BrickPipe

Brickpipe provides a JSON-based Inter-Process Communication (IPC) interface to interact with Pybricks hubs. It communicates via standard input (stdin) for commands and standard output (stdout) for events.

Each message (incoming or outgoing) must be a single-line JSON object.

Message Format

All messages are JSON objects that contain an event_type field.

{
  "event_type": "event_name",
  "other_field": "value"
}

Incoming Events (Commands)

These commands are sent to the script via stdin.

Outgoing Events

These events are sent from the script via stdout.

Example Usage

Connecting and Running a Script

1. Connect via bluetooth:

• Input: {"event_type": "connect_to_hub", "conn_type": "ble", "hub_name": "Robot"}
• Output: {"event_type": "hub_connected"}

2. Download and Run a Program:

• Input: {"event_type": "recompile_run", "program_path": "main.py"}
• Output:
  • {"event_type": "download_progress_update", "percentage": 50.0}
  • {"event_type": "download_progress_update", "percentage": 100.0}
  • {"event_type": "program_started"}
  • {"event_type": "hub_printed_line", "line": "Hello, World!"}
  • {"event_type": "program_complete"}

3. Handling a Compile Error:

• Input: {"event_type": "recompile_run", "program_path": "broken.py"}
• Output: {"event_type": "compile_error", "traceback": "..."}