BLDC ECU (2 ch Motor Driver)

A STM32G473-based 2-channel BLDC motor driver ECU for an autonomous park-cleaning robot. Designed for ROS2 Nav2 integration via CAN. Self-designed PCB, schematics, and firmware. (Capstone Project)

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Features

• 2-Channel BLDC — Independent Hall-sensor-based 6-step commutation for M0 and M1
• Dual Control Mode — CAN mode (ROS2 speed command) / Manual mode (joystick or fixed RPM)
• CAN Interface — FDCAN1 at 500 kbps, ROS2 Nav2 compatible frame format
• Speed Control — Open-loop ramp with PI closed-loop option per motor
• Joystick Steering — 4-zone discrete differential steering (forward / turn left / turn right / stop)
• E-stop — Hardware brake via BKIN pin (fail-safe: fires on wire break)
• Protection — Overcurrent (10 ms trip), overheat (NTC), undervoltage, Hall fault

Status

Feature	Status
6-step Hall commutation	Done
Dual control mode (CAN / Manual)	Done
Joystick differential steering	Done
E-stop (BKIN fail-safe)	Done
Overcurrent / overheat / undervoltage protection	Done
ROS2 Nav2 integration	Done
PI closed-loop speed control	In progress
CAN communication (CANable)	In progress

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Repository Structure

BLDC_Motor_Driver/
├── FW/
│   └── F473VET6/
│       └── BLDC_FW_V0.0.1/
│           ├── Core/
│           │   ├── Inc/
│           │   │   ├── bldc_config.h
│           │   │   ├── bldc_motor.h
│           │   │   ├── bldc_hall.h
│           │   │   ├── bldc_adc.h
│           │   │   ├── bldc_can.h
│           │   │   ├── bldc_mgr.h
│           │   │   └── bldc_led.h
│           │   └── Src/
│           │       ├── bldc_motor.c
│           │       ├── bldc_hall.c
│           │       ├── bldc_adc.c
│           │       ├── bldc_can.c
│           │       ├── bldc_mgr.c
│           │       └── bldc_led.c
│           └── Drivers/
└── HW/
    ├── BLDC_DRIVER/
    └── BLDC_ECU/

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Bill of Materials (BOM)

ECU Board

Component	Model
MCU	STM32G473VET6
CAN Transceiver	SN65HVD230
Regulator	AMS1117-3.3
Crystal	X322516MLB4SI

Driver Board

Component	Model
Gate Driver	UCC27211D
NMOS	BSC014N06NS (60V / 100A)
Schmitt Trigger	SN74LVC3G17DCTR
Op-Amp	TLV2374IPWR
Shunt Resistor	PA2512FKE7T0R002E (2 mΩ)
NTC Thermistor	NTCS0603E3103FLT (10 kΩ)

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Hardware

PCB

Board	Size	Layers	Design Files
ECU	100 × 60 mm	4	HW/BLDC_ECU/
Driver	80 × 100 mm	4	HW/BLDC_DRIVER/

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Software

System Diagram

  ┌───────────┐       CAN 0x200 CMD       ┌──────────────────────────┐
  │  ROS2     │ ─────────────────────────►│                          │
  │  Nav2     │◄───────────────────────── │       STM32G473          │◄─── E-stop (BKIN)
  └───────────┘  CAN 0x210/0x211 STATUS   │                          │
                                          │  FDCAN1  │  Scheduler    │
  ┌───────────┐  JOY X/Y  (ADC5)          │  PI Ctrl │  20kHz ISR    │
  │ Joystick  │ ─────────────────────────►│  Commutation / Protect.  │
  │  (Debug)  │                           └────────┬──────────┬──────┘
  └───────────┘                             PWM M0 │          │ PWM M1
                                  ┌────────────────▼──┐  ┌───▼────────────┐
                                  │    Bridge  M0     │  │   Bridge  M1   │
                                  └────────┬──────────┘  └──────┬─────────┘
                                           │                    │
                                  ┌────────▼──────────┐  ┌──────▼─────────┐
                                  │    Motor  M0      │  │   Motor  M1    │
                                  │   (Left Wheel)    │  │ (Right Wheel)  │
                                  └────────┬──────────┘  └───────┬────────┘
                                           │  Hall / Current     │
                                           └──────────┬──────────┘
                                                      │
                                         Feedback to 20kHz ISR
                                        Hall: TIM3/TIM4  Current: ADC1~4

Architecture

Single-MCU, bare-metal with a HAL-tick software scheduler. No RTOS — the 20 kHz commutation ISR requires deterministic latency.

Task Period	Content
20 kHz ISR (TIM8 / TIM1)	Commutation, E-stop guard, stall kick, overcurrent, open-loop ramp
Hall ISR (TIM3 / TIM4)	RPM calculation, immediate commutation update
1 ms	Current sampling (ADC1~4), PI speed controller
10 ms	Bus voltage + NTC (ADC5), undervoltage / overheat protection, LEDs
100 ms	CAN status TX (0x210 / 0x211), RX watchdog

CAN Frame Format (500 kbps, Classic CAN)

RX — ROS2 → ECU

ID	DLC	Byte	Content
0x200 CMD_SPEED	8	B[0:1]	M0 RPM ref — int16 LE, LSB = 0.1 RPM
		B[2:3]	M1 RPM ref — int16 LE, LSB = 0.1 RPM
		B[4]	M0 direction (0=CCW / 1=CW)
		B[5]	M1 direction (0=CCW / 1=CW)
		B[6]	Enable flags (bit0=M0, bit1=M1)
0x201 CMD_CTRL	2	B[0]	bit0=M0 clear fault, bit1=M1 clear fault, bit2=M0 PI, bit3=M1 PI

TX — ECU → ROS2 (100 ms)

ID	DLC	Byte	Content
0x210 STATUS_M0	8	B[0:1]	Actual RPM — int16 LE, LSB = 0.1 RPM
0x211 STATUS_M1		B[2:3]	Max phase current — int16 LE, LSB = 0.01 A
		B[4]	Temperature — int8, LSB = 1 °C
		B[5]	Fault code (0=none, 1=OC, 2=overheat, 3=undervolt, 4=BKIN, 5=Hall)
		B[6]	Flags (bit0=enabled, bit1=PI, bit2=spinning)

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Build

Requirements: [STM32CubeIDE]

1. File → Import → Existing Projects into Workspace
2. Select: FW/F473VET6/BLDC_FW_V0.0.1
3. Build (Ctrl+B) → Flash via ST-Link

Key Config (bldc_config.h)

Macro	Default	Description
BLDC_VOLTAGE_PROFILE	36	System voltage: 12 or 36
BLDC_ACTIVE_MOTOR_COUNT	2	0=no HW / 1=M0 only / 2=M0+M1
BLDC_JOY_ENABLE	0	0=fixed RPM / 1=joystick steering
BLDC_NONCAN_FIXED_RPM	200.0	Manual mode fixed RPM
BLDC_HW_CURRENT_SENSING	1	Disable if shunt not connected
BLDC_HW_NTC	1	Disable if NTC not connected

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Copyright (c) 2026 Kim Yuhwan