KVM Switch

Overview

A KVM switch lets one keyboard, monitor, and mouse (the "K", "V", and "M") run several computers from a single console. Four computers plug into the back, the console monitor, keyboard, mouse, and speakers plug into the front, and at any moment the switch routes one host through to that console. This unit handles four HDMI/USB hosts and switches the active one three ways: a front Port Select Button, the IR Remote, or a keyboard hotkey sequence the firmware watches for.

Everything routes through the Main Board. Video, USB, and audio arrive on the Port Bank at the rear, the Front Panel Assembly carries the controls and status LEDs, and the whole stack sits in a grounded steel Enclosure Assembly. An external adapter feeds the DC Power Jack, so the switch can power its console peripherals without leaning on any single host.

How it works

Each computer sends video into one of the four HDMI Input Port ports. The HDMI MUX Switch IC is a crosspoint switch: it passes the TMDS lanes of just the selected source through to the HDMI Output Port that drives the shared monitor, at up to 4K. The trick that keeps the other three machines happy is the EDID Emulator on each input. Even when a computer is not the active port, its EDID emulator keeps replaying the monitor's capabilities back to it, so the host never sees its display "unplug" and never reshuffles windows when you switch away.

Keyboard, mouse, and peripherals are handled the same way on the USB side. Each host links to a USB-B Host Port port, and the USB Hub Controller IC re-attaches the console devices on the USB-A Console Port ports to whichever host is selected. Audio follows through the Audio Jack pair. The Microcontroller is the conductor: it reads button presses, decodes commands from the IR Receiver Module, scans the keyboard stream for the hotkey, then commands the video MUX and USB hub to move to the new port and lights the matching Status LED.