BarnacleBoy
ef9a7f40a8
- Mechanical HDMI A/B switch for internal/external display toggle - DisplayLink rejected: no ARM drivers exist - 10-port layout split across 4 surfaces - Port side: 4x USB-A, 1x USB-C data, 1x USB-C PD out - Starboard: Ethernet, HDMI out, 3.5mm audio - Bow: USB-C power input + fan exhaust - Stern: handle, SD reader, Kensington lock - Updated BOM with HDMI switch, panel-mount cables, SD reader - Cost estimate now ~58
61 lines
2.3 KiB
Markdown
61 lines
2.3 KiB
Markdown
# Design Decisions
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## Build Approach
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Wooden case with salvaged laptop lid (screen + hinge) as the canopy. Approximate briefcase dimensions, with the display panel setting minimum width and depth.
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## Salvage Exclusions
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- **Webcam:** Scrapped. Proprietary pinout, not worth reverse engineering.
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- **Keyboard/trackpad:** Proprietary connectors, not reusable.
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- **RAM:** DDR3L soldered, wrong generation.
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- **SSD:** Owner repurposed.
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- **WiFi card:** Intel 7265NGW needs M.2 E-key, OPi5 base lacks it.
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## Case Orientation & Nomenclature
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User sits at the **stern**, facing the **bow**. Hinge axis runs port-to-starboard along the bow edge.
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### Base (wooden enclosure)
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| Term | Surface | Notes |
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|------|---------|-------|
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| **Deck** | Top | Keyboard, controls, SBC access |
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| **Keel** | Bottom | Sits on table |
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| **Bow** | Back edge (spine side) | Power input, heat exhaust, farthest from user |
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| **Stern** | Front edge (lip side) | User-facing, keyboard near here |
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| **Port** | Left (facing bow) | |
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| **Starboard** | Right (facing bow) | |
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### Canopy (laptop lid + screen)
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| Term | Surface |
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|------|---------|
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| **Canopy dorsal** | Outside of lid |
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| **Canopy ventral** | Screen side |
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### Bow Wall Functions
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- Power input (USB-C for IP5389 board charging)
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- Exhaust fans blowing away from user
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- Heat management surface
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## Carry Handle
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Stern edge (lip). Screen is lightweight, hinge is rigid, and a lid latch is planned — so the canopy-open-under-gravity concern is handled. Keeps the bow wall dedicated to power input and exhaust.
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## Power System
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IP5389 power bank board (preliminary). All-in-one: charging, BMS, USB-C PD output. See [power-system.md](power-system.md) for details.
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## Video Output
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Mechanical HDMI A/B switch (passive, no power). Routes OPi5's single HDMI to either the internal eDP-to-HDMI controller or a panel-mount HDMI jack on the starboard side. DisplayLink doesn't work on ARM — no drivers exist. Dual simultaneous display is not possible on the base OPi5.
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## Input Device
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ThinkPad TrackPoint keyboard (specific model TBD based on availability). Chosen for built-in TrackPoint pointer and 15.6" deck space compatibility.
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## Carry Handle
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Stern edge (lip). Screen is lightweight, hinge is rigid, and a lid latch is planned — so the canopy-open-under-gravity concern is handled. Keeps the bow wall dedicated to power input and exhaust.
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