Chibi-ECEN-BLDC - Three-Phase Brushless DC Motor Driver

A prototype BLDC motor controller designed for learning Mentor Graphics XDX PCB design (Fall 2014)

Overview

Chibi-ECEN-BLDC is a three-phase brushless DC motor driver PCB intended as a test platform for developing field-oriented control (FOC) software for a 480-watt brushless DC motor.

The design was inspired by Benjamin Vedder's open-source BLDC controller (VESC, v4, circa 2014), with customizations for this specific use case and a completely redesigned physical layout.

⚠️ Educational Prototype - This was a graduate student project from 2014 focused on PCB layout techniques for power electronics. While the design is complete and boards were fabricated, this should be considered a learning exercise rather than a production-ready design. Firmware development was not released as part of the project.

Key Features

• Three-phase BLDC motor control with field-oriented control capability
• Integrated DRV8302 driver with 5V buck converter and current sensing
• Multiple interface options: USB, JTAG, I2C, RS-232
• Hall effect sensor inputs for rotor position feedback
• Configurable throttle, brake, and torque sensor inputs
• Reverse polarity and over-voltage protection
• Thermal monitoring (motor and driver temperature)
• Heatsink mounting for D2PAK power MOSFETs
• RGB status LED and configuration DIP switches

Technical Specification

• Input Voltage: 48 VDC (nominal)
• Output Current: 10 Amps maximum (bus input average)
• Switching Frequency: 20 kHz
• Microcontroller: STM32F405RGT6 (ARM Cortex-M4, 168 MHz)
• Driver IC: DRV8302 three-phase bridge pre-driver with integrated buck converter
• PCB: 4-layer design optimized for thermal management and high-current routing

Key Design Challenges

The primary focus of this project was layout for a high-current system and managing a large component count. Design constraints included:

• Thermal Management - Large copper pours for power routing, heatsink mounting clearances
• High Voltage Isolation - 0.006" trace separation for 50 VDC systems (per IPC standards)
• Power Handling - Appropriate trace widths for 10A current capacity
• EMI Mitigation - Separation of digital, analog, and power domains

Layout techniques explored include push-and-plow routing, teardrop vias, and conductive copper shapes for optimizing power pad connections.

Design Tools

• PCB Design: Mentor Graphics Xpedition XDX (EEVX.1, 2014)
• Schematic: Xpedition
• MCU Configuration: STM32CubeMX
• Simulation: LTspice

Repository Contents

├── README.md                    # This file
├── LICENSE                      # MIT License
├── hardware/
│   ├── schematic.pdf           # 5-sheet schematic
│   ├── bom.csv                 # Bill of materials (CSV format)
│   └── bom.ods                 # Bill of materials (OpenDocument)
├── gerbers/                    # Manufacturing files (Gerber + drill)
│   ├── Gerber/                 # Gerber plot files
│   └── NCDrill/                # NC drill files
├── design-source/
│   ├── xdx/                    # Mentor Graphics Xpedition source files
│   ├── cubemx/                 # STM32CubeMX configuration
│   └── simulation/             # LTspice simulation files
├── docs/
│   ├── hardware-specification.md   # Detailed system specifications
│   ├── pinouts.md                  # STM32 pin assignments
│   └── connectors.md               # Connector pinout reference
├── datasheets/                 # Key component datasheets
└── media/                      # Board photographs
    ├── chibi-ecen-bldc-front-transparent.png
    └── chibi-ecen-bldc-back-transparent.png

Getting Started

Manufacturing (not recommended)

Gerber files and drill files are available in gerbers/. The PCB is a 4-layer design:

• Layer 1: Top copper (signal + power)
• Layer 2: Inner ground plane
• Layer 3: Inner power plane
• Layer 4: Bottom copper (signal + power)

Documentation

• Hardware Specification - Detailed system design
• Pin Assignments - STM32 pinout reference
• Connector Pinouts - External connector reference

Bill of Materials

The complete BOM is available in hardware/bom.csv and hardware/bom.ods. Key components:

• STM32F405RGT6 microcontroller
• DRV8302 motor driver IC
• Power MOSFETs and Schottky diodes (D2PAK)
• Supporting passives and connectors

Note: The Xpedition source files are in a legacy format. The PDF schematic in hardware/ is recommended for viewing.

License

This project is released under the MIT License - see the LICENSE file for details.

Copyright (c) 2014 Jone Lay

You are free to use, modify, and distribute this design for any purpose, with attribution.

Open Source Hardware

This project is open source hardware. The design files, manufacturing files, and documentation are freely available for educational and non-commercial use.

Disclaimer

*This project is shared for educational purposes and as a portfolio piece. It was a graduate student project from 2014. While care was taken in the design and the hardware was successfully manufactured and tested, this is not a production-ready design. Use at your own risk. Motor Control and 48V power systems must be designed with extreme care for safety - this design is presented for educational purposes only.