====== Cooling Fan ======

===== Introduction =====

This page introduces the [[https://www.khadas.com/product-page/3705-cooling-fan | Cooling Fan]]. The first section describes how to control the fan on Ubuntu, and the second section describes how to control it on Android.

===== Ubuntu =====

<WRAP important>
This setting is only applicable to 4.9, 5.15, 5.4, and 6.1 linux kernel
</WRAP>

==== Fan Application ====

This method is recommended if you are using a desktop OS. Find ''Fan Setting'' in the applications list. Open the app to control the cooling fan speed.

{{/products/sbc/common/accessories/gnome_application_fan.png|gnome_application_fan}}


==== Command Line ====

You can also use commands to control the fan from the terminal.

=== Set the fan mode ===

^ fan mode ^ command ^
| off | ''fan.sh off'' |
| on | ''fan.sh on'' |
| auto | ''fan.sh auto'' |

=== Get the fan mode ===

```shell
fan.sh mode
```

=== Set the fan speed ===

^ fan speed ^ command ^
| high | ''fan.sh high'' |
| mid | ''fan.sh mid'' |
| low | ''fan.sh low'' |

=== Get CPU temperature ===

```shell
fan.sh temp
```

=== Get and Set the trigger temperature ===

You can read the trigger temperature from the following nodes:

^ fan mode ^ trigger temp parameter ^
| low | ''/sys/class/fan/trigger_temp_low'' |
| mid | ''/sys/class/fan/trigger_temp_mid'' |
| high | ''/sys/class/fan/trigger_temp_high'' |

Example: Get the low trigger temperature:

```shell
cat /sys/class/fan/trigger_temp_low 
```

Example: Set the low trigger temperature to ''40'' Celsius.

```shell
echo 40 | sudo tee /sys/class/fan/trigger_temp_low 
```

<WRAP tip >
The trigger temperature only affects the fan when it is in auto mode. 
</WRAP>

=== Mainline linux ===

The fan is controlled automatically by the Linux thermal subsystem. Temperatures are in millidegrees Celsius.

Example: Get the auto trigger temperature:
```
cat /sys/class/thermal/thermal_zone0/trip_point_3_temp
```

Example: set the auto trigger temp to 40000 millicelcius
```
echo 40000 | sudo tee /sys/class/thermal/thermal_zone0/trip_point_3_temp
```

<WRAP tip >
To turn the fan off, set the trigger temperature to a higher value (e.g., 80000). \\
To turn the fan on, set the trigger temperature to a lower value (e.g., 10000).
</WRAP>

===== Android =====

Check system settings to control the fan.