# 🎸 Pi Multi-FX — Boss-Size Touchscreen Concept

1590BB Enclosure · 5" DSI Touch · I2S HAT Stack

### Exploded View — Stackup

### Component Stack — 1590BB Build

Enclosure | 1590BB diecast aluminum
| 140×78×48mm — Boss compact size
Touchscreen | Waveshare 5" DSI
| 800×480, capacitive multi-touch
| ✅ Native RPi DSI — no HDMI needed
| ✅ Fits 1590BB face with border
Brain | RPi 4B (2GB+)
| DietPi, headless, JACK + Python DSP
Audio | PCM1808+PCM5102 I2S HAT
| Custom 65×56mm PCB (already designed)
| Stacking header passes GPIO to display
| ✅ < 10ms round-trip
Connectivity | USB-C (power only)
| WiFi for `pedal.local` web UI
| Bluetooth for wireless MIDI
I/O Panel | Side-mounted: Input, Send, Return, Output
| USB-C power, MIDI DIN (optional)
Est. BOM (5 pcs) | ~$175-200 per unit

### 📐 Mechanical Stack

Touch layer 5" glass + front bezel
Display PCB 8mm standoff
RPi 4B 10mm standoff (above HAT)
Stacking header GPIO pass-through
I2S HAT 6mm standoff → enclosure base
Total depth ~38-42mm (fits 48mm 1590BB)

### 🔌 Internal Wiring

Display → DSI ribbon (15-pin) → RPi DSI port
I2S HAT → mounts on RPi GPIO via stacking header
Audio jacks → flying leads to HAT I/O pads
Power → USB-C → RPi → 5V rail → I2S HAT
Footswitches (optional) → GPIO via HAT passthrough

### ⚠️ Things to Sort

① Jacks: Need right-angle PCB-mount jacks for side fit — or wire to chassis-mount jacks on enclosure walls
② DSI ribbon: Needs careful routing past the stacking header. 15-pin flat flex cable, keep away from I2S traces
③ I2S HAT Rev: The current PCB is 65×56mm (1590B). For 1590BB you could make it slightly wider to match — but it works as-is
④ Heat: RPi 4B in an enclosed box gets warm. Consider a vent slot or small fan on the side

### 📏 Size Comparison vs Boss Pedal