Hello,

I am a new member to this forum having browsed as a guest for several weeks.

I have developed an interest in graphing calculators recently and am interested in having a go at creating one from a Raspberry Pi.

I was trawling the web in search of others who had done this, when I came upon this:

https://www.youtube.com/watch?v=lJu1ij_Emlk

I was particularly excited about this, as it was similar to what I had in mind: A powerful, do it all calculator, in a nice neat 3D printed case. I would be able to spend a little more time making it neater and fitting proper buttons though, as this seems more like a prototype.

I don't like the idea of using the Linux command line as the only interface, so I did some research and found that Raspberry Pis have access to free version of Mathematica. This would require a full qwerty keyboard (and mouse?) to be effective though, so I was wondering if anyone had any thoughts about operating systems (maybe just an emulator of an existing calc?) for the calc.

I am planning to use a resistive touchscreen, not entirely sure of dimensions yet.

Other then that, I haven't really thought about components so suggestions are welcome!

One thing to note is that I was hoping to spend less then $100 (excluding the Raspberry Pi).

I have limited experience with Raspberry Pis, so any input would be greatly appreciated.

Thanks in advance!

Hmm, for Mathematica to fit inside such a small calculator you will definitely need a high-density LCD.

I recommend using hardware keys instead of softkeys; it's extremely easy to tap the wrong thing when you can't feel what you're pressing. You might also want to keep the hardware keys as a separate module from the actual core board - this way, you could have different key layouts based on what type of calculator you want to emulate. The keys can use a limited set of GPIO pins.

But an open-source physical calculator is something we are very lacking, especially one that is user-friendly, doesn't rely on full QWERTY keyboard, and is up-to-date with all the branches of math that exist (like Mathematica).

You will be spending more than $100 on this project. Remember that prototyping is significantly more expensive than mass production. Do make sure you know what you are doing before you start this project, because it'll take a lot longer than you expect and it'll get your hands dirty...

Oh, nice. Good luck

I was once working on a Raspberry Pi inside a TI84+. A project I might restart soon.
However, currently I am working on a custom calculator that I might make into a community calculator t some point if it turn out to be usable (with custom keypad and a larger screen).

http://bmuessig.eu/posts/rpn-calculator-build-part-2

I'm curious, how does one input any operators with just a simple 12-button keypad?

As you might have already guessed from the project name, I am using reverse polish notation for input because I like that one a lot more. This means you enter tokens and not formula strings. I was thinking that you can enter a number at any time by entering the digits, and you can perform operations from the # menu. To make the calculation you could double tap the # key. I am not fully sure yet, how I want to make the UI but I will keep you updated

Yeah.. I had a hunt around and found a 320 x 480, 3.5", resistive touch screen for $40 that looks more then adequate.

https://www.adafruit.com/products/2050

I agree in regards to the hardware keys, but I was envisioning using the touch screen only because it seems that it would open up a huge number of possibilities, given that it is basically the same price as a non touch.

Using a separate module for the keyboard sounds sensible as well.

I was wondering about Mathematica though, as from my limited experience it seems like it would need a qwerty keyboard to be effective.

And I guess the budget will have to expand then

Thanks for your reply.



Thanks!

I would be interested to see the pi 84+..

Somebody offered me a calculator which is so awesome. That means it will be done
Btw don't go for the adafruit display. It's not worth it. I recommend getting the same display from another manufacturer.

While we're on the topic, I have a long-suffering "TI-87" project, using an Odroid board (roughly equivalent to a Raspberry Pi Zero, but produced two years earlier), inside a TI-83 Plus Silver Edition case. I'm aiming to use jsTIfied to emulate any of the calculators it can emulate, and the calculator's actual keypad with a color screen.

That sounds interesting.

How far through it are you and do you have any pictures?

I got stuck selecting an LCD, although I'd really like to get back to the project and get past the issue. The progress log is here on Cemetech, with pictures.

Why is that?

Wow.. surprised I didn't stumble upon that earlier!

That looks like a cool project!

What's the advantage of sticking with the Odroid board as opposed to a Pi Zero?

I believe that the Pi Zero wasn't out yet; hence an Odroid. I could be wrong, but that makes the most sense.

Also, please refrain from double posting unless you have a major project update, or it has been over a day since your post. You can use the edit button on the bottom right of your post if you find that you need to add more.

Has anyone ever completed any of the mentioned projects? I've seen the Pi Casio. Like some others I've been toying with the idea of running Mathematic or Wolfram Alpha Pro on my Raspberry Pi incased inside a shell a bit like a TI-92.

My calculator is essentially done.
All hardware is finished and the software does all it has to do. A few features are still planned though when I find time.