f0b7106932
- Add PCB 3D render as hero image, move schematic to bottom - Fix buck converter to SY8368AQQC (was TPS54560) - Add RCA stereo outputs, detail all audio outputs - Add button/connector table from Arduino MIDI schematic - Add connectivity table with correct USB port descriptions - Add dual micro HDMI outputs (touchscreen + debug) Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
116 lines
5.1 KiB
Markdown
116 lines
5.1 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. Reads Rekordbox-formatted USB sticks — no laptop required.
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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.
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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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- **RCA stereo pair** — Left (white) and Right (red) main outputs
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- **6.35mm (1/4") headphone jack**
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- **3.5mm headphone jack**
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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, fader, 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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All controls connect via JST PH connectors to the main PCB:
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| Connector | Controls |
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|---|---|
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| **J_PLAY** (6-pin) | Play button + LED, Cue button + LED |
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| **J_LOOP** (8-pin) | Loop In button + LED, Loop Out button + LED, Reloop button + LED |
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| **J_MASTER_TEMPO** (4-pin) | Master Tempo button + LED |
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| **J_ENCODER_BACK** (7-pin) | Back/browse rotary encoder + Back button + LED |
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| **J_TEMPO** (5-pin) | Tempo fader (analog ADC input) + Tempo Reset button + LED |
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| **J_JOG** (4-pin) | Jog wheel quadrature encoder (JOG1/JOG2) |
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| **J_TOUCH** (2-pin) | Jog wheel capacitive touch sensor |
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**Summary of buttons:** Play, Cue, Loop In, Loop Out, Reloop, Master Tempo, Tempo Reset, Back — each with a corresponding LED. Plus a tempo fader (analog), a browse/back rotary encoder, a jog wheel (quadrature encoder), and a jog wheel touch sensor.
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### Power
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- **USB-C power input** with **CH224K** USB PD negotiation (requests 20V @ 3A = 60W, peak draw 42.4W)
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- **SY8368AQQC** synchronous 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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| Port | Type | Speed | Purpose |
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|---|---|---|---|
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| **USB-A** | Full-size | USB 3.0 SuperSpeed | Rekordbox USB sticks |
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| **USB-A** | Full-size | Power only (no data) | Auxiliary power for gadgets/lights |
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| **USB-C** | Receptacle | USB 2.0 | General connectivity |
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| **Micro HDMI** | Type D | HDMI 1.4 | 10" touchscreen display |
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| **Micro HDMI** | Type D | HDMI 1.4 | Debug/secondary screen |
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| **Ethernet** | RJ45 (via CM5) | Gigabit | Network connectivity |
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Additional internal USB: USB 3.0 Type-A for the touchscreen's USB touch interface.
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- **HD3SS3220** USB-C orientation mux and **HD3SS3212** USB 3.0 signal switch for proper USB-C handling on the DJ stick port
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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
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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 (RCA + headphones)
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├── power.kicad_sch Power supply (USB-C PD, buck, LDOs)
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├── hdmi.kicad_sch Dual micro HDMI outputs + Ethernet
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├── usb_dj_ports.kicad_sch USB ports (DJ stick, aux power, connectivity)
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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, RCA jacks)
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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 fader 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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## Schematic
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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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