Joe Scotto's Latest RP2040 Keyboard Build Has a Poorly Hidden Secret: It's Actually a Mouse

Home-brew keyboard enthusiast Joe Scotto has created his first design which doubles as a functional mouse — turning four of its six keys as a four-way direction pad to move the cursor.

"This is the ScottoMouse, a six-key macropad that uses QMK [firmware] mouse keys to emulate a mouse," Scotto explains. "Like most of my builds, it's handwired — but this one is 'direct pin' meaning each switch just gets an individual pin on the controller and then they all share a common ground. The controller I chose is complete overkill but it's the Raspberry Pi Pico. Finally for the the switches, I figured for a joke of a board I would use a joke of a switch… Cherry MX browns."

The unusual layout of the 3D-printed housing has two keys placed beneath a panel reading "THIS IS A MOUSE," with a further four in a curving arc stuck off to the side. The device may present itself to the host system as a mouse, but you won't find an optical sensor or even a classic rolling ball: instead, the mouse functionality is controlled wholly from the mechanical switches.

"The four main buttons move the mouse left, up, down, right (in that order) and then the two thumb buttons are left click and right click," Scotto explains. "I also implemented a few combos, so if you press both left and right at the same time you will get middle click. Scrolling is done by the same combo except you then add up or down depending on how you wish to scroll.

This is far from Scotto's first hand-wired keyboard build. Late last year the maker showed off a fully-split ergonomic design powered by a single Arduino Pro Micro in one half, with the other connected using a repurposed VGA cable. The ScottoErgo, meanwhile, used a similar split layout but in a single chassis with a Raspberry Pi Pico as its controller — but one which had its micro-USB connector removed in favor of a considerable more robust GX16-4 aviation connector.

The ScottoMouse joins all of Scotto's earlier input device designs on GitHub, under the reciprocal Creative Commons Attribution-NoCommercial-ShareAlike 4.0 license. More information is available on Scotto's website.