ros2-cyphal-bridge

ROS 2 <-> Cyphal bridge with YAML-configured routing and transforms.

Install

pip install ros2-cyphal-bridge

Requirements

• ROS 2 installed and sourced (for rclpy).
• Python >= 3.9.
• Cyphal DSDL types available via CYPHAL_PATH (e.g., the public regulated data types).
• libpcap (needed for UDP transport on Linux, and included in the Docker image).

Usage

ros2-cyphal-bridge --config bridge.yaml

Config format

Example example_bridge.yaml:

version: 1
cyphal:
  node_id: 99
  node_name: "com.manufacturer.project.example_ros2_bridge"
  can_iface: "socketcan:slcan0"
  can_mtu: 8
cyphal_to_ros2:
  - rule: "uavcan.node.Heartbeat.1.0@42 -> /nodes/uptime:std_msgs/msg/UInt32"
    transform: "data=int(msg.uptime)"

  - rule: "2000:uavcan.si.unit.pressure.Scalar.1.0 -> /robot/sensors/pressure:sensor_msgs/msg/FluidPressure"
    transform: "fluid_pressure=float(msg.pascal);variance=0.0"

  - rule: "2003:uavcan.si.unit.temperature.Scalar.1.0 -> /robot/sensors/temperature:sensor_msgs/msg/Temperature"
    transform: "temperature=float(msg.kelvin - 273.15);variance=0.0"

  - rule: "2001:uavcan.primitive.scalar.Bit.1.0 -> /robot/sensors/limit_switch:std_msgs/msg/Bool"
    transform: "data=bool(msg.value)"

ros2_to_cyphal:
  - rule: "/setpoint:std_msgs/msg/Float32 -> 2002:uavcan.primitive.scalar.Real32.1.0"
    transform: "value=float(msg.data)"

Cyphal config

• node_id: Optional Cyphal node-ID; if omitted, uses UAVCAN__NODE__ID or leaves it unset.
• node_name: Optional node name for uavcan.node.GetInfo; defaults to com.manufacturer.project.ros2_bridge.
• can_iface: Optional PyCyphal CAN interface (e.g., socketcan:slcan0).
• can_mtu: Optional CAN MTU (e.g., 8).
• udp_iface: Optional UDP interface (e.g., 127.0.0.1).

Rule syntax

• Cyphal endpoint: port_id@node_id:dsdl_type
  • port_id can be omitted to use the fixed port ID (e.g., uavcan.node.Heartbeat.1.0).
  • @node_id is optional.
• ROS 2 endpoint: /topic:pkg/msg/Type.
• Rules use left -> right for direction.

Transform syntax

Transforms are assignment expressions separated by ;:

field=value

The left-hand side is a target field on the output message. The right-hand side is a Python expression evaluated with:

• msg (input message)
• float, int, bool, abs, min, max, math

Examples:

• data=float(msg.pascal)
• value=float(msg.data)

Security note: transforms use Python eval and must be treated as trusted input only.

Quick start (Docker)

Run the bridge container with the example config:

docker run --rm --net=host -v $(pwd)/tools/docker/example_bridge.yaml:/tmp/bridge.yaml:ro ponomarevda/ros2-cyphal-bridge:v0.3.0 --verbose

Notes

• Requires a ROS 2 environment (rclpy) for execution.
• Cyphal DSDL types are resolved via CYPHAL_PATH.
• Cyphal uavcan.node.GetInfo reports software_version from the package version (setuptools-scm tag).

Troubleshooting

• UDP/libpcap: On Linux, PyCyphal UDP capture relies on libpcap and raw packet access. Install libpcap (e.g., libpcap/libpcap-dev) and grant raw capture privileges (run as root or give cap_net_raw to the Python interpreter), per PyCyphal’s UDP transport docs.
• NumPy scalar conversion error: If you see TypeError: only 0-dimensional arrays can be converted to Python scalars (e.g., in yakut monitor) after a NumPy upgrade, try pinning NumPy to 2.3.5.