89 lines
3.7 KiB
Markdown
89 lines
3.7 KiB
Markdown
# TriMixxx
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A custom CDJ (Compact Disc Jockey) unit built from scratch around a Raspberry Pi CM5, designed to run [Mixxx](https://mixxx.org/) DJ software. Features a custom PCB, a custom 3D-printed chassis, and reuses original CDJ buttons and jog wheel for an authentic DJ experience.
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## What is this?
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TriMixxx replaces the internals of a CDJ with modern, open-source-friendly hardware while keeping the physical controls that DJs know and love. Plug in a Rekordbox-formatted USB stick, and you're ready to mix — no laptop required.
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## Hardware Architecture
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### Compute
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- **Raspberry Pi CM5** — runs Mixxx and handles audio playback, connected via dual DF40 100-pin high-density connectors
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### Audio
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- **TI PCM5242** — high-quality stereo DAC connected over I2S for low-latency audio output
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- **Dual audio outputs** — 6.35mm (1/4") and 3.5mm headphone jacks
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### MIDI Controller
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- **ATmega32U4** — acts as a USB MIDI class-compliant device, reading the original CDJ's buttons, encoders, and jog wheel and translating them into MIDI messages for Mixxx
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- **16 MHz crystal** oscillator for reliable USB timing
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### Power
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- **USB-C power input** with **CH224K** USB PD negotiation (requests 20V)
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- **TPS54560** buck converter stepping 20V down to 5V for the CM5 and peripherals
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- **AP2112K** 3.3V LDO for logic-level components
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- **AP2553W** USB power switches for safe hot-plug on DJ USB ports
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### Connectivity
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- **USB 3.0 Type-A port** — for Rekordbox USB sticks
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- **HDMI output** — for an optional display (waveforms, library browsing)
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- **USB-C** — power delivery and data
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- **HD3SS3220** USB-C orientation mux and **HD3SS3212** USB 3.0 signal switch for proper USB-C handling
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- **Ethernet** (via CM5) for network connectivity
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### Protection
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- **USBLC6-2SC6** ESD protection on USB data lines
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- **BZT52C3V3S** Zener diodes for voltage clamping
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## Chassis
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Designed in Fusion 360 with a custom top panel and bottom tray that fits the original CDJ form factor:
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- `CDJ-Top-Panel_v17.f3d` — top panel with cutouts for the jog wheel, buttons, and connectors
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- `CDJ-Bottom-Tray.f3d` — bottom enclosure
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## Project Structure
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```
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CDJ-MainBoard/ KiCad PCB project (6-layer board)
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├── CDJ-MainBoard.kicad_sch Root schematic
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├── arduino_midi.kicad_sch ATmega32U4 MIDI controller subsystem
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├── audio_outputs.kicad_sch DAC and audio output stage
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├── power.kicad_sch Power supply (USB-C PD, buck, LDOs)
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├── hdmi.kicad_sch HDMI output
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├── usb_dj_ports.kicad_sch USB 3.0 host port for DJ USB sticks
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├── test_points.kicad_sch Test points for debugging
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└── CDJ-MainBoard.kicad_pcb PCB layout
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JLC2KiCad_lib/ Component library (symbols, footprints, 3D models)
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kicad-thirdparty-footprints/ Third-party footprints (CM5, DAC, connectors)
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*.f3d Fusion 360 chassis models
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*.net Exported netlists (various revisions)
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```
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## Software Stack
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- **[Mixxx](https://mixxx.org/)** — open-source DJ software running on Raspberry Pi OS
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- **Rekordbox USB support** — reads Rekordbox-exported USB sticks for seamless library access
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- **MIDI mapping** — the ATmega32U4 presents as a standard USB MIDI device, so Mixxx sees the jog wheel, buttons, and knobs as native MIDI controls
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## Tools Used
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- **KiCad** — schematic capture and PCB layout
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- **Fusion 360** — mechanical design
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- **JLC2KiCad** — importing JLCPCB component libraries into KiCad
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- **JLCPCB** — PCB fabrication and assembly
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## License
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This is a personal hardware project. Feel free to use it as reference for your own builds.
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