I’m planning on repurposing some lighted switches for a control surface. Unfortunately, the builtin lamp-sockets have only two leads, and I’d like to install bicolor LEDs.
Would it be possible to redesign the peggy circuit to run the LED drivers as both sink and source (probably adding some logic to prevent two transistors on the same row from being open at the same time)? Even if it requires a more expensive LED driver chip, the amount needed would be halved.
I don’t see any straightforward way to do this with the same basic architecture, if it has to work with two-pin LEDs. There are, of course, ways to do it, but it would require a very different design, since both the row and column drivers assume that one side is high, and one is low.
If we were to build a Peggy variant that took discrete bicolor LEDs, we would design it so that it took common-anode 3-pin bicolor LEDs. That would be a very straightforward modification.