Unhackable Arduino Switch Matrix -- Episode 456

The other day at the hackerspace Dave was talking with members how to improve the safety in the space. Especially how to prevent other people from leaving dangerous devices running unattended. They quickly came up with a button that needs to be pressed once in a while, or otherwise the machines power would be shut off. Since it's a hackerspace the expectation of people building crude "Arduino with servo" devices to circumvent such a device was high. But having a 4x4 button matrix that would indicated a random button to press sounded tougher to get around, so the idea for this project was born. It also looks suspiciously like a midi-controller.

Bill of Materials

Product Name	Manufacturer	Quantity	Buy Kit
ABX00028 - NANO EVERY DEVELOPMENT BRD, 8BIT AVR	ARDUINO	1	Buy Now
1403010049 - 3D Printer Filament, 1.75mm Dia, White, PLA	FILAMENTIVE	1	Buy Now
1403010042 - 3D Printer Filament, 1.75mm Dia, Black, PLA	FILAMENTIVE	1	Buy Now
1403010037 - 3D Printer Filament, 1.75mm Dia, Orange, PLA	FILAMENTIVE	1	Buy Now
Rotary Potentiometer, Conductive Plastic, 100 kohm, 1 Turns, Antilog, 200 mW, ± 20%, P160 Series	TT ELECTRONICS / BI TECHNOLOGIES	4	Buy Now
Tactile Switch, B3F Series, Top Actuated, Through Hole, Round Button, 100 gf, 50mA at 24VDC	OMRON	64	Buy Now