- docs/sbc-selection.md: full rewrite for OPi 3B specs (RK3566, 8GB, 256GB eMMC, built-in WiFi) - README.md: SBC description, checklist, components table, quick ref, cost estimate - docs/parts-list.md: SBC marked purchased, eMMC/controller/WiFi changes - docs/design-decisions.md: WiFi exclusion reason, native eDP, power input - docs/salvage-analysis.md: WiFi card not needed, cooling fan, summary tables - docs/storage-architecture.md: rewritten for 256GB eMMC primary boot - docs/usb-expansion.md: 2x USB3 native, port allocation, power budget - docs/port-layout.md: OPi3B port differences (eDP, power-only USB-C, built-in WiFi) - docs/power-system.md: lower power draw context
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Port Layout
Overview
10 accessible ports + SD reader + Kensington lock, split across four case surfaces. Built-in WiFi+BT eliminates need for USB dongles.
Port Side (Left, Facing Bow)
Data connections. "Plug and unplug frequently" zone.
| Port | Count | Source | Notes |
|---|---|---|---|
| USB-A 3.0 | 4 | Powered hub | Flash drives, peripherals, hardware |
| USB-C (data) | 1 | Powered hub | Modern peripherals, data transfer |
| USB-C PD out | 1 | IP5389 board | Phone charging, 5V/??W |
Starboard Side (Right, Facing Bow)
Networking + AV. "Plug in and leave" zone.
| Port | Count | Source | Notes |
|---|---|---|---|
| Ethernet RJ45 | 1 | OPi3B native | Gigabit, panel-mount extension |
| HDMI out | 1 | HDMI A/B switch | External display, switched from internal |
| 3.5mm audio out | 1 | OPi3B native | Headphones, speakers, line-out |
Bow Wall (Back Edge, Spine Side)
Power and cooling. No data ports.
| Feature | Notes |
|---|---|
| USB-C power input | For IP5389 board charging (5V/3A) |
| Fan exhaust grilles | Blowing away from user |
Stern Edge (Front Edge, Lip)
User-facing. Clean for typing.
| Feature | Notes |
|---|---|
| Carry handle | Stern-mounted per design decision |
| SD card reader | Panel-mount, for camera cards / quick imaging |
| Kensington lock slot | Physical security |
Internal Components
| Component | Connection |
|---|---|
| Powered USB hub (10-port) | Decased, wired internally. Feeds all USB-A and USB-C data ports. |
| HDMI A/B switch (mechanical) | Passive toggle. OPi3B HDMI in, two outputs (internal display + starboard panel jack). |
| eDP-to-HDMI controller | Connected to A/B switch output A. Drives internal display — may be unnecessary if native OPi3B eDP works with panel |
Constraints
- OPi3B has one HDMI output. The A/B switch selects internal or external — not both simultaneously.
- OPi3B has a native eDP port — if the Innolux N156HGE-EAB panel pinout matches, the external controller board is not needed.
- DisplayLink USB graphics adapters do not work on ARM Linux (no drivers). Not a viable path for dual display.
- Dual simultaneous display would require a dual-HDMI SBC.
- USB-C on the OPi3B is power only — no DisplayPort alt mode. All video goes through HDMI or native eDP.
- Built-in WiFi 5 + BT 5.0 on the OPi3B — no USB dongles needed for wireless connectivity.
- Two native USB 3.0 ports available for direct connections (keyboard, mouse) without hub contention.