Pi Multi-FX — Boss-Size Touchscreen Pedal

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)

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

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

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

🎸 Pi Multi-FX — Boss-Size Touchscreen Concept