20261022-0322-key-box-n2k-connector Key Box 36: standard NMEA 2000 Micro-C connector for CAN2
- status: completed
- createdAt: 2026-10-22 03:22
- approvedAt: 2026-10-22 03:22
- relatedTask: 20261022-0322-key-box-n2k-connector
Context
章节标题：“Context”- Key Box 36 (
/srv/ybo/switch/key-box,tools/gen_key_box.py,tools/gen_key_pcb.pyBOARDS['key_box'],tools/gen_key_box_3d.py): CAN2 is an ISO1042 isolated transceiver (IO22 / IO23), side 2 powered from NET-S through L78L05, all side-2 parts in a no-pour island right of J2; the bus pins are AMPSEAL J2 29-35 (NET-H, NET-L, TERM, shield, AUX2, NET-S, NET-C) with R15 120 R selectable by a harness bridge. - GPIO: 21 of 22 used; IO8 spare. A standard socket needs none.
- Owner 2026-10-22: keep 36 keys; add a standard N2K socket (option A of the conversation: move the existing CAN2 to an M12 Micro-C socket, not a third CAN).
Proposal
章节标题：“Proposal”- Schematic: J5
Conn_01x05(board header, JST XH 5p vertical) on the CAN sheet, pins in Micro-C order 1 shield (CAN2_SHLD), 2 NET_S, 3 GND_N2K (NET-C), 4 NETH, 5 NETL. Panel socket M12 A-coded 5-pin male, front mount, PG9 / M16 thread, wired with a 5-wire lead to J5. Remove R15 and CAN2_TERM (NMEA 2000 devices never terminate). Keep the shield RC (R16 1M || C31 4.7 nF) to NET-C. J2 29-32, 34-35 not connected (spare), 33 AUX2. - PCB: J5 on the top side inside the island near L4 / D10; drop the
n2k_pins_no_pourkeepout (J2 no longer carries isolated nets); reroute, DRC. - 3D: M12 socket model on the lid above the island with an "N2K" legend; a mated drop-cable plug in the plugs view; re-render and re-export STEP.
- Docs: P05-key §2.1 / KEY-27 / §5, P05-key-design §2.3 pin table, P05-key-guide, the key-box README and docs copies; changelog.
Risks
章节标题：“Risks”- The board header and lead are a prototype choice; production may prefer a PCB-mount M12 with a sealed lid feed-through.
- NMEA 2000 shield handling (AC-coupled RC to NET-C) must be checked against the standard; the RC can be left unfitted.
Scope
章节标题：“Scope”switch: tools/gen_key_box.py, tools/gen_key_pcb.py, tools/gen_key_box_3d.py,
tools/render_key_box.py, regenerated key-box/ outputs and README.
docs: 3 files under bizplan/product/switch/key/, changelog, task / plan.
Alternatives
章节标题：“Alternatives”- Third CAN over SPI (MCP2518FD + isolated transceiver, IO8 as CS, INT shared with IO15): only needed for two independent N2K / CAN buses; not chosen.
- Leave N2K inside AMPSEAL J2: no standard drop cable, blocks NMEA certification.
Annotations
章节标题：“Annotations”- 2026-10-22: owner: "加一个标准的n2k插座" after the option A / B comparison.
- 2026-10-22: owner: drop Key Box 18; Key Box 36 is the only box product. Spec, design, guide, brief, index and the switch generators / READMEs no longer mention the reduced variant.