openbricks 1.21.1

openbricks — host-side CLI + MuJoCo-backed simulator for the openbricks MicroPython firmware. Flash, list, run, upload, log; ``openbricks sim`` for the physics simulator.

openbricks (host CLI + sim)

Host-side tooling for openbricks hubs — same UX as pybricksdev, built on commodity Python tooling (bleak, esptool, mpremote). One package, one console script: openbricks flash / list / run / upload / stop / log. The MuJoCo-backed simulator is built in too — openbricks sim … opens the sim's CLI when the [sim] extra is installed.

Website: https://openbricks.dev · Documentation: https://docs.openbricks.dev

Install

Recommended — with pipx so the CLI lands in an isolated venv and avoids the "externally managed environment" error on modern macOS / Linux distros:

pipx install openbricks            # CLI only (lightweight; bleak / esptool / mpremote)
pipx install 'openbricks[sim]'     # CLI + MuJoCo physics simulator

Plain pip works too:

pip install openbricks
pip install 'openbricks[sim]'

For development against a repo checkout (editable install):

pip install -e 'tools/openbricks[sim]'

[sim] adds mujoco (~50 MB, native OpenGL) and numpy — most users (flash + run + log) don't need it. Without [sim], openbricks sim … prints a helpful "pip install openbricks[sim]" hint instead of crashing.

Note: binary wheels (manylinux, macOS universal2, Windows AMD64; CPython 3.9–3.13) ship on PyPI since 0.10.3, so installs are toolchain-free on common platforms. On anything outside that matrix, pip falls back to the sdist and compiles the bundled native extension (openbricks_sim._native), which needs a C compiler + Python headers.

Commands

flash — program a hub

openbricks flash \
    --name RobotA \
    --port /dev/tty.usbserial-XXXX \
    --firmware native/micropython/ports/esp32/build-openbricks_esp32s3/firmware.bin

Writes the firmware image and bakes the hub's BLE advertising name into NVS. --name is mandatory: two hubs with the same name can't be individually addressed over BLE.

Port syntax: /dev/ttyUSB0 (Linux), /dev/cu.usbserial-* (macOS), COM5 (Windows).

Useful flags: --chip esp32s3, --baud 921600, --skip-erase (faster dev loop, keeps stale NVS).

list — scan for hubs

openbricks list [--timeout 5.0] [--all]

Runs a BLE scan and prints every named device found, sorted by RSSI (strongest first). --all includes unnamed devices too.

run — stage and launch; button stops it; client exits on stop

openbricks run -n RobotA examples/hello.py

Stages the script to /program.py (same target as upload) and triggers the hub's launcher to execute it immediately. Output streams back to your terminal in real time.

• Button stop. Pressing the hub button while the program runs raises KeyboardInterrupt via the same launcher path upload+button uses. The client sees the clean "stopped by button press" line and exits.
• Program completion. When the program finishes (or raises), the client disconnects and exits — same as pybricksdev run.
• Script persists. Because run stages to /program.py, the hub can re-run the last program via a button press without another upload. upload and run differ only in whether the client auto-launches after upload.

Stderr (e.g. exception tracebacks) arrives after stdout and is surfaced with a blank-line separator. No paste-mode === echo — raw-paste mode is clean.

stop — interrupt the running program

openbricks stop -n RobotA

Sends a single Ctrl-C byte over the NUS REPL bridge, which MicroPython surfaces as KeyboardInterrupt. Useful when openbricks run has already exited but the hub's still chewing on a long-running user program.

upload — stage a script; hub button launches it

openbricks upload -n RobotA examples/wander.py

Writes the script to /program.py on the hub. The code does not run automatically. Place your robot, press the program button (GPIO 4), and the program starts. Press again to stop it mid-run.

(Pybricks calls this same operation download from the hub's "download to me" perspective. We name by direction-of-data-travel — bytes flow up to the hub, hence upload.)

This works because the firmware ships a frozen main.py that:

1. Brings BLE + REPL bridge up immediately (so openbricks run / upload / stop are always reachable, even when no program is running).
2. Instantiates the board's Hub, which wires the BLE-toggle button (short-press on GPIO 5) with LED feedback.
3. Watches the program button (GPIO 4) via openbricks.launcher.run() — a short-press runs /program.py, a second short-press raises KeyboardInterrupt in the running program.

Two separate pins (4 for program, 5 for BLE toggle), each handled by short-press only — no duration-based dispatch.

Pass --path /alt.py to stage at a different filename (if you've written your own main.py that reads from there).

Tests

cd tools/openbricks
PYTHONPATH=. python -m unittest discover -s tests -t .

No real hardware needed — esptool, mpremote, and bleak are mocked.