shit.cx

Wiring Up the Keyboard

2021-01-16T20:19

This week, I've spent a few evenings wiring up my keyboard.

I described the circuit a few weeks ago.¹ It's not too difficult. It just requires perseverance and a little skill with a soldering iron. All up, I probably spent four hours.

I did the job in three sections; wiring the rows, then the columns, and finally connecting it to the Teensy.

Wiring the rows was easy. A strip of uninsulated wire running the length of a row of keys with a leg of each key soldered to it.

Rows

Between each switch and column, there needs to be a diode. I also double-checked I had the polarity correct by connecting a button to my one-button configured Teensy.² This was fortunate because I had it wrong (though, this problem can be mitigated by calling a column a row and a row a column).

With this keyboard I took a shortcut that I hope doesn't come back to bite me. I noticed that the uninsulated wire was quite ridged. The columns could could bridge the rows with an air gap preventing the need to insulate every wire or cover the rows in some sort of insulating tape which would make future repairs harder. And once it's closed up, the risk of a short is all but gone. I connected two switches together with diodes in a V pattern. Six rows of switches resulted in three V's of diodes. The columns then ran between the points of the three V's.

Columns

Then I wired it all back to the Teensy, tucked the wires away and went to bed.

Connecting the Teensy

All done

¹ Keyboard Circuit

² Keyboard Firmware

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