It sounds quite awesome actually. Something you may want to think of is Keoni's soundchip. If it is possible to have it running on the Arduino and speakers then it's going to be epic.

iirc the inside of the calculator is already regulated at 3.3v, so you won't need an extra regulator for the arduino. You might need a new voltage regulator for the lithium battery though, because I don't think the default regulator will work well with a 3.7v battery.

BTW: Will you be able to use the arduino to run costom code, as a 2nd CPU? Or is it basically a calcnet/sound card?

Thanks for the feedback! i plan on making sure the arduino is reporgramable so technically you could make it do what ever you want but for the first couple attempts on this it will be specific functions only.

@soundchip  depends on how much room we have to spare we have very limited space and i have to include a few user accesable buttons/switches still.

Looking into the battery part of things again i originally intended to use a buckboost charger/converter for the arduino and calculator power. my only fear is a lower capacity battery will run out quickly depending on whats going on.

I have a lot of features i want to include with the sdcard and i will be putting it into teh schematic soon as time allows. mostly i want it to remove the need for a link cable and with a custom application be able to browse the sd card and interface with it and send programs using the standard ti link protocol instead of a custom one. so that multipage apps and the works actually can be sent. for extra storage space and all that. I also plan on making stuff exportable to the card but that's last on the list as if its not completed its not the end of the world its still a feasible mod!


@ben_G the arduino will be running off a converter and not the calculators internal for a couple reasons mostly having todo with being able to reset it with out mucking up anything but the arduino.


*searches the tp4056

also anyone have a good source of LiPo/Li-Ion batteries let me know ive had trouble speccing them in the past.

also if this works and is easy enough to assemble I plan on making it available/offering install services because why the hell not!

Thanks art its been fun the entire time ive had it in my head ive gone through 4 or 5 feature revisions. I've talked with KermM about the feasibility of a lot of it and its been worked down to what I feel is the most bang for the $ and the middle range of hard to implement. This is also my first adventure into SMC soldering and product installation. So hopefully it goes as plan! will be awesome if it does. And as long as I have support, Motivation, and people helping me on stuff I don't know it should work out!!!!

we could work on that if you would like ^^ I really just need the arduino to work as a control board to change the settings on various lines to control if the speakers are attached or if the lights are on ect. everything after that is an addon.

I plan on making an application that will interface with the arduino to control all the settings.  The over clock portions will be an os mod tho and not me this mod specific.  We are just going to abuse the link protocol and have the arduino speak the ti link protocol and be able to configure everything that way

It's planned to be totally modular the reason I'm going for the light rod is I have personally tried a few back lighting methods they all sucked I mean I have a few more to try first but a form of light rod is indeed the best solution I have found.

As for help finding parts and support are really all I need right now. I can do most of this on my own long as I stay motivated so keep up the good work