Thursday, August 31, 2017

Micropad Rebuild

Genovation Parallel Micropad 621

I bought several of these on eBay. I got 3 of the Parallel 621 keypads and 1 of the Serial 623. They were a deal for $6 each. They are very old, the drivers available for them are for DOS and Windows 3.1.

It is a modular design and the controller board is easily removed. The matrix has an easy to access pin header. The matrix has diodes for full anti-ghosting.

They are in pretty good condition considering their age.

The switches are some generic clicky ALPS. The keycaps are doubleshot ABS.

The shell is held together with 4 screws hidden under the adhesive rubber feet.

The PCB assembly is held in place by another 4 screws.

The controller board is held on with double stick tape.

The 9 pin header is the 4 column x 5 row matrix connector.

From top to bottom the pins are:
  • Col 4
  • Col 3
  • Col 2
  • Col 1
  • Row 5
  • Row 4
  • Row 3
  • Row 2
  • Row 1
The diodes are oriented Row to Col.

I connected it to a Pro Micro with pre-made jumper wires.
  • D2
  • D1
  • D0
  • D4
  • C6
  • D7
  • E6
  • B4
  • B5

I taped the connectors together to keep them in order.

I soldered pin headers to Pro Micro. It is held down with 3M VHD heavy duty double stick foam tape.

The matrix is so simple I used to create the firmware hex. The JSON file I used is here.