Teensy Thumb Keyboard

I found this LCD on Aliexpress and it's about the same width as the Teensy Thumb Board:

https://www.aliexpress.com/item/20PIN-SPI-COG-12864-LCD-Module-with-Chinese-Font-ST7567R-Drive-IC-3-3V-White-Backlight/32608104073.html

I ordered a couple and tried it out with u8g2 library. It mostly worked but needed a couple tweaks. Pull request merged now and everything is working nicely. The display has support for 4 color grayscale but u8g2 only supports black and white at the moment. Anyone know a free to use driver? Maybe I'll get around to writing one that supports grayscale.

Anyway, prototype faceplate integrated with the LCD is shown below. All the keys aren't mounted yet but the screen looks great. Way better than the ti-81.

Visibility with the back light off is great too. Pictured next to a 6" phone for size comparison.

Here it is with all the keys on.

Case backs are always the hardest to design. This is a test one with a good shape. Still need to add a compartment for 4 AA NiMH batteries. 

So far the Teensy 3.2 works but I plan on switching to the Dragonfly (https://www.tindie.com/products/TleraCorp/dragonfly-stm32l47696-development-board/) for the ultra low power modes and built in 16mb flash storage.  

Just pulled the trigger on a v1.1 board order. Notable changes:

• Thicker solder through holes for the Teensy
• Proto-holes underneath the Teensy breakout. Each pad is connected to at least one extra hole. VIN, GND and 3.3V are each connected to two extra pads.

Similar to the PocketCHIP "Mechanical" Keyboard I've designed a hinged key faceplate that can be used standalone or mounted in another project.

Here you can see the PCB mounted using small self tapping plastic screws.

The keys are held in place with straitened paperclips. Music wire would probably be a better alternative. You can see where the paperclips are inserted on the edge of the faceplate above.

Here is the front. Keys have inkjet printed avery labels on them, nothing fancy yet. Font for the legends is https://github.com/be5invis/Iosevka

So far so good. Everything works as expected but there are a few minor problems.

1. Typo on silkscreen label on the breakout header for A9/D23. Appears as A9/D32.
2. Through hole solder pads on the Teensy breakout are too thin.
3. Holes for the surface pads on the Teensy 3.2 are useless and not connected to anything. Should probably be replaced with some proto holes.