While the Arduino family of boards connect to your computer using a USB virtual serial port, the ATmega ones have an actual serial connection on-board.

The idea early on was to leverage existing Arduino libraries to connect with a standard USB mouse, specifically, the hardware would take the form of an Arduino Mega 2560 with a USB Host Shield.

The Arduino cable tester is equipped with a touchscreen the Cable Tracer builds on a previous project that is now 70% smaller than its ...