STM32 Motor Control Protocol (MCP)

Python implementation of ST Microelectronics' Motor Control Protocol for STM32-based motor controllers. This project provides tools and utilities for communicating with STM32 ESCs (Electronic Speed Controllers) via serial over the ASPEP (Asymmetric Serial Packet Exchange Protocol).

Status

Work in Progress - This project contains Python scripts for:

• ✅ Serial communication with STM32 motor controllers
• ✅ Motor start/stop commands
• ✅ Basic velocity control
• 🟡 Monitoring and data acquisition (partial)
• ❌ Full registry service (not implemented)
• ❌ Datalog service (not implemented)

Installation

From PyPI (Recommended)

pip install stm32-motor-control-protocol

Or with uv (faster):

uv add stm32-motor-control-protocol

From Source

git clone --recurse-submodules [email protected]:shanemmattner/stm32_motor_control_protocol.git
cd stm32_motor_control_protocol
uv sync

Quick Start

Hardware Requirements

• STM32G431-based ESC board
• BLDC motor with hall sensors or encoder
• 24V DC power supply
• USB serial connection

Basic Usage

from st_mcp.minimal_motor_control import MinimalMotorControl

# Connect to motor controller
controller = MinimalMotorControl(port="/dev/ttyACM0", baudrate=1843200)
controller.run()

This will:

1. Establish serial connection
2. Perform beacon handshake
3. Configure velocity mode
4. Turn motor on

Press Ctrl+C to stop and exit safely.

Project Structure

.
├── st_mcp/
│   ├── minimal_motor_control.py      # Working example script
│   └── commands/
│       ├── motor.py                  # Motor control commands
│       └── monitor.py                # Real-time monitoring
├── PROTOCOL_DOCUMENTATION.md         # Full project overview
├── MCP_PROTOCOL_NOTES.md            # Protocol specification
└── README.md                         # This file

Motor Commands

Start/Stop

from st_mcp.commands.motor import StartMotorCommand, StopMotorCommand

# Start motor
start_cmd = StartMotorCommand(motor_id=0)
response = mcp.send_bytes(start_cmd.to_bytes())

Control Modes

• Velocity Control: Speed-based motor operation
• Torque Control: Current-based motor operation

Real-Time Monitoring

from st_mcp.commands.monitor import GetMonitor1Command, Monitor1Data

# Get motor data
monitor_cmd = GetMonitor1Command()
response = mcp.send_bytes(monitor_cmd.to_bytes())
data = monitor_cmd.parse_response(response)

print(f"Speed: {data.speed} RPM")
print(f"Torque: {data.torque} Nm")
print(f"Temperature: {data.temperature}°C")

Available monitoring data:

• Monitor1: Speed, torque, flux, bus voltage, temperature
• Monitor2: Phase currents (Ia, Ib), D-Q currents, alpha-beta currents

Serial Communication

All commands are sent over serial at 1,843,200 baud using the ASPEP protocol:

Packet Structure

[Header: 4 bytes] [Payload: N bytes]

Connection Sequence

1. Send beacon: 55 FF FF 77
2. Receive beacon response
3. Echo response back
4. Receive confirmation
5. Send connection request: 06 00 00 60

Protocol Details

Motor Control Protocol (MCP)

• 4 core services: Command, Registry, Datalog, Notification
• Currently implements: Command Service only
• Registry and Datalog services available in firmware but not yet exposed via Python

ASPEP (Asymmetric Serial Packet Exchange Protocol)

• Point-to-point serial protocol
• 3 communication channels: Synchronous, Asynchronous, Control
• Optional 16-bit CRC checksum
• Low-level transport for MCP

See MCP_PROTOCOL_NOTES.md for full specification.

Serial Traffic Logs

The original electronics repository contains recorded serial traffic from the Windows Motor Pilot application for reference:

• Basic connect/disconnect sequence
• Motor start with velocity control
• Motor stop with ramp-down

These are useful for protocol validation and reverse engineering.

Known Issues & Limitations

1. Registry Service: Commands for reading/writing motor parameters not exposed
2. Datalog Service: Real-time data logging configuration not implemented
3. Error Handling: Limited error recovery in connection sequence
4. Testing: No automated test suite (hardware-dependent)

Next Steps

1. Implement Registry Service commands
2. Implement Datalog Service with configurable sampling
3. Add comprehensive error handling
4. Create test harness with mock STM32 device
5. Add parameter tuning utilities

References

Official ST Motor Control Resources

• ST Motor Control SDK Community - Official MCSDK support and documentation
• ST Motor Workbench - Motor Control SDK tools and downloads

Project Documentation

• MCP_PROTOCOL_NOTES.md - Motor Control Protocol (MCP) specification
• PROTOCOL_DOCUMENTATION.md - ASPEP protocol and project architecture

License

See individual file headers for licensing information.