The interfacing is courtesy of a Teensy microcontroller board as in so many other keyboard projects, but what makes this extra-interesting is the way the Coleco keyboard speaks to the world.

A previous Design Idea described a single-wire-plus-ground-return, keypad-to-microcontroller interface in which a single pulse represents each keystroke (Reference 1). The pulse's width is ...

The interfacing is courtesy of a Teensy microcontroller board as in so many other keyboard projects, but what makes this extra-interesting is the way the Coleco keyboard speaks to the world.

You can use a microcontroller that includes an ADC to design a two-wire-plus-ground keyboard interface. For example, you can use a resistive voltage divider to identify a pressed key (Reference 1). A ...