Lite SDK2

Host-side SDK for Berkeley Humanoid Lite. It gives a pure-Python (no rclpy) process on a host machine a publisher/subscriber API onto a robot running the bar_ros2 control stack, over CycloneDDS.

What it provides

• Message types — re-exported from bar_msgs_dds: MITCommand, JointState, ControlMode, SafetyStatus, StandbyState (+ Header/Time). These carry the rmw type-name mangling, so they interoperate with a live bar_ros2 graph.
• A message-agnostic channel layer — a process-wide DDS participant, NIC selection, realtime-safe write(), discovery wait, and callback subscriptions.
• A topic + QoS registry — per-type defaults matching the bringup, so publisher(MITCommand) "just works"; override with topic=/qos=.
• CLIs — lite-sdk2-monitor and lite-sdk2-control.

Install

cd Lite-SDK2
uv sync          # uses the in-tree bar_msgs_dds via [tool.uv.sources]
uv run pytest

CycloneDDS is pulled in as a dependency. As a dependency of another project:

dependencies = [
    "lite_sdk2 @ git+https://github.com/Berkeley-Humanoids/Lite-SDK2.git",
]

DDS model

Direction	Message	ROS topic	DDS topic	QoS
host → robot	MITCommand	/remote_policy_controller/command	rt/…	reliable, depth 4
robot → host	JointState	/lite/joint_states	rt/…	reliable, depth 10
robot → host	ControlMode	/control_mode	rt/…	reliable
robot → host	SafetyStatus	/safety_status	rt/…	reliable
robot → host	StandbyState	/standby_controller/state	rt/…	transient-local (latched)

ROS topic names get the rt/ prefix on the wire; the wire typename is pkg::msg::dds_::Name_ (the rmw mangling). Both are handled by bar_msgs_dds.

Usage

import lite_sdk2
from lite_sdk2 import MITCommand, JointState, zero_mit_command

lite_sdk2.initialize(domain_id=0, network_interface="enp2s0")

sub = lite_sdk2.subscriber(JointState)          # topic + QoS from the registry
sub.initialize()
state = sub.read(timeout=0.5)

pub = lite_sdk2.publisher(MITCommand)
pub.initialize()
pub.wait_for_reader(timeout=2.0)                # optional discovery wait
pub.write(zero_mit_command(state.name, damping=2.0))   # safe "park" command

CLIs

uv run lite-sdk2-monitor enp2s0 joint_states          # print decoded JointState traffic
uv run lite-sdk2-monitor enp2s0 control_mode
uv run lite-sdk2-control enp2s0 damping               # stream damping until Ctrl+C
uv run lite-sdk2-control enp2s0 disable               # zero-torque burst, then exit

Both take the network interface as the first argument; --domain-id selects the ROS_DOMAIN_ID. lite-sdk2-control discovers the joint order from /joint_states.

Adding or changing a message

Messages live in bar_ros2, not here. Edit bar_msgs/msg/*.msg, run pixi run gen-dds to regenerate bar_msgs_dds, and the new/changed type is available through lite_sdk2 automatically. There is no schema, IDL, or Rust mirror to keep in sync in this repo anymore.

Architecture

bar_msgs (.msg)      ← single source of truth, in bar_ros2
   │ pixi run gen-dds
bar_msgs_dds         ← generated cyclonedds types + topic/QoS conventions
   │ pip dependency
lite_sdk2 (this repo) ← message-agnostic channel layer + CLIs
   │
host apps            ← policy runners, Lite-Gravity-Compensation, data tools