grblHAL/core is an embedded firmware for real-time CNC motion control, derived from the original grbl 1.1f project. It interprets G-code (RS274/NGC) and executes motion planning with acceleration/jerk profiles, driving stepper motors via a hardware abstraction layer (HAL) that supports many 32-bit MCUs (ESP32, STM32, RP2040, i.MX RT, etc.). The architecture is modular: a plugin system allows adding spindles, I/O expanders, kinematics (CoreXY, delta, polar, wall plotter), networking, and custom M-codes. Key subsystems include a G-code parser, motion planner with look-ahead, stepper ISR with Bresenham and AMASS, state machine, settings registry with NVS persistence, virtual file system, and cooperative task scheduler. Communication streams (serial, TCP, WebSocket, Modbus) are multiplexed. The codebase is highly optimized for real-time constraints, uses extensive conditional compilation for configurability, and provides reusable patterns such as function-pointer-based HAL, callback chaining, and abstracted I/O. While some internal coupling exists, many modules (crc, regex, utf8, string utilities, PID, expression evaluator, task scheduler) are self-contained and extractable.
ESP3D is a feature-rich embedded firmware for ESP8266/ESP32 microcontrollers, designed to serve as a Wi-Fi/Ethernet bridge and full-featured controller for 3D printers, CNCs, and similar equipment. The firmware provides a modular architecture with support for multiple network protocols (HTTP, WebDAV, FTP, Telnet, WebSocket, Bluetooth), a web-based user interface, file system management (SD card, flash filesystems like LittleFS/SPIFFS), sensor integration (DHT, BMP280), Lua scripting, and graphical displays via LVGL or TFT_eSPI. It includes a comprehensive command system (ESPxxx commands) for configuration and control, with authentication levels and persistent settings. The codebase demonstrates solid engineering for an embedded Arduino project, with clear separation of concerns between core services (serial, network, display, filesystem) and a message-passing inter-module communication pattern. It bundles many well-known third-party libraries (LVGL 8.2.0, TFT_eSPI 2.5.43, SdFat 2.2.3, EspLuaEngine, arduinoWebSockets) directly in the repository, ensuring reproducible builds but also creating a maintenance burden. The firmware is actively maintained with a responsive issue tracker and regular commits, though the reliance on pinned library versions and heavy conditional compilation introduces some technical drift.