OmniRevolve

XY plotter (scalable to 15 colors) — STM32F446 with a deterministic 10 kHz control loop (TIM4 ISR) driving multi-axis step generation, endstop handling, homing/calibration, stream timing and an action FSM (tap, color change, pen up/down); ESP32 (FreeRTOS + micro-ROS over Wi‑Fi), ROS 2 UI, SPI DMA 512 B streaming, CRC protocol.

System Architecture

flowchart LR subgraph PC UI["ROS 2 UI (Tkinter)"] Agent["micro-ROS Agent (UDP)"] end subgraph ESP32 MROS["micro-ROS Node / FreeRTOS"] OLED1["OLED SSD1309"] end subgraph STM32 MCU["STM32F446 (NUCLEO-F446RE)"] TIM4["TIM4 @ 10 kHz - step generation"] OLED2["OLED SSD1309"] Endstops["Hall + mechanical endstops"] end subgraph Mechanics TB6600["TB6600 drivers"] NEMA["NEMA17 steppers (X/Y/pen conveyor/carousel)"] Head["Carousel + Z carriage + Pen conveyor"] end UI -- "/plotter/byte_stream + cmds" --> MROS MROS -- "SPI DMA: 512 B chunks" --> MCU MCU -- "UART status/CRC" --> MROS MROS -- "/plotter/telemetry" --> UI MCU --> TIM4 MCU --> Endstops MCU --> OLED2 MROS --> OLED1 MCU --> TB6600 --> NEMA NEMA --> Head

Highlights

Deterministic 10 kHz control loop (TIM4 ISR): multi-axis steps, endstops, homing/calibration, stream timing & action FSM (tap / color change / pen up-down).
Reliable SPI DMA streaming (512 B, double buffering) and CRC-based UART control/status.
ESP32 micro-ROS over Wi-Fi; ROS 2 UI with live preview and progress (bytes_processed).
STM32 firmware refactored C → C++ with clear module boundaries.