Trying the Blue Pill First

A project log for Raspberry Pi Powerbook

Replacing the guts of a broken Powerbook with everyone's favorite SBC

Dan JilekDan Jilek 06/24/2020 at 19:410 Comments

Now that the obligatory Matrix reference is taken care of...

I figured I would see if the matrix on this keyboard could be brute forced without having to take it apart (blue pill). As it turns out, yes it can... to a point. Here's what I have so far:

A quick note on the pin numbers: The spreadsheet uses the numbers as I see them on the breakout boards. Since the membranes are face to face, one of them is technically upside down, making the pin numbering backwards. That's a problem for another day.

The matrix is reasonably logical. I believe pins two and three on the bottom membrane are power and ground for the caps lock LED, but haven't tested that yet. As you can see, I'm missing a few keys still. After going over the potential combinations multiple times (including the supposed LED pins), I still haven't found tilde, F11, F12, enter, return, delete, backspace, R shift, either bracket, pipe, or +/=. Obviously that's a bit of a problem. It's easy enough looking at the spreadsheet to extrapolate where they probably are, but testing hasn't produced those results. Maybe the contacts are dirty or corroded. It would hardly be surprising given the amount of battery leakage on everything. Unfortunately finding out will require taking the keyboard apart, with putting it back together being the harder task given how it's constructed.

The plastic frame is held onto the aluminum base with dozens of plastic studs. Each stud is melted and spread out to form what is essentially a plastic pop rivet. That's all fine and good if you don't need to re-open the finished product, but a bit problematic for re-usability otherwise. I don't see a way around that, however, since I'm missing a bunch of keys from my matrix. It looks like my favorite plastic bonder is going to get some more use.