/Install
+Download the `rpi-pwm-fancontrol` binary from [releases](https://github.com/Ykrej/RPiPWMFanControl/releases) or build the program yourself with the `build.sh` script.
+
+NOTE: Running the program as non-root silently fails to control the pwm signal. Please open an issue if you find a solution to this.
+
+### Configuration
+All configuration is done through the command line interface.
+
+The default `--freq` value works for the Noctua NF-A4x10 5v PWM fan but is likely to require a different value for different fans/brands.
+
+This set of options could be out of date. Check the output from `rpi-pwm-fancontrol --help` for up to date options.
+``` 
+Usage of /usr/local/bin/rpi-pwm-fancontrol:
+  -freq uint
+        PWM control frequency in Hz (default 25000)
+  -gpio uint
+        GPIO pin number for PWM control (default 18)
+  -max-temp float
+        Temperature (°C) for max fan speed (default 55)
+  -min-speed uint
+        Minimum fan speed as a percent from 0 to 100 (default 30)
+  -poll uint
+        Polling rate in milliseconds (default 500)
+  -start-temp float
+        Temperature (°C) to start fan (default 40)
+  -stop-temp float
+        Temperature (°C) to stop fan (default 35)
+  -version
+        List version info and exit
+```
+
+### Systemd/Autostart
+To get the program to run on startup I use systemd.
+1. Copy the binary to `/usr/local/bin`
+2. Create the following systemd service at `/etc/systemd/system/rpi-pwm-fancontrol.service`. Edit the configuration on the ExecStart value as you see fit.
+```ini
+[Unit]
+Description=controls the pwm fan based on cpu temp
+
+[Service]
+Type=simple
+User=root
+Restart=always
+RestartSec=3
+ExecStart=/usr/local/bin/rpi-pwm-fancontrol
+
+[Install]
+WantedBy=multi-user.target
+```
+
+3. Start the service
+```bash
+sudo systemctl daemon-reload
+sudo systemctl enable rpi-pwm-fancontrol.service
+sudo systemctl start rpi-pwm-fancontrol.service
+```