Crazyflie Adapter

The Drone.Adapters.Crazyflie adapter flies a single Crazyflie 2.x through Crazyradio (or an in-process mock transport for CI and dry development).

Supported configuration (v0.3.0)

Not in this release: BLE, direct Crazyflie USB flight control, raw attitude setpoints, trajectory upload, parameter editing, firmware flashing, arbitrary log-block customization beyond the built-in readiness subscription, and multi-Crazyflie swarms.

Mock connection (no hardware)

{:ok, drone} =
  Drone.connect(:crazyflie,
    name: :cf_1,
    uri: "mock://ready",
    positioning: :flow,
    default_height_cm: 50
  )

:ok = Drone.connect_sdk(drone)
{:ok, battery} = Drone.query(drone, :battery)
:ok = Drone.takeoff(drone)
:ok = Drone.move(drone, :forward, 50)
:ok = Drone.rotate(drone, :cw, 90)
:ok = Drone.land(drone)
:ok = Drone.disconnect(drone)

connect_sdk/1 is a documented no-op that succeeds so shared missions stay portable across Tello, Sim, and Crazyflie.

Mock URI profiles:

Radio connection

{:ok, drone} =
  Drone.connect(:crazyflie,
    name: :cf_1,
    uri: "radio://0/80/2M/E7E7E7E7E7",
    positioning: :flow,
    usb_backend: MyApp.CrazyradioUSB
  )

usb_backend must implement Drone.Adapters.Crazyflie.USB. Without it, radio:// URIs return {:error, :usb_backend_unavailable}. The default backend is intentionally unavailable so Hex packages do not require native USB NIFs; wire your own libusb binding for hardware.

URI format

radio://<radio_index>/<channel>/<datarate>/<address>?safelink=1&timeout=1000

• radio_index — Crazyradio ordinal (0 for the first dongle)
• channel — 0–125 (Crazyradio 2.0: 0–100)
• datarate — 250K, 1M, or 2M
• address — 5-byte hex radio address (default E7E7E7E7E7)
• safelink=1 — negotiate Bitcraze SafeLink on open (default off)
• timeout — USB bulk timeout in milliseconds

Positioning and readiness

High-level position commands need a working estimator (Flow Deck, Lighthouse, or Loco Positioning). Pass positioning: :flow | :lighthouse | :loco (default :flow). Unknown values fail at connect with {:error, {:unsupported_positioning, value}}.

The adapter readiness gate (takeoff, land, move, rotate) checks:

• transport-reported battery (reject when unknown or below 15%)
• estimator_ready == true (reject when unknown/false)
• a non-nil telemetry timestamp

Emergency bypasses the readiness gate.

On connect, the session downloads the logging TOC and starts a block for pm.batteryLevel (or pm.vbat) plus sys.canfly. Radio telemetry/1 reads that cache; until the first log-data packet arrives, battery/estimator stay nil and motion commands fail closed with :telemetry_unavailable.

Safety policies can also enforce the same gates for motion commands:

Drone.connect(:crazyflie,
  name: :cf_safe,
  uri: "mock://ready",
  safety: [
    require_estimator: true,
    max_telemetry_age_ms: 500
  ]
)

When max_telemetry_age_ms is set, a missing telemetry_at is treated as stale.

Units

Linux USB permissions

Create /etc/udev/rules.d/99-crazyradio.rules:

SUBSYSTEM=="usb", ATTRS{idVendor}=="1915", ATTRS{idProduct}=="7777", MODE="0666"

Then reload rules: sudo udevadm control --reload-rules && sudo udevadm trigger.

macOS notes

Install a working libusb stack for your USB backend (Homebrew libusb is common). Grant the terminal / IDE USB access if the OS prompts. Prefer testing with mock:// before attaching a radio.

Firmware / protocol compatibility

The adapter accepts CRTP protocol versions 4–12. Unsupported versions fail at connect with {:error, {:unsupported_protocol, version}}.

Keep firmware within the range documented by Bitcraze for high-level commander (TAKEOFF_2, LAND_2, GO_TO_2).

Safety checklist

1. Test the mission on mock://ready first
2. Confirm positioning deck / system is calibrated
3. Clear prop / people hazards
4. Keep Drone.emergency/1 reachable
5. Treat radio unplug / link loss as unknown flight state — never as a successful land

Capability differences

Troubleshooting

Further Reading

• Deferred scope: v0.3.0 Deferred Work
• Research-style refs: Further Reading — Platforms
• Official: CRTP, Crazyradio USB, Logging