As my background in embedded devices and circuit design takes me all over the board in terms of what my next project will become; due to the rather high prices of the nicer calculators and closed source nature of their firmware I thought it would be nice to create a calculator that is developed by the users themselves. Of course I had to come here before starting the project and so, if anyone would like to post ideas for what they would like to see in such a calculator (ex: functionality, I/O ports and the like) that would certainly be great. As well if anyone would like to help develop firmware for it; that would also be of great help as I am more comfortable with circuits, though I do work with assembly and C rather often and am more than competent to tackle this.

To outline some ideas I had for the calculator:
▪E-Paper Display (because they are a nice, sunlight readable, and that battery life increase)
▪Custom I/O port either with a shielded connector, or more arduino like pin connectors (or both?!)
▪USB with a mass media storage and serial terminal connection; thus allowing easy transfer of files (I've done this before on another project, so completely feasible)
▪Choice of rechargeable AAs or Lithium battery pack (most likely will have to have a module to switch out between the different charging/power management circuits)
▪Wireless connectivity (wifi, bluetooth, though I personally like ZigBee more cause of that point-to-point connectivity; possibly could lead to a wireless calculator network?)
▪IR to piss people off (this is just a joke, I wouldn't dare go near IR again after the issues I've had in the past)

So yeah, have at it! I'm excited to see what you all have in mind.

Maybe a model where the calculator has a large keyboard too. Maybe the battery could be used to charge a phone or something. I think the ideas you have already covered are great for a calculator.

This alone makes it really awesome - I absolutely love this technology.


Again, yes. I assume this is an externally mounted USB port for the serial, so what connector will you use? Also, how will internal memory be handled? on-board, or perhaps an Internal SD Card reader?


A Bluetooth connection may be a bit much for a simple calculator, but shoot, go for it if you want. As for WiFi, There is always the Spark Core, or whatever it is called these days. I don't know much anything about ZigBee, so I'm going to go look that up right now...

The ZigBee is overpriced and not worth what you get out of it. A few nrf24l01 transceivers are much more cost effective and faster for wireless transmitting as an example

Anywho, good luck with this project! I look forward to seeing what you create Welcome to Cemetech!

Stop making these projects people! You're making me feel more and more like a scrub every day!

I'm kidding of course, this seems like an awesome project to do, ever since I got my CE I've been dreaming of ways to make a (similar) but better calculator!

I have a few questions
1) how big/ how heavy do you think your calculator will be? (This wouldn't be a deal-breaker for me but I'm just curious.)
2) when you say USB are you meaning type A (what most people use) or type C? (what the new MacBook has) or both?
3) I'm not familiar with what firmware is so will run Linux, or does firmware mean a custom OS?
4) what will you name your masterpiece?

A few suggestions.
1) make it compatible with the TI-84 family
2) I would suggest a Li-ion battery pack if you are shooting for thinness .
3) support most programming languages! (C, Python, etc...)
4) make it touch-screen.
5) I like the idea of a keyboard.
6) I also like prgmTrouble's idea of a camera/ mic

How about a camera and/or microphone? (a little too far?)

Whoah not expecting the mass amount of posts, though I guess it is what to expect on here! Alright, now to address questions.

▪USB stuff: I'm leaning on mini usb since it is a better connector in terms of structure, though it is technically depreciated which I don't know how much that matters. I was just looking at USB-C stuff, ST has a chip that does handle the connector, though USB 2.0 speeds are more likely. I haven't found something that could handle USB 3.0 speeds that isn't really expensive and keeping this cost effective is certainly a goal. In terms of storage, micro SD cards are what I had in mind, though having a bit of extra flash is not a horrible idea either. The nice part about the USB protocol, is that the same port could be used for both the multimedia and serial terminal, with the device switching between both protocols. Though I'm thinking having a physical switch to change between modes would be the easiest to implement. I like physical settings because there isn't much that can go wrong there and it involves less programming haha.

▪Radio connections: All of the radio stuff is up in the air, though and those three were the first to pop into my head. LoRA is also an interesting thing to look into, since the really long range. I just thought of the ZigBee protocol since the mesh networking is kinda cool. Also having a ready made module would be nice, since a lot of them already have FCC approved stuff. One less thing to worry about. Though it would still need approval if it were to be commercial. I guess keep it as a kit for now haha.

For the size, I'm not too sure but I would assume around the same size of a TI-84. That's a really rough estimate, though I won't know till the board is finished.

I just found a 4.2in e-paper display on Digikey, which would be pretty a awesome. Though it is ~$58 which is less awesome. I'm having a bit of trouble sourcing off the shelf parts for the display. Regardless, here is a link to that display for those of you who want to see.
http://www.digikey.com/product-detail/en/pervasive-displays/E2417ES053/E2417ES053-ND/6211106

Of course I wouldn't want to make the thing like a giant iron brick, and the smaller it is the cheaper it is, so I suppose we will see. Maybe I'll make the thing flip open like the gameboy SP haha that would certainly be a sight.

Actually if this thing is low power enough, it would be somewhat hysterical to use supercapacitors as the main power source since you could then theoretically charge the thing in a couple of seconds to minutes. Hm I'll have to look into the max power draw first of course.

In terms of OS... probably none/custom kernel. I'm partial to bare metal, and plus performance benefits of course. So anything that can be compiled would be able to run on it, though loading programs is not my favorite thing to do, although arm microcontrollers (as I'm leaning to for this project) can execute programs from RAM, so it might be feasible to load an .elf file. I'll have to play around with it in the future.

For a camera, while it would be kinda funny to have I just don't see the benefits. Possibly having an extension to connect to a camera as in external I/O stuff for one might be nice though I'm not terribly concerned with it.

Name? Oh boy I have no idea; I'm completely open to suggestions. Maybe something to do with some famous early computer scientists/mathematicians like ada lovelace, though it could be anything really.

Scratch that, I found a similarly sized display for a third of the cost. $21 with parallel connections? Yes

Also here is a datasheet: http://dl.btc.pl/kamami_wa/gde043a2_ds.pdf

I'd have named it after my favorite scientist, Nikolai Tesla, but Elon already took the name. (Dammit)
You could do Marconi (Worked with radios), Faraday (electromagnetic induction), or Edison (Duh)

Cool project! This sounds like a lot of work, but with enough dedication, it could be done. If it were up to me, I'd have it named after Mary Shelley

Frankenstein reference...should have seen that one coming

Ooh I do like Faraday (as a name for the calculator, and the guy), he is pretty a awesome so I may consider it.

And yes, quite an ambitious task though not as ambitious as things I've done prior. I'm rather insane, if this thread couldn't convey that already haha

Hmm, I have never ever worked with PCB design, but I would love to see for once a PCB design for this project. We can use an ARM Cortex M3 - it's the minimum required ARM processor that has a full 32-bit instruction set. We can also use Micro-USB or USB-C.

Hmm... sounds cool! The way I would approach this project is to probably use an underclocked Raspberry pi zero (possibly a Pi 3 but of course desolder the large ports such as the USB's, Ethernet) . although that might not be the greatest for power consumption you could probably use something like a cell-phone battery and one of Adafruit's powerboost boards. and as for cameras I've heard that they are not hard to set up with the RPi interface. So that's just how I would do it. Anyways good luck on the project!

oldmud0, I was thinking of a cortex M4F, since floating point would kinda be essential for calculations (at least large ones). Or if I end up finishing my own processor design soon, I might just use it on a CPLD instead of an arm chip haha. Might make things waay to complex at that point though, but it would be interesting; we could then change the processor on the fly.

While I find RPis to be nice for simple quick solutions, I'm more on the complete do it yourself track. Plus it would give too much overhead for calculations, and trying to get a keyboard hooked up would be a little on the painful side. While I could just go for a microcontroller and be done with it. Plus I've done a couple power supply/charging circuits before, so 4A charging or something would be nice to throw on it haha. And yes, those parts exist and are cheap as hell. Now to find a charger that supports that much current...

Yeah, I was thinking the M4 would also be a great option as well, but wasn't sure about the power consumption compared to the M3. You could compile stuff from the Pi and bring it over. Perhaps you could also take advantage of the DSP capabilities with GNU Radio...?

And don't forget the TRRS jack!

Where does one draw the line between calculator and computer? In a sense they are synonymous, but think about what your average joe would classify your creation as. If you truly want a calculator, I would steer away from wireless connectivity. That's where it starts to be more a computer than a calculator.

This is not intended to be a high school calculator, subject to the limitations of teachers and standardized exams. This is intended to be a calculator for college and professional use, and for portability and productivity. It is, for all intents and purposes, a computer in the form factor of a calculator.

One idea that I have, but will probably not see the light of day, is a modular key layout system (so you can have an HP/TI/Casio-style layout if you are emulating those calculators), including a generic button layout that uses an E-Ink display for each and every button, so that buttons and their behaviors can be customized by both users and programs.

Another idea: I would like a calculator that, when in radians, leaves it's answers in terms of pi.

While this idea seems very useful, it would be hard to implement without it becoming a smartphone-esque device, and you would sacrifice the tactile press of physical keys, which is basically the only reason I own a TI-84 Plus CE, as an emulator does the same work (and more!).

I think a grid of standard keys that can be reprogrammed and reinterpreted by the OS would be more feasible, although difficult to code.