As I dive into the Mark II changes the choice of display is at the top of my list. Why? Because the dimensions of the device dictate a lot about the case dimensions and until that's sorted I can't complete the design of the printable parts.
What I know for sure is that I want something with an i2c interface. I learned the hard way that adapting an i2c "backpack" to a display it wasn't designed for is not the path to happiness and while it might be possible, solving that particular problem isn't something I want on the short path I have to getting to something that works (May 1st!).
Another constraint I'm throwing-in is that the display be compatible with Micro/CircuitPython, because as much fun as writing drivers for either of those is (I've done a few), it's time-consuming and if I need to purchase a display anyway, why make it any harder on myself than it has to be?
What I haven't decided is whether or not this should be a character or graphical display. My instinct is to go with a character display like the one I already have because it seems like this would put far less demand on the limited resources of the CPU/memory of the main processor, but my initial searches for parts is indicating that my options for a character display with the dimensions I'm interested in may be limited.
Not so fast...
Maybe I can use the LCD I already have if I skip using i2c and go direct. I just found this example of using such a display with an Arduino and it only takes one more GPIO to drive the 4x40 display than it does to drive the smaller ones, something like a total of seven lines?
If that's right, it's not a lot more than the i2c backpack I've been using which only provides a single enable line (which is probably why I couldn't get it to work).
I might try this out and see if I can get the original LCD to work. The only kink I can think of is voltage mismatch between the ESP32 board and the LCD (I can't remember off-hand if the LCD is 5V or 3.5V).
Jason J. Gullickson, 2026