Documenting Packets

SPaC-Kit includes a Sphinx extension that automatically generates comprehensive documentation for CCSDS packet definitions. This is the standout feature of SPaC-Kit, enabling missions to maintain living documentation that stays synchronized with packet definitions.

Overview

The spac_kit.autodocs Sphinx extension:

  • Discovers all packet definitions from installed plugins

  • Generates RST stub files automatically

  • Creates formatted documentation with field tables

  • Links field names to detailed descriptions

  • Styles output with mission-specific CSS

This eliminates manual documentation maintenance and ensures packet specs stay current with code.

Quick Start

Add to your Sphinx conf.py:

extensions = [
    'sphinx.ext.autodoc',
    'spac_kit.autodocs',  # Add this line
]

# Configure which modules to document
spacdocs_packet_modules = [
    'ccsds.packets.europa_clipper.ecm',
    'ccsds.packets.europa_clipper.status',
]

Then build your docs:

sphinx-build -b html docs/ docs/_build/html

The Sphinx Extension

The extension provides the .. spacdocs:: directive for documenting individual packets, and automatically generates a complete packet index.

Configuration

In your conf.py:

extensions = ['spac_kit.autodocs']

# Required: List of Python module paths containing packet definitions
spacdocs_packet_modules = [
    'ccsds.packets.your_mission.telemetry',
    'ccsds.packets.your_mission.commands',
]

The extension will:

  1. Scan each module for _BasePacket instances

  2. Generate an RST stub file for each packet

  3. Create a master index file (_packet_index.rst)

  4. Copy styling resources to your _static directory

Using the spacdocs Directive

Manual usage (the extension does this automatically):

Sensor Data Packet
==================

.. spacdocs:: ccsds.packets.europa_clipper.ecm.sensor_data

This generates:

  • Summary table with all fields, types, bit lengths, and offsets

  • Detail sections for each field with full attribute listings

  • Interactive tooltips showing field descriptions

  • Hyperlinks from summary to details

Generated Documentation Structure

For each packet, the extension creates:

Summary Section

A table showing:

  • Field names (clickable, with tooltip descriptions)

  • Data types (with array notation if applicable)

  • Bit lengths

  • Bit offsets (calculated automatically)

  • Byte order

Detail Sections

For each field:

  • Field name as section header

  • Full description

  • Complete attribute table (data type, bit length, offset, byte order, array shape, array order)

Advanced Features

Field Descriptions

Add descriptions to your packet fields:

PacketField(
    name='status',
    data_type='uint',
    bit_length=8,
    description='System status flags: bit 0=power, bit 1=thermal'
)

Descriptions appear as tooltips in the summary table and as paragraph text in detail sections.

Array Fields

Array fields are automatically formatted:

PacketArray(
    name='sensor_grid',
    data_type='uint',
    bit_length=16,
    array_shape=(32, 32)
)

Appears in documentation as: uint[32,32]

Directory Structure

After building, your docs directory contains:

docs/
├── conf.py
├── index.rst
├── _static/
│   ├── spac-kit.css          # Auto-copied
│   └── circle-info.svg       # Auto-copied
├── _autopackets/             # Auto-generated
│   ├── packet_name1.rst
│   ├── packet_name2.rst
│   └── ...
└── _packet_index.rst         # Auto-generated

Include _packet_index.rst in your main toctree:

.. toctree::
   :maxdepth: 2

   introduction
   _packet_index
   api

Integration Example

Complete conf.py example:

# Sphinx configuration

project = 'Europa Clipper Packets'
extensions = [
    'sphinx.ext.autodoc',
    'sphinx.ext.napoleon',
    'spac_kit.autodocs',
]

# SPaC-Kit configuration
spacdocs_packet_modules = [
    'ccsds.packets.europa_clipper.ecm',
    'ccsds.packets.europa_clipper.ice',
    'ccsds.packets.europa_clipper.mimi',
]

# HTML output options
html_theme = 'sphinx_rtd_theme'
html_static_path = ['_static']

Main documentation file (index.rst):

Europa Clipper Packet Documentation
====================================

.. toctree::
   :maxdepth: 2

   overview
   _packet_index
   usage