USB-KVM

Turn an ordinary USB Switch into a full KVM by polling and monitoring USB connect/disconnect events and sending DDC/CI signals to switch display input according to a configuration file.

Installation

git clone https://github.com/joermo/usb-kvm.git
cd usb-kvm
python3 -m venv ./venv
source ./venv/bin/activate
pip install -r requirements.txt

This script requires read/write access to /dev/i2c devices. If you're on linux, proceed with creating a new group and assigning to yourself by following the below instructions. Else you can run the script as root, or assign temporary access via sudo chmod a+rw /dev/i2c-*.

sudo groupadd i2c
sudo chown :i2c /dev/i2c-*
sudo chmod g+rw /dev/i2c-*
whoami | xargs sudo usermod -aG i2c
sudo -i
echo 'KERNEL=="i2c-[0-9]*", GROUP="i2c"' >> /etc/udev/rules.d/10-local_i2c_group.rules

Configuration

KVM is configured via the following configuration structure:

{
    "usb_device": "6048:772",
    "monitors": {
        "1": {
            "on_connect_input": "DP1",
            "on_disconnect_input": "HDMI1"
        },
        "2": {
            "on_connect_input": "DP1",
            "on_disconnect_input": "HDMI2"
        }
    }
}

• usb_device is the USB device ID that is polled intermittently to update the connected monitors depending on its connected status.
• monitors represents the list of monitors connected/to be updated by the script
• on_connect_input is the monitor input to use when the USB device is connected to the host
• on_disconnect_input is the monitor input to use when the USB device is NOT connected to the host

The monitors must be in order that the script setup detects them in. For more information, see -f in the arguments section.

Arguments

-h  :   Display argument help
-f  :   Run KVM in device finder/setup mode. Follow the displayed prompts to complete initial setup and create KVM config file.
-d  :   Enable compatibility 'dumb monitor' flag. Some monitors will not properly display the currently used input option over DDC/CI, so logic based on the current input selection cannot be leveraged. Hence, this will ensure the correct input selection is set. Will cause initial screen flicker upon startup.
-c  :   Specify the KVM config directory. If not provided, use ./config.json.
-v  :   Use this flag to enable verbose logging of monitor sources when switching.

• Using -f for initial configuration to remove any annoying guesswork is highly encouraged.
• If monitor inputs only switch once and won't switch back, try using the -d flag alongside -v.

Running script directly

python3 kvm.py

Packaging script into executable

Some may find it helpful to package USB-KVM into a standalone executable for ease of running. Do so via the following:

pip install pyinstaller
pyinstaller --onefile kvm.py

Diagram