I'm exploring the feasibility of a calculator WiFi project using ESP32's, and I'd like to feature pack the WiFi module with anything and everything relevant to the TI-83/84 link/USB ports. I'm more interested right now in just developing capable hardware, and a basic software contribution and then leaving the rest of the future potential development open source. My main goal would be able to download programs directly from Cemetech and ticalc over WiFi instead of needing to link through a computer. I've started a schematic already and am referencing old designs like the Arduino gCalc Net Adapter, as well as benryves' TIWiFiModem project. I am also referencing TILP and Kerm's ArtICL libraries. I had a couple questions for those in the community more experienced with using the link ports for various uses. Circuit boards will be produced through like JLCPCB.

The 2.5mm jacks are cheap and I think 3 is appropriate for local networking between multiple calculators? Are there any uses for 4 or more? Maybe just being able to link multiple calculators through one module?

Another consideration, should each be connected 1. physically, 2. through an analog switch, or 3. purely digitally through the extra available GPIOs? I've considered adding a 3.5mm jack as a spare, or to be available for headphones or audio out for the few projects that support that.

Buzzers can also be placed on the PCB- to my understanding the audio projects just use square waves and buzzers should be suitable.

SD card port for saving downloaded TI programs to share or for local calculator backups?

Power the module via USB C?

The idea of direct transfer from the web to calc is very cool and having the sd be able to back up stuff from the calc would also be a new feature.

Here's a set of potential features I've had in mind while designing the schematic:

▪WiFi direct download to calculator
▪WiFi/Bluetooth/ESP-WIFI-MESH for wireless calc-calc bridge or wireless LAN or WAN (gCalcNet) multi-calc network

▪SD card for saving downloaded files
▪SD card for saving calculator state/programs/variables etc.
▪SD card for saving calculator backups
▪Potential for program version control

▪Direct TI Link or USB Calculator connection
▪Any TI Link type capabilities including sending keypresses, taking screenshots, etc
▪USB C power passthrough to USB Mini port to be able to charge the rechargeable calculators
▪Wired LAN with four 2.5mm connectors

▪Two onboard buzzers for R and L channel audio as implemented by mTunes or select games like Pyoro.

▪128x64 SSD1306 type screen module for UI
▪Screen could be used to preview/display screenshots or actively mirror the display if someone wanted to figure out how the Presentation Link sends packets over USB. Potential screen recording?

▪Potential standalone calculator simulation
▪OTA ESP32 update capability
▪USB C ESP32 programming capability

I don't expect to have enough time to implement most of these in software, but I aim to design the hardware in a way that would make as many future developments possible as I can.

Here's where the project is at so far.
Biggest question I still have is if there are any strong feelings about having a 3.5mm jack instead of just 2.5mm. Still working on any finishing touches and then a good final rereview of my design to make sure I'm not missing anything.

That's looking great! With six 2.5mm jacks on board, I think you can spare switching one to a 3.5mm jack, although it may be a slightly tight squeeze. Do you intend to put this in a case of some sort? I don't see any screw or mounting holes and associated keep-out areas. If you intend this for the monochrome calculators, as your description suggests, I would be very curious about seeing it arranged with a male 2.5mm plug, so that it could be mounted directly on top of the TI-84 Plus/TI-84 Plus Silver Edition, like the Orion module.

You're literally describing my exact thought process! The 3.5mm jacks are quite a bit bigger relatively, but if I organize some of the parts around I think that I might be able to trade one out. If I understand right, the only purpose would be for headphones or speakers, which should actually be supported quite well by the GPIO MUX of the ESP32 to pass through the signals with a better drive strength and without affecting the rest of the TI-Link bus.



I found a model of a TI-84 calculator that someone had done and I thought it would be interesting to scale it down and fit the board inside to make it look like a miniature calculator.



This is exactly what I had originally been planning. but it turns out a pcb mount 2.5mm male connector is not the most common part, and probably more expensive than just using the link cable if it exists. Otherwise I would have wanted to design it so that it just looked like an extension on the top of the monochrome calculators like the Orion looks, or how the TI-Nspire Navigator looks. Same thing with the USB mini male connector. so instead I settled for fitting the module into a mini calculator form.

I have already been working on a little extra feature to this board that could put an OLED module right where the screen would be in the mini calculator as well.

Another use case I thought of associated with being able to take screenshots, you could share them with your phone over Bluetooth for quick access and media sharing in other ways.