Design and Implementation of a High- Precision STM32-Based 2D CNC Plotter with Real-Time G-Code Control

Abstract: Low-cost CNC plotters are a common entry point for students exploring motion control, yet most of them rely on 8-bit Arduino boards and plain Cartesian gantries that struggle past modest feed rates. This paper presents a 2D CNC plotter built around a custom controller board that uses an STM32F411CE (“Blackpill”) as the real-time motion core and an ESP32 as a user-interface co-processor. The mechanical platform is a CoreXY belt arrangement on a 3030 aluminum-extrusion frame driven by NEMA 17 stepper motors and TMC2209 silent-step drivers configured over UART. An SG90 micro-servo raises and lowers the pen. The controller PCB also routes a dedicated PWM channel and power connector for a 15 W diode laser module, which is supported in firmware and reserved for a future engraving extension but is not integrated in the present prototype. Firmware written with the STM32 HAL parses G-code line by line, performs trapezoidal acceleration planning, and produces coordinated pulse trains through hardware timers and DMA. Across repeated tests the plotter held positional deviation within roughly ±0.1 mm over a 100 mm square and repeatability within a 0.12 mm radius, while the TMC2209 drivers kept the machine quiet enough for classroom use. The results suggest that a dual-MCU architecture paired with silent stepper drivers offers a practical path to upgrading hobby-grade CNC hardware without discarding the ease of use that draws students to Arduino in the first place.

Keywords: CoreXY kinematics, G-code interpreter, laser engraving, STM32 microcontroller, TMC2209 silent stepper driver.