After much iteration on the firmware for the keyboard, I decided on finally assembling the device, in spite of not being completely finished. It will continue to be a work-in-progress, but I need to move on to other projects for now. Once I finish some other projects, I’ll come back to this one.
On and off, I’ve been working on a project to build a learning toy for my son. It started out in various forms, but is now destined to become embedded within an old PS/2 keyboard I’ve had lying around unused for a good while (except as an occasional toddler plaything). At any rate, I needed a display of some sort to permanently embed in the project, and since it will likely take a beating over time, I wanted it to be fairly inexpensive. I ended up finding this device on Amazon, and finally received it last week.
Using Adafruit’s ST7735 library, it works perfectly. Thanks to the blog post here, I was able to set it up fairly easily. Here, you can see it hooked up to my Adafruit Pro Trinket. The only addition I had to make was to insert a LD33CV 3.3V voltage regulator between the Trinket’s power supply and the bread board’s power bus. The product claims that it has a built-in level shifter, but the data sheets have conflicting information about this. Better safe than sorry. Once the project is more complete, I plan on swapping the Trinket out for a dedicated ATMega328P, and will give it a lower voltage power supply also.