20261028-1709-air-hub-esp32-c5-module Replace the ESP32-C6 with an ESP32-C5 module on all three Air Hub products

status: completed
createdAt: 2026-10-28 17:09
approvedAt: 2026-10-28 17:16
relatedTask: 20261028-1709-air-hub-esp32-c5-module

Context

Current ESP32 use in the Air Hub family (spec R1.x, reference-board revision D):

Product	Part	Role	Interface
Air Hub (AH-19), Air Hub Pro (AH-20)	ESP32-C6-MINI-1-N4 (LCSC C5736265, $2.83 @1.3k)	Wi-Fi uplink and configuration link to Linux; TWAI unused, no path to CAN (`GW-13`)	ESP-Hosted over SDIO (C6 IO18–IO23 to core-board SDMMC), UART4 side channel, EN/BOOT GPIO
Air Hub Mini (AH-21)	ESP32-C6-WROOM-1-N8 (C5366877, $2.98 @1.3k)	Only controller, Wi-Fi only uplink, TWAI as YBO CAN (`GW-14`), flashes the MG24 module	USB Serial/JTAG on IO12/IO13 for service; 16 of 23 GPIOs used

ESP32-C5 facts (Espressif ESP32-C5-WROOM-1/1U datasheet v1.3, 2026-09-03, official release):

Two module families exist. ESP32-C5-WROOM-1 (datasheet v1.3, 2026-09-03): 18.0 × 27.5 × 3.3 mm, 29 pins, up to 22 GPIOs, −40…+85 °C; order codes N4, N4R2, N8R2, N16R2, N8R8, N16R8, N32R8. ESP32-C5-MINI-1 (datasheet v1.4, 2026-09-14, official release since v1.0): 15.4 × 21.3 × 2.4 mm, 65 pads, 22 GPIOs, −40…+85 °C; order codes MINI-1-N4 (ESP32-C5HF4) and MINI-1-N8R2, plus 1U variants. (Correction 2026-10-28: the first draft of this plan wrongly said no C5-MINI exists; reported by the hardware session.)
Dual-band Wi-Fi 6 (2.4 GHz and 5 GHz, 1T1R), BLE 5 (Core 6.0), 802.15.4 (Thread 1.4, Zigbee 3.0).
CAN FD controller (ISO 11898-1:2015), usable for Classical CAN 2.0B at 500 kbit/s.
SDIO slave on IO7–IO10, IO13, IO14; not supported on chip revisions v0.0/v0.1. USB Serial/JTAG also sits on IO13/IO14.
Linux host: Espressif esp-hosted-linux lists ESP32-C5 for SDIO and SPI (https://github.com/espressif/esp-hosted-linux).
Price: no LCSC listing found; DigiKey EU about EUR 3.13 @250 for WROOM-1-N4, Octopart about $3.20 (2026-10-28). Treated as an estimate until quoted.

The 2026-10-25 evaluation (design appendix §3.1) already rated the C5-WROOM-1 a worthwhile upgrade for the Mini; this task extends it to all three products and makes it current.

Hardware in /srv/ybo/switch (schematics, PCBs, renders, handover package) is not regenerated from this repository; documents will state that they still show the C6.

Proposal

Part numbers (recommended):

Air Hub and Air Hub Pro: ESP32-C5-WROOM-1-N4 (co-processor; ESP-Hosted firmware fits 4 MB, no PSRAM needed).
Air Hub Mini: ESP32-C5-WROOM-1-N8R2 (keeps 8 MB flash for A/B images of its own firmware and the MG24 images; 2 MB PSRAM adds headroom for the Wi-Fi 6 stack).
Both share the WROOM-1 footprint, so the carrier and the Mini use one footprint and pin geometry. Alternative: N8R2 on all three for one order code (about +$0.3–0.5 per Linux board, estimate).

Document changes (product package, Air Hub only):

Spec P05-air-hub.md: §1, §2.1 product table, §2.4 radio/CAN rows, §2.5 Mini, GW-13/GW-14 wording (CAN FD controller in Classical CAN mode), REG rows add 5 GHz (EN 301 893, DFS as client, 5150–5350 MHz indoor-use restriction to be checked for on-board vessel use); new open item for 5 GHz on vessels and C5 chip revision ≥ v0.2 for SDIO; change-log row.
Design appendix: Wi-Fi uplink row, Mini controller section (pin plan, USB on IO13/IO14, strapping pins), §3.1 alternatives table turned into the decision record (C6 becomes the superseded option), CAN source row.
Reference-board page: block diagrams, SDIO pin table (C5 IO7–IO10, IO13, IO14), Mini pin table reassigned to the C5's 22 GPIOs, BOM rows and §6 totals recalculated with the estimate, a note that schematics/PCB/renders still show the C6 and the carrier footprint grows from MINI-1 to WROOM-1 (18 × 27.5 mm); open hardware items list the redo.
Guide, index, P05-switch.md model line, emc-safety-certification.md (5 GHz test scope). Historical evaluations (platform-combinations.md, industrial-linux-and-radio.md) keep their content; only the "selected" markers are updated.

Governance: product plan P5/§5, compliance matrix Air Hub row (5 GHz), open questions AIR-O-03, business-plan cost sentence — done together with task 20261028-1704-governance-sync-switch-rev-d, which this task blocks.

Key (ESP32-C6-MINI-1) is not changed.

Risks

Carrier layout: WROOM-1 is about 4.5× the area of MINI-1; the set-top-box enclosure and the one-side I/O layout must be re-checked by the hardware owner.
5 GHz adds EN 301 893 radio testing and DFS behaviour; EU 5150–5350 MHz is indoor-only and its status on board a vessel needs a regulatory check before the uplink may use those channels.
SDIO is unavailable on C5 chip revisions v0.0/v0.1; purchasing must specify revision ≥ v0.2.
SDIO and USB Serial/JTAG share IO13/IO14 on the carrier; C5 flashing on the Linux boards goes through UART0 + BOOT/EN from Linux (as with the C6 today), to be confirmed.
Module price is an estimate; Air Hub and Mini stay over their cost ceilings, Pro's margin shrinks slightly.

Scope

About 8 product-package files plus 4–5 governance files and tracking. No KiCad files.

Alternatives

C5 on the Mini only (as evaluated on 2026-10-25): keeps the Linux carrier layout; two module families in the line.
Keep C6 everywhere: no layout or 5 GHz certification work, but no 5 GHz uplink.

Annotations

2026-10-28: owner approved WROOM-1-N4 (Air Hub / Pro) and WROOM-1-N8R2 (Mini) on the basis of the wrong "no C5-MINI" statement; implementation paused until the owner confirms the module family again. The hardware session (ybo-c3) proposes MINI-1-N4 for the Linux carrier.
2026-10-28: owner replied "你更新文档"; implementation resumed with the approved WROOM-1 choice. Carrier pins are written as a documentation proposal (module-fixed SDIO/UART0/boot pins) pending the hardware session's schematic. The Air Hub Mini board was regenerated with the C5-WROOM-1-N8R2 by task 20261028-1730 (session ybo-d1), which owns the Mini sections of the reference board page; Mini figures here follow that board ($16.7 electronics, $22.4–27.7 landed).