Skip to main content

Building a custom calculator: setting up the prototype

My objective for starting a new project is to build a completely custom calculator that fits within a currently existing Texas Instruments calculator so I can simply pass off my mini-computer as an officially recognized standardized testing compatible calculator. Since I need to make sure this is a feasible project, I need to first gather materials that I currently have accessible so I can build a working prototype before I begin making any adjustments. So what can I find around my room?

I have quite a few Raspberry Pis from my purchasing sprees in middle school, so that seems to include an original revision Raspberry Pi Model A+. Although the Raspberry Pi Zero W would be better suited for this application, as it is a smaller profile, is smaller, faster, and uses less power, for the purposes of a basic prototype this should work just fine.

The next thing I found was a second revision PiTFT 320x240 touchscreen LCD that I bought from Massdrop. It is the only thing I ever bought from Massdrop, and unable to initially get it to work, I concluded that I had bought a faulty product. Although it is too late to try to get a replacement years later, I decided I might give a try at trying to make it work one last time.

The last thing I found was an old TI-85 which has since been replaced by my TI-84 Plus CE calculator. Since I no longer have any use for this calculator and my sister will not be using it, I may as well take it apart should I choose to go through with the project and complete the task.

Per the documentation it is probably the best idea to use Etcher for installing the Raspbian operating system. I downloaded this image from March 2018 onto my computer and will be using it on a 16GB Class 6 SD card, essentially the bare minimum.

Flashing with Etcher proved to be quite simple, all was needed was a simple click and a selection of the drive, and the device was flashed. It is compatible with both zipped IMG files as well as IMG files themselves, which makes the process very easy and convenient. This worked well with an unbranded 16GB microSDHC card, which is more than likely simply a Chinese knockoff of some well known microSD card.

There’s just a few more things I need before I can get started. I’ll grab a wireless adapter, as well as a keyboard, an HDMI to VGA adapter, and a few other cables to set up the Raspberry Pi. Since the Model A+ only has one USB port, I’ll only be able to use one preipheral at a time so I’ll need to set up WiFi without the WiFi adapter connected.
I attempted to set up the Raspberry Pi, but at this stage I found a new project to work on, and because the new project is more interesting, I will be putting this project on hold for time being. I may revisit it in the future.