Live video on a TI-Nspire

The idea Video on a graphing calculator.

An ESP32-CAM takes pictures, turns them into pixel art with a limited palette, compresses them and sends them over serial. A Lua program on the TI-Nspire CX catches the stream and draws it.

The calculator also runs the UI, the controls and a chat that talks to a Discord channel.

The pipeline Every frame, on the ESP32.

capture frame        RGB565
  -> RGB888           colour space conversion
  -> 36 colours        weighted quantisation
  -> colour match + RLE
  -> Huffman           compression with little data loss
  -> Base64            safe for the serial line
  -> calculator        decode, draw, repeat

Two programs

cam.ino (ESP32-CAM)

Captures frames and turns them into a compressed feed of pixel art.

readport3.0 (TI-Nspire)

Receives and renders the feed, and handles the UI, controls and chats.

What is next

• Done: real time interface with a Discord channel
• Faster transmission
• A 3.3 V to 5 V booster or a Li battery instead of the 5 V supply
• Use the dock connector and hide the electronics

Wiring