Damiao Motors and CAN Bus

This guide covers setup and usage of Damiao motors with LeRobot via CAN bus communication.

Currently, only Linux is supported, as the OpenArms CAN adapter only has drivers for Linux.

Linux CAN Setup

Before using Damiao motors, you need to set up the CAN interface on your Linux system.

Install CAN Utilities

bash

sudo apt-get install can-utils

Configure CAN Interface (Manual)

For standard CAN FD (recommended for OpenArms):

bash

sudo ip link set can0 down
sudo ip link set can0 type can bitrate 1000000 dbitrate 5000000 fd on
sudo ip link set can0 up

For standard CAN (without FD):

bash

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

Configure CAN Interface (Using LeRobot)

LeRobot provides a utility script to setup and test CAN interfaces:

bash

# Setup multiple interfaces (e.g., OpenArms Followers with 2 CAN buses)
lerobot-setup-can --mode=setup --interfaces=can0,can1

Debugging CAN Communication

Use the built-in debug tools to test motor communication:

bash

# Test motors on all interfaces
lerobot-setup-can --mode=test --interfaces=can0,can1

# Run speed/latency test
lerobot-setup-can --mode=speed --interfaces=can0

The test mode will scan for motors (IDs 0x01-0x08) and report which ones respond. Example output:

can0: UP (CAN FD)
  Motor 0x01 (joint_1): ✓ FOUND
    → Response 0x11 [FD]: 00112233...
  Motor 0x02 (joint_2): ✓ FOUND
  Motor 0x03 (joint_3): ✗ No response
  ...
  Summary: 2/8 motors found

Usage

Basic Setup

python

from lerobot.motors import Motor
from lerobot.motors.damiao import DamiaoMotorsBus

# Define your motors with send/receive CAN IDs
motors = {
    "joint_1": Motor(id=0x01, motor_type_str="dm8009", recv_id=0x11),
    "joint_2": Motor(id=0x02, motor_type_str="dm4340", recv_id=0x12),
    "joint_3": Motor(id=0x03, motor_type_str="dm4310", recv_id=0x13),
}

# Create the bus
bus = DamiaoMotorsBus(
    port="can0",  # Linux socketcan interface
    motors=motors,
)

# Connect
bus.connect()

Reading Motor States

python

# Read single motor position (degrees)
position = bus.read("Present_Position", "joint_1")

# Read from multiple motors
positions = bus.sync_read("Present_Position")  # All motors
positions = bus.sync_read("Present_Position", ["joint_1", "joint_2"])

# Read all states at once (position, velocity, torque)
states = bus.sync_read_all_states()
# Returns: {'joint_1': {'position': 45.2, 'velocity': 1.3, 'torque': 0.5}, ...}

Writing Motor Commands

python

# Enable torque
bus.enable_torque()

# Set goal position (degrees)
bus.write("Goal_Position", "joint_1", 45.0)

# Set positions for multiple motors
bus.sync_write("Goal_Position", {
    "joint_1": 45.0,
    "joint_2": -30.0,
    "joint_3": 90.0,
})

# Disable torque
bus.disable_torque()

Configuration Options

Parameter	Default	Description
`port`	-	CAN interface (`can0`) or serial port (`/dev/cu.usbmodem*`)
`use_can_fd`	`True`	Enable CAN FD for higher data rates
`bitrate`	`1000000`	Nominal bitrate (1 Mbps)
`data_bitrate`	`5000000`	CAN FD data bitrate (5 Mbps)

Motor Configuration

Each motor requires:

id: CAN ID for sending commands
motor_type: One of the supported motor types (e.g., "dm8009", "dm4340")
recv_id: CAN ID for receiving responses

OpenArms default IDs follow the pattern: send ID 0x0N, receive ID 0x1N where N is the joint number.

Troubleshooting

No Response from Motors

Check power
Verify CAN wiring: Check CAN-H, CAN-L, and GND connections
Check motor IDs: Use Damiao Debugging Tools to verify/configure IDs
Test CAN interface: Run candump can0 to see if messages are being received
Run diagnostics: lerobot-setup-can --mode=test --interfaces=can0

Motor Timeout Parameter

If motors were configured with timeout=0, they won't respond to commands. Use Damiao Debugging Tools to set a non-zero timeout value.

Verify CAN FD Status

bash

ip -d link show can0 | grep fd