MegaHack Hardware ATmega168 (Datasheet) 8 x Max7219 (Datasheet) with 8x8 dot matrix displays Switch of a very old Logitech mouse Pinout MAX7219 CS: PB2 MAX7219 DIN: PB3 MAX7219 CLK: PB5 Green LED: PB0 Yellow LED: PD7 Red LED: PD6 Input switch: PB0 Software AVR Crosspack for macOS