Ok, so I ended up getting the new calculator in the mail as well as some as the Raspberry Pi 3 B+ yesterday. However, I had a delayed package as well as a couple that were delivered to the apartment office right before it closed, so I had to wait until they opened today to pick them up. So now I also have a circuit board holder, a replacement magnifying glass (like the one I used to examine the circuit board traces), the MCP3008, and a raspberry pi cobbler. I ended up giving my Raspberry Pi 2 to my son because he was excited to get his hands on a Raspberry Pi. Also, I wasn't sure if I would need a power switch, so I got one of those in one of my orders. However, it's looking like it won't be necessary.

I took apart the new calculator and enlarged the window for the LCD using a combination of a Dremel tool, an X-Acto knife, and a file and it turned out pretty good. I hot-glued the LCD in place, kept the keys from my previous TI-83 and started carving up the insides of the calculator for the external ports. I also cut a sheet of Kapton tape to the size of the circuit board that I had from my 3D printer supplies so that I could set boards right on top of the existing board. I wanted to free up an SD Card for my son, so I ended up putting a 16GB card inside the calculator and setting it up just to make sure my process was easily duplicatable. I still need to set up bluetooth again, but I know I can do it for sure now.

I'm considering building a second calculator after my first because a lot of the research and software writing will be done with my first one, so it will be much easier. Besides, I already have much of the stuff needed to set up a second one. I would need a couple of displays, a PowerBoost 1000C, another battery, an HDMI extender, and another USB port (unless I just use that extra one I have). I guess I didn't realize how much stuff I actually needed, but I'll have to think about it.

Since I don't want to solder a header onto my Raspberry Pi Zero, I went ahead and attached the cobbler to the Raspberry Pi 3 and hooked that into a breadboard. I put a little solder on each of the keypad wires and attached them into the breadboard. I went and wrote a good chunk of a device tree overlay file and compiled it, but unfortunately it didn't actually function on my first attempt. I unhooked it and manually tested every key with a multimeter and it tested fine, so I'm not quite sure of the issue yet. Most likely it's something in the device tree file that's backwards or missing. I noticed some artifacts on boot up if I have the keypad connected. Tomorrow, I'll get a T-cobbler and then I won't need to route the wires around the ribbon cable, so that will be nice. Also, as a test, I hooked up the On button and wrote a script to shut it off if I hold the button for 2 seconds and that works beautifully.