DellKnobVolume

Small Swift utility that listens to a Dell USB volume knob over HID and adjusts the system output volume on macOS.

Requirements

• macOS 12 or newer (tested on Apple Silicon)
• Xcode Command Line Tools (for swiftc)
• Tested with the Dell SK-8135 keyboard knob; other HID consumer-control devices may require minor adjustments.

Download

Clone or download this repository:

git clone https://github.com/saygonka/DellKnobVolume.git
cd DellKnobVolume

If you downloaded a ZIP, unzip it and open the folder in Terminal before continuing.

Build

Compile the tool with the required frameworks:

swiftc main.swift -framework IOKit -framework CoreAudio -o DellKnobVolume

This produces the executable DellKnobVolume in the project directory.

Run

Launch the binary directly:

./DellKnobVolume

You should see:

Running. Rotate the knob to change the volume (5% step).

Keep the process running while you use the knob.

Debugging

To inspect HID traffic, enable debug logging at build time:

swiftc main.swift -framework IOKit -framework CoreAudio -o DellKnobVolume -DDEBUG
./DellKnobVolume

When compiled with -DDEBUG, the program prints any unhandled HID usage pairs so you can extend the switch statement if your device exposes different controls.

Autostart on Login (LaunchAgent)

1. Build the binary and copy it to a persistent location, e.g.:

   mkdir -p ~/Applications/DellKnobVolume
   cp DellKnobVolume ~/Applications/DellKnobVolume/

2. Create a LaunchAgent plist at ~/Library/LaunchAgents/com.example.dellknobvolume.plist with the following contents (update the paths to match your setup):

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
   <plist version="1.0">
     <dict>
       <key>Label</key>
       <string>com.example.dellknobvolume</string>
       <key>ProgramArguments</key>
       <array>
         <string>/Users/your-user/Applications/DellKnobVolume/DellKnobVolume</string>
       </array>
       <key>RunAtLoad</key>
       <true/>
       <key>KeepAlive</key>
       <true/>
     </dict>
   </plist>

3. Load the agent:

   launchctl load ~/Library/LaunchAgents/com.example.dellknobvolume.plist

The utility now starts automatically each time you log in. To unload it later, run:

launchctl unload ~/Library/LaunchAgents/com.example.dellknobvolume.plist