sm2can 0.1.0

Open-source macOS/Linux driver for SM2 Pro (Scanmatik 2 Pro) J2534 CAN adapter

SM2CAN — Open-Source Driver for SM2 Pro CAN Adapters on macOS & Linux

SM2CAN is a userspace USB driver that enables SM2 Pro (and compatible) J2534 CAN adapters to work on macOS and Linux — platforms the manufacturer's driver does not support. It integrates with python-can, making it a drop-in replacement for any CAN interface.

Disclaimer: This project is not affiliated with, endorsed by, or sponsored by the manufacturer of the SM2 Pro hardware. All trademarks are property of their respective owners. This driver was developed using clean room reverse engineering of a legitimately purchased device for the sole purpose of interoperability. See LEGAL.md for full details.

Project Status

Component	Status	Notes
USB transport (libusb)	✅ Complete	Tested on macOS 13+ and Ubuntu 22.04+
USB hardware detection	✅ Complete	Auto-detects VID 0x20A2 PID 0x0001
Protocol decoder	🔧 Needs capture	Community USB captures welcome
Protocol auto-detection	✅ Scaffolded	Tries multiple frame format variants
python-can Bus interface	✅ Complete	interface='sm2' via entry point
CLI tools	✅ Complete	sm2can probe, monitor, send
USB capture analysis	✅ Complete	Parses pcap/pcapng from USBPcap
Homebrew formula	✅ Ready	brew tap aldoguzman97/sm2can
Linux udev rules	✅ Included	Non-root USB access
Bluetooth SPP transport	📋 Planned	Architecture ready for future support

How You Can Help

One USB capture from a Windows session completes this driver. If you can run Wireshark + USBPcap on Windows while connected to a vehicle:

pip install sm2can
sm2can-capture guide     # Step-by-step capture instructions
sm2can-capture decode mycapture.pcapng  # Auto-analyzes the protocol

See CONTRIBUTING.md for the 5-minute capture guide.

Installation

Homebrew (macOS)

brew tap aldoguzman97/sm2can
brew install sm2can

pip (macOS & Linux)

pip install sm2can

From source

git clone https://github.com/aldoguzman97/sm2can.git
cd sm2can
pip install -e ".[dev]"

Prerequisites

Platform	Command
macOS	brew install libusb
Debian/Ubuntu	sudo apt install libusb-1.0-0-dev
Fedora/RHEL	sudo dnf install libusb1-devel
Arch	sudo pacman -S libusb

Python 3.8 or later required.

Linux: USB Permissions

To use without sudo:

sudo cp scripts/99-sm2pro.rules /etc/udev/rules.d/
sudo udevadm control --reload-rules && sudo udevadm trigger
# Log out and back in (user must be in 'plugdev' group)

Quick Start

Detect hardware

sm2can probe

Monitor CAN bus

sm2can monitor --bitrate 500000

Send a CAN frame

sm2can send 0x7DF 0201000000000000 --bitrate 500000

Use with python-can

import can

# SM2CAN registers as a python-can interface plugin automatically
bus = can.Bus(interface='sm2', channel=0, bitrate=500000)

# Receive
msg = bus.recv(timeout=1.0)
if msg:
    print(f"0x{msg.arbitration_id:03X}: {msg.data.hex()}")

# Send
bus.send(can.Message(
    arbitration_id=0x7DF,
    data=bytes([0x02, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00]),
))

bus.shutdown()

Direct API

from sm2can import SM2Device

with SM2Device() as dev:
    dev.open(bitrate=500000)
    dev.send(0x7DF, bytes([0x02, 0x01, 0x00, 0, 0, 0, 0, 0]))
    frame = dev.recv(timeout=1.0)
    if frame:
        print(f"0x{frame.arbitration_id:03X}: {frame.data.hex()}")

Supported Hardware

Device	USB ID	Interface	Status
SM2 Pro (original)	20A2:0001	USB + BT	Primary target
SM2 Pro (clones)	20A2:0001	USB	Should work (same USB protocol)

Power Requirements

Important: The SM2 Pro requires 12V on the OBD-II connector to boot its application firmware. On USB 5V power alone, the microcontroller enumerates on the bus but the CAN transceiver and command handler do not start. Connect to a vehicle with ignition ON, or supply 12V externally.

OBD-II bench power pinout:

Pin	Function
16	+12V (battery)
4	Chassis ground
5	Signal ground

A 12V / 1A wall adapter wired to these pins is sufficient.

Architecture

┌──────────────────────────────────────────────────────────┐
│  Your Application / python-can / opendbc / UDS client    │
├──────────────────────────────────────────────────────────┤
│  SM2Bus (can_interface.py)                               │
│  python-can BusABC — registered via entry point          │
├──────────────────────────────────────────────────────────┤
│  SM2Device (device.py)                                   │
│  High-level: open / close / send / recv / background RX  │
├──────────────────────────────────────────────────────────┤
│  ProtocolCodec (protocol.py)                             │
│  Encode / decode binary protocol frames                  │
├────────────────────┬─────────────────────────────────────┤
│  USBTransport      │  BluetoothTransport (planned)       │
│  (usb_transport.py)│  (bluetooth_transport.py)           │
│  Bulk EP via libusb│  SPP via platform-native APIs       │
├────────────────────┴─────────────────────────────────────┤
│  Hardware: EP 0x02 OUT / EP 0x81 IN / 64-byte packets   │
└──────────────────────────────────────────────────────────┘

Why userspace instead of a kernel driver? A kernel extension (kext on macOS, .ko on Linux) requires code signing, kernel version compatibility, and administrator installation. A userspace driver via libusb installs with pip, works everywhere, and cannot crash your kernel. The SM2 Pro's simple 2-endpoint bulk design is ideal for this approach.

Roadmap

• USB transport layer
• Protocol codec with auto-detection framework
• python-can Bus interface
• CLI tools (probe, monitor, send)
• USB capture decoder for protocol analysis
• Homebrew formula
• Linux udev rules
• Complete protocol specification (pending community captures)
• Bluetooth SPP transport
• CAN-FD support (if hardware supports it)
• ISO-TP (ISO 15765) pass-through
• SAE J2534 API shim layer

Contributing

See CONTRIBUTING.md. The most impactful contribution is a USB capture from Windows — one file completes the protocol specification for everyone.

Legal

This project uses clean room reverse engineering to achieve interoperability with legitimately purchased hardware. No proprietary code, firmware, or documentation was used. See LEGAL.md for full details including applicable case law.

License

MIT — see LICENSE.

Copyright (c) 2026 Aldo Guzman (@aldoguzman97)

Acknowledgments

• pyusb — Cross-platform USB access
• python-can — CAN bus abstraction
• libusb — Userspace USB I/O
• Everyone who contributes USB captures