python-cybergear 0.1.2

Python driver for the Xiaomi CyberGear brushless motor over CAN bus

cybergear

My four Xiaomi CyberGear motors (photo © grrodre)

Python driver for the Xiaomi CyberGear brushless motor over CAN bus.

Built on top of python-can. Tested with SocketCAN; custom polling threads are used instead of BCM to support other python-can interfaces as well.

If you run into any issues, feel free to open an issue.

Full documentation: grrodre.github.io/cybergear

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Features

• Five control modes: operation (MIT-style), position, speed, current, and quick-move
• Auto-scan: discovers motors on the bus without needing to specify a CAN ID
• Async feedback: can.Notifier-based listener delivers MotorFeedback snapshots without blocking
• Background polling: portable parameter polling thread keeps properties up to date on any interface
• Event callbacks: subscribe to feedback, parameter updates, and fault state changes
• Context-manager API: guarantees clean resource release
• Fault detection: decodes and monitors over-temperature, over-current, undervoltage, and encoder faults

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Requirements

• Python 3.10+
• python-can ≥ 4.4.2
• A CAN interface supported by python-can (e.g. SocketCAN can0 at 1 Mbit/s)

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Quick start

Scan for motors on the bus:

uvx --from python-cybergear cybergear-scan

Launch the dashboard:

uvx --from python-cybergear[dashboard] cybergear-dashboard

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Installation

pip install python-cybergear

Or with uv:

uv add python-cybergear

To include the dashboard (requires Textual and Rich):

pip install python-cybergear[dashboard]
# or
uv add python-cybergear[dashboard]

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CLI tools

Scan

Discover motors on the bus without writing any code:

cybergear-scan
cybergear-scan --interface socketcan --channel can0 --bitrate 1000000

Output:

Scanning CAN bus (timeout=0.5s)...

Found 1 motor(s):

  CAN ID     MCU Identifier
  ---------- --------------------
  1          8c1a313130333104

Dashboard

Live TUI dashboard showing feedback, parameters, and quick motor controls (requires cybergear[dashboard]):

cybergear-dashboard
cybergear-dashboard --interface socketcan --channel can0 --bitrate 1000000 --can-id 1

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Quick start

from cybergear import CyberGearMotor

bus_cfg = {'interface': 'socketcan', 'channel': 'can0', 'bitrate': 1_000_000}

with CyberGearMotor(bus_config=bus_cfg) as motor:
    motor.run_mode = 'speed'
    motor.enable()
    motor.spd_ref = 5.0          # 5 rad/s

Pass can_id explicitly if you have multiple motors on the bus:

with CyberGearMotor(bus_config=bus_cfg, can_id=1) as motor:
    ...

You can also omit bus_config entirely and let python-can read from its configuration file (~/.can, can.ini, or environment variables):

# interface, channel, and bitrate are read from the python-can config file
with CyberGearMotor() as motor:
    ...

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Control modes

Operation mode (MIT-style)

Directly command torque, position, velocity, and PD gains in a single frame:

motor.motor_control(torque=0.0, position=1.57, velocity=0.0, kp=10.0, kd=0.5)

Position mode

motor.run_mode = 'position'
motor.enable()
motor.loc_ref = 3.14   # rad

Speed mode

motor.run_mode = 'speed'
motor.enable()
motor.spd_ref = 10.0   # rad/s

Current mode

motor.run_mode = 'current'
motor.enable()
motor.iq_ref = 1.0     # A

Quick-move

motor.quick_move(speed=5.0)   # rad/s
# ...
motor.quick_stop()

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Reading motor state

Feedback is updated asynchronously from incoming CAN frames. Read the latest snapshot via motor.feedback:

fb = motor.feedback
print(fb.position, fb.velocity, fb.torque, fb.temperature)
print(fb.faults.has_fault)

Individual parameters polled in the background are also available as properties:

print(motor.mech_pos)    # rad
print(motor.mech_vel)    # rad/s
print(motor.v_bus)       # V

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Event listeners

Feedback listener

Called on every feedback frame in the can.Notifier thread. Keep callbacks fast.

def on_feedback(fb):
    print(f'pos={fb.position:.3f} vel={fb.velocity:.3f}')

motor.add_feedback_listener(on_feedback)
motor.remove_feedback_listener(on_feedback)

Parameter listener

Called whenever a polled parameter read response arrives.

def on_param(name, value):
    print(f'{name} = {value}')

motor.add_parameter_listener(on_param)

Fault listener

Called on any fault state transition (fault appears or clears).

def on_fault(faults):
    if faults.has_fault:
        print('FAULT:', faults)

motor.add_fault_listener(on_fault)

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Bus scanning

Discover all motors on the bus without constructing a CyberGearMotor:

motors = CyberGearMotor.scan(bus_config=bus_cfg)
for can_id, device_id in motors:
    print(f'found motor can_id={can_id}  device_id={device_id.hex()}')

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Motor limits

Parameter	Min	Max
Position	−12.5 rad	+12.5 rad
Velocity	−30 rad/s	+30 rad/s
Torque	−12 Nm	+12 Nm
Kp	0	500
Kd	0	5

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API reference

CyberGearMotor

Method / Property	Description
enable()	Arm the motor (clears latched faults)
disable()	Disarm the motor gracefully
emergency_brake()	Cut torque immediately
motor_control(torque, position, velocity, kp, kd)	MIT-style operation mode frame
quick_move(speed) / quick_stop()	Simple velocity motion
reset_zero_position()	Set current position as zero
encoder_calibration(timeout=30.0)	Trigger encoder calibration; returns electrical offset (float)
run_mode	Get/set run mode ('operation', 'position', 'speed', 'current')
feedback	Latest MotorFeedback snapshot
scan(bus_config, ...)	Class method: scan bus for motors
start_polling(interval) / stop_polling()	Control background parameter polling
close()	Release CAN bus and all resources

MotorFeedback

Field	Unit	Range
position	rad	±12.5
velocity	rad/s	±30
torque	Nm	±12
temperature	°C	*
mode	int	0 Reset, 1 Cal, 2 Run
faults	FaultState	*

FaultState

Field	Description
has_fault	True if any fault is active
over_temperature	Motor over-temperature
over_current	Over-current protection
undervoltage	Supply undervoltage
hall_encoding_failure	Hall sensor fault
magnetic_encoding_failure	Magnetic encoder fault
calibrated	False if encoder not calibrated

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Development

git clone https://github.com/grrodre/cybergear.git
cd cybergear
uv sync --dev

Run tests (excluding hardware tests):

uv run pytest -m "not hardware"

Hardware tests require a physical motor connected via CAN:

uv run pytest -m hardware

Lint and format:

uv run ruff check src/ tests/
uv run ruff format src/ tests/
uv run ty check

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Hardware

My Xiaomi CyberGear motors connected to the CANable USB adapter over a shared CAN bus.

CAN USB adapter

CANable PRO — USB to CAN adapter

Used to connect the CAN bus to a PC via USB. Bring up the interface at 1 Mbit/s:

sudo ip link set can0 type can bitrate 1000000
sudo ip link set can0 up

Motor cable

AMASS XT30(2+2) Xiaomi female cable for CyberGear

Power + signal cable required to connect the CyberGear motor (XT30 connector, 18 AWG power wires, 24 AWG signal wires).

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Author

Gregorio Rodrigo - [e-mail]

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License

MIT, see LICENSE.