Computer

Generic matrix keyboard

Last Updated or created 2022-11-08

In this case designed for my 6502, but it is a generic setup.

I it just a dual 16key matrix decoder merged together. You can probably use this with raspberries, arduinos etc.

I wanted to use 74C923 but these are nowhere to be found. And even then, the number of keys wil be 20.
So i am tying together two 74C922 using some logic in a PLD.

First draft

It wil be something like above. Using the data availabe signal i can combine both 16key matrixes. (In theory .. it is all untested)

PLD Code

GAL22V10
Address Decoder

PHI2 DA0 DA1 D01 D02 D03 D04 D11 D12 D13 D14 GND
NC D0 D1 D2 D3 D4 DA NC NC NC NC VCC

DA = DA0 + DA1
D0 = D01 & DA0 + D11 & DA1
D1 = D02 & DA0 + D12 & DA1
D2 = D03 & DA0 + D13 & DA1
D3 = D04 & DA0 + D14 & DA1
D4 = DA1 

DESCRIPTION
Key matrix merger

I’ve got my new keys of the keyboard in today!

  • 0-F – hex keys
  • G = Go
  • R = Reset
  • S = Step
  • M = Memory
  • Cursor keys (up/down for memory locations)
  • ??? I’ve got room for 8 more keys

My inkscape template (keys are 10/10mm)

Printed on white and red paper

https://media.henriaanstoot.nl/keyboardmatrix.svg