$ show lodefmode/moviecart
This repository is a full-stack hardware and firmware project that enables a stock Atari 2600 console to play full-length color movies with audio from a custom cartridge containing a microSD card. The system consists of three major subsystems: (1) firmware for a Microchip dsPIC33CK64MC105 digital signal controller that reads movie data from FAT32-formatted SD cards and emulates the Atari 2600 cartridge bus interface in real time, (2) a 6502 assembly display kernel that generates the video signal using the TIA chip's playfield and color registers, and (3) a PC-based encoder implemented as a TouchDesigner C++ plugin (ColorizeTOP) that converts standard video files into the constrained .mvc format (80x192 resolution, 7-bit color, 4-bit audio). The firmware includes a bootloader with a custom update protocol, a Petit FatFs port for file access, and an interrupt-driven Atari bus emulator using computed-goto dispatch. The encoder performs cell-based quantization, kd-tree nearest-color search, and configurable dithering (Floyd-Steinberg, Atkinson, JIN) to map video frames to the Atari 2600's limited palette. The project also includes Eagle PCB designs for three cartridge board variants, assembly utilities, and example .mvc files. The architecture is well-modularized with clear separation between bootloader, main firmware, display kernel, and encoding tools, though some code duplication exists (e.g., flash driver copied across projects).
The LLM identified 3 files worth highlighting for reuse:
A self-contained assembly flash driver for Microchip dsPIC33 DSCs, providing functions for unlocking/locking the NVM controller, erasing pages, and writing rows/words in both 16-bit and 24-bit modes. It is isolated (no internal module imports), uses the standard NVMKEY unlock sequence, and handles alignment and error checking via NVMCON status bits. It can be extracted and reused in any dsPIC33 project requiring flash self-programming, such as bootloaders or OTA updaters.
The core video encoder as a TouchDesigner C++ plugin. It contains a complete, self-contained kd-tree implementation for nearest-color lookup from a fixed palette, multiple error-diffusion dithering matrices (Floyd-Steinberg, Atkinson, JIN), cell-based downsampling, and configurable color search. The pattern is generic and could be extracted to any project requiring fast palette-based image conversion. The plugin also demonstrates a well-structured TouchDesigner TOP plugin scaffold with parameter management, info channels, and thread-safe execution.
The Atari 2600 display kernel written in 6502 assembly, optimized to strict cycle counts for generating 60Hz interlaced video. It uses a macro-based approach to emit left and right playfield graphics via TIA registers, with HMOVE fine positioning and VDELP1 deferred updates. The code is page-aligned for timing accuracy and conditioned for NTSC/PAL variations. The pattern of cycle-exact kernel construction is reusable for any classic console homebrew development, and the macro structure allows independent extraction and adaptation.