Nlink lite

nternet-Link

An open-hardware platform that turns a TI-Nspire graphing calculator into a networked handheld terminal. It adds Wi-Fi, an AI chat/tutor, a camera that reads and solves problems, and onboard storage, all through a small plug-in device.

New to the Nspire scene? The spelling "nternet" is intentional. The Nspire's name plays on "inspire", and community projects follow suit by dropping the first letter, like the Ndless jailbreak playing on "endless". nternet is "internet", Nspire style.

Over four generations the project grew from a soldered-in modification into a clean, reproducible, plug-in platform with a proper communication protocol and custom PCBs.

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Not affiliated with or endorsed by Texas Instruments. This is an embedded-systems and networking experiment. It is not designed or intended for use during exams. Follow your institution's rules.

Try the calculator interface in your browser

The V4 calculator UI runs as a live simulator. The on-screen calculator and a virtual ESP32 talk over the real V4 wire protocol, so you can experiment with the whole experience before building anything.

Open the live simulator, or download v4/tools/gui_simulator.html and open it in any browser (it runs fully offline).

Which version should I look at?

Build V4. It is the current, recommended generation. The others are here as history and reference.

How it works

 TI-Nspire  =USB=>  nternet-Link device  =Wi-Fi=>  AI provider
 (keyboard,         (ESP32 + USB bridge             (Groq / OpenAI /
  screen, Lua)       + camera + SD)                  OpenRouter / local)

The calculator supplies the keyboard and screen and runs a Lua app. The device is an ESP32 that bridges USB-serial to Wi-Fi, calls an AI API, drives a camera, and stores photos and chat logs on a microSD card. In V4 the two sides speak nlink v1, a framed protocol with CRC checks and automatic retries.

Repository layout

README.md          you are here: the project hub
docs/              shared assets (hub images)
v1/                Ti-GPT, internal mod (legacy)
   firmware/       ESP32 .ino
   calculator/     Lua app + .tns
v2/                external adapter (docs)
v3/                ESP32-S3 and camera platform
   firmware/       ESP32 .ino
   calculator/     Lua app + .tns
   server/         host proxy server
v4/                CURRENT: the full rewrite
   README.md       tutorial and build guide (start here)
   src/ include/   ESP32 firmware (C++)
   calculator/     TI-Nspire Lua client + demo
   tools/          browser GUI simulator
   docs/           protocol spec
   test/           host-side tests
   hardware/       PCB design + 4 KiCad board variants

Each version folder has its own README. New here? Open v4/.

The story

V1 (2025) proved the concept by soldering an ESP32 onto the calculator's USB lines. V2 moved all the electronics outside into a plug-in adapter, with no calculator modification. V3 jumped to the ESP32-S3 with a camera and a host proxy. V4 is the ground-up rewrite: a reliable checksummed protocol, no API keys in the source (they live in the device's flash), support for any OpenAI-compatible AI provider, a browser simulator, automated tests, and two custom circuit boards.

Support

nternet-Link is a small side project, built in spare time and shared for free. If it's been useful to you and you'd like to chip in, tips go toward parts and the first run of ready made cables. No pressure at all, and thank you either way.

License and spirit

Open hardware and software. Modify, improve, and share. Built for learning about USB, serial protocols, embedded networking, and hardware interfacing.