The first step for this project is to have a functioning USB Keyboard (which can be used separate or integrated with the palmtop directly. This is the part of the project that has the most unknowns to me so I'm tackling it first.
I already have a USB Keyboard PCB design based on the Blackberry Q10 keyboard, the teeny tiny "BM14B(0.8)-24DS-0.4V(53)" connector and an ATMEGA32A-PU (which will run the QMK Firmware). There is some excellent documentation on this Github project that I'm working off of. I would love to just have some of the boards manufactured and get on with the palmtop design, however there are still some unknowns (to me).
- How do I control the backlight LEDs? There are 4 pins on the connector for the LEDs but I haven't been able to find any information on how to control them.
- How can I use the MEMS Microphone that's built in to the keyboard? This isn't a must but it would be incredibly useful to be able to use that built in microphone.
- Does the keyboard have built in diodes to prevent key ghosting, or will I have to include those in my design?
- Are there any other Gotchas in interfacing the keyboard that I should know before finalizing the keyboard design?
So as a first exploratory step I've designed a breadboard friendly breakout board for the keyboard. (I got the idea from this project) I'm getting the boards produced by JLCPCB and if they work I plan to sell them at a local cost if anyone is interested - I'm kind of hoping this will help me finance the next steps of the project although that may just be a pipe dream.
Additionally I haven't really done much surface mount soldering work and this connector is way to small (for me) to consider hand soldering. With that said I have one of These cheap reflow plates from Aliexperess on order. I know it's not the best but it seems like a good place to get started.
Next up for the project: waiting. Waiting for the PCBs to be manufactured and delivered, waiting for the reflow plate to arrive, waiting for the connectors to arrive... it's all coming from China so the waiting is usually on the order of months - but it's cheap and that makes it easier to learn!