CAC Hub

A central dashboard for managing multiple Pioneer CAC CD Autochanger nodes across your network.

The CAC Hub connects to one or more CAC Controller nodes via REST API and WebSocket, providing a unified interface for monitoring and controlling all your CD autochangers from a single location.

Overview

                    ┌──────────────────┐
                    │    CAC Hub        │
                    │  (this app)       │
                    │  Port 4000        │
                    └───┬────┬────┬────┘
          REST API +    │    │    │    REST API +
          WebSocket     │    │    │    WebSocket
        ┌───────────────┘    │    └───────────────┐
        v                    v                    v
┌───────────────┐  ┌───────────────┐  ┌───────────────┐
│  Living Room  │  │    Studio     │  │      Bar      │
│  CAC-V3000    │  │  CAC-V5000    │  │  CAC-V180M    │
│  RPi + Node   │  │  RPi + Node   │  │  RPi + Node   │
│  Port 3000    │  │  Port 3000    │  │  Port 3000    │
└───────────────┘  └───────────────┘  └───────────────┘

Each node runs the standalone CAC Controller app and remains fully operational on its own. The Hub is purely additive — it aggregates status and provides centralized control.

Features

Dashboard

• Live node status cards with real-time player state, disc, track, and mode for all connected nodes
• Quick controls — Play, Pause, Stop, Next directly from the dashboard
• Power control — On/Off button per node (GPIO relay) in the card header, configurable per node
• Connection monitoring with automatic reconnect and health checks

Node Control

• Full player control — Transport (play, pause, stop, next, previous), volume, speed for both players
• Play modes — Continuous, Gapless, Shuffle
• Library browser — Search, browse, and load CDs from any node
• Playlists — View and start playlists on any node
• Scanner — Start/abort CD scans remotely with live progress
• Statistics — Play statistics per node with top tracks (with covers), top CDs, top artists, genre distribution, and activity charts
• Backup / Restore — Export and import full node database backups (JSON) and cover images (ZIP) via the Hub
• Direct link to each node's full web interface for advanced features

Management

• Add/remove nodes with URL and API key
• Test connection before adding a node (auto-fills name, room, model)
• GPIO pin configuration per node in the edit modal (proxied to node settings)
• Hub settings — Name, port, language
• Bilingual UI — German and English

Technical

• Proxy API — All requests to nodes are proxied through the Hub with API key authentication
• WebSocket aggregation — Real-time events from all nodes are merged and forwarded to Hub clients
• Cover image proxy — Album covers from nodes are served through the Hub
• Auto-reconnect — Lost node connections are automatically retried
• Health checks — Periodic status polling to detect offline nodes

Prerequisites

• Node.js >= 18.x (20 LTS recommended)
• npm (included with Node.js)
• Build tools for native SQLite module: build-essential, python3
• One or more CAC Controller nodes configured with API keys

Quick Start

git clone https://github.com/NFDiJee/cac-controller-hub.git
cd cac-controller-hub
npm install
npm start

Open http://<your-ip>:4000 in any browser.

Node Setup

Each CAC Controller node must have an API key configured for the Hub to connect:

1. Open the node's web interface (http://<node-ip>:3000)
2. Go to Settings (gear icon)
3. Under Hub / Network, set:
   • Node Name (e.g., "Living Room")
   • Room (e.g., "Ground Floor")
   • API Key — Click "Generate" for a random 32-character key
4. Save settings

Then add the node in the Hub under Settings > Add Node:

• URL: http://<node-ip>:3000
• API Key: The key you generated on the node
• Click Test Connection to verify, then Add

Node Hardware Note

Each Node (CAC Controller instance) connects to a Pioneer CAC changer. There are two connection options:

Option A: External USB-RS232 Adapter (simple)

• USB-to-Serial adapter (FTDI, PL2303 or CH340) + RS-232C cable with 15-pin D-Sub connector
• Port: /dev/ttyUSB0

Option B: Internal RPi Zero W Integration (advanced)

• Raspberry Pi Zero W installed inside the CAC-V3000 case
• TTL serial signals tapped at the RSIF board input (handoff from MCDR board) -- both boards under the right side cover (viewed from front)
• Voltage divider (1kOhm / 2kOhm) for 5V to 3.3V level shifting on RX line
• Power: Hi-Link HLK-PM01 (230V AC to 5V DC) from AC inlet before power switch
• Relay (JQC-3FF-S-Z, Active HIGH) on GPIO17 for power control
• Network: Mini USB to USB-A female adapter + TP-Link TL-WN722N WiFi stick with SMA connector to external antenna, or USB Ethernet adapter
• Port: /dev/ttyAMA0

DIP Switch: On the CAC-V3000, DIP switch 3 must be set to ON for 9600 baud (behind front door).

See the CAC Controller documentation for detailed hardware setup instructions.

REST API

Hub Endpoints

Method	Endpoint	Description
GET	/api/hub/status	Hub overview with all nodes
GET	/api/nodes	List all nodes with status
POST	/api/nodes	Add a node { url, api_key, name, room }
GET	/api/nodes/:id	Get single node status
PUT	/api/nodes/:id	Update node
DELETE	/api/nodes/:id	Remove node
POST	/api/nodes/test	Test connection { url, api_key }

Proxy Endpoints

Method	Endpoint	Description
ALL	/api/nodes/:id/proxy/*	Proxy any API call to a node
GET	/api/nodes/:id/cover/*	Proxy cover images from a node
GET	/api/nodes/:id/proxy/backup/covers	Download cover images ZIP from a node
POST	/api/nodes/:id/proxy/backup/covers	Upload cover images ZIP to a node

The proxy automatically adds the stored API key to forwarded requests. Any endpoint available on the node can be called through the proxy — player control, library CRUD, playlists, scanner, settings, MusicBrainz, and more. Binary content (cover images, ZIP archives) is proxied via dedicated routes.

Hub Settings

Method	Endpoint	Description
GET	/api/settings	Get hub settings
PUT	/api/settings	Update hub settings

WebSocket

Connect to ws://<hub>:4000 for real-time updates from all nodes:

Message Type	Description
init	Initial state with all nodes
nodeOnline	A node connected
nodeOffline	A node disconnected
nodeState	Full state update from a node
nodeEvent	Forwarded event from a node (playerState, scanProgress, etc.)

Project Structure

cac-controller-hub/
├── server.js                 # Express + WebSocket server (port 4000)
├── package.json
├── cac-hub.service           # Systemd unit file
├── src/
│   ├── database.js           # SQLite database (nodes, settings)
│   ├── node-manager.js       # WebSocket connections to nodes, health checks
│   ├── routes.js             # Hub API + proxy routes
│   └── websocket.js          # WebSocket for Hub UI clients
├── public/
│   ├── index.html            # Hub SPA (dashboard, node control, settings)
│   ├── css/
│   │   └── app.css           # Dark theme styling
│   └── js/
│       ├── app.js            # Hub frontend logic
│       └── i18n.js           # Translations (DE/EN)
└── data/
    └── cac-hub.db            # SQLite database (auto-created)

Installation on Raspberry Pi

See INSTALL.md for step-by-step instructions.

The Hub can run on the same Raspberry Pi as a node, or on a separate device. Use a different port (default: 4000) to avoid conflicts.

Configuration

All settings are configurable via the web UI under Settings:

Setting	Default	Description
Hub Name	CAC Hub	Display name
Port	4000	HTTP server port
Language	auto	Auto-detect, German, or English
Reconnect Interval	10000	ms between reconnect attempts
Health Check Interval	30000	ms between health checks

Updating

cd /opt/cac-controller-hub
git pull
npm install
sudo systemctl restart cac-hub

License

MIT License — Copyright (c) 2025 Dirk Jensen — See LICENSE for details.

Related

• CAC Controller (Node) — The standalone controller for each Pioneer CAC autochanger

Disclaimer

This is an independent open-source project. It is not affiliated with, endorsed by, or connected to Pioneer Corporation or any of its subsidiaries. "Pioneer" and "CAC" are trademarks of Pioneer Corporation.