Sourcing the parts
After looking at belsamber’s blog more closely, I realized it was a lot more than just a cool story — he actually presented a really good summary of what he needed, and how he did everything. Not quite an itemized step-by-step tutorial by any means, but his blog definitely had all the necessary detail.
Plus he even had his Python-based keyboard driver script for his Model 100 keyboard in a blog entry as well. As you’ll see later, I had to modify it pretty extensively in order to support all the additional key mappings for generating things like both the left and right square brackets (braces), the DEL key, the number keys when the NUM-LOCK is selected, and various CODE-modified keys, including left and right curly braces and the F9-F12 function keys. Effectively it’s evolved into my own custom keyboard driver at this point.
I realized that I could get everything working on the bench first and not have to deal with cramming it all inside a Model 100 case initially. My setup would include:
PINE A64-LTS v2 Single Board Computer (SBC) with 2G RAM, which can run
256GB Ultra microSDXC - this will be the hard drive for the PINE computer itself
5V 2A Switching Power Supply with a 3.5mm OD & 1.35mm ID barrel connector
1920x480 IPS display hooked up via an HDMI to mini-HDMI cable
WiFi / Bluetooth module that plugs into a special set of connectors on the PINE A64
3M double sided mounting tape to mount the IPS LCD to the Model 100's case
Ribbon edge connector for the Tandy 102 keyboard’s cable with 1.25mm pitch.
HDMI to mini-HDMI 19.6” cable to connect the PINE A64-LTS to the 1920x480 IPS LCD display.
A four-cell battery holder with a set of four 18650 cells wired in parallel that actually will get charged by the Pine A64 board's own charging circuit
GPIO breakout expansion board and ribbon cable, to allow me an easy way to work out the wiring of my spare Tandy 102 keyboard to the PINE’s GPIO connector.
JST-PH 2.0mm pitch 3-pin connector to connect the 4-cell 18650 (3.7v) battery pack to the PINE
DPDT 2-position panel mount switch so I could manually control power for the IPS LCD. This is needed because even when you shutdown the PINE, the display would still receive battery-level voltage from the connected batteries through the GPIO signals I would use for powering the LCD, so a switch takes care of that.
Machine screw kit so I could attach the panel mount switch to the side of the case. (I used the M3 size.)
3.5mm x 1.35mm male barrel plug to attach to the PINE inside the machine.
3.5mm x 1.35mm female jack to bring out to the side of the case, for the external power adapter to attach to.
Novus plastic clean & shine kit, for treating the area where the silk screening was.
I already had connecting wire of various sizes as well as shrink tubing on hand that I would use in this project. I also already had Tenergy-branded button top 18650 cells that are the protected-type that would fit into that battery holder. You really have to make sure the holder you’re using is capable of holding the slightly extra-long button-top protected cells. Other 18650 cell holders can be slightly shorter because they’re intended for the flat-top non-protected 18650s, and that won’t work.
Also I decided I’d go with the same Armbian OS setup as belsamber did. It just seemed the simplest. But in my case, I wanted to use the full graphic desktop environment instead of just a couple of terminal windows. The cool thing is, there are several DE’s that can run on a 2GB single board computer without problems, and I chose Cinnamon which runs just as well on Armbian as it does on it’s native distribution, Mint.
