rpicarrierboard/PORT_STATUS.md

CM5 Carrier Port — Status & Handoff

Handoff doc for whoever (human or LLM) continues this work. Read this first, then .claude/skills/kicad-port/SKILL.md (the mandatory workflow/verify-loop), then CM5_Carrier_Design.md (frozen rev-A spec).

▶ RESUME HERE (session handoff, 2026-07-01)

State: branch port/strip-phase. Sheets in carrier/: root CM5IO, CM5_GPIO, CM5_HighSpeed (reference, stripped), M2_Ekey (E-key, done), Power (stages 1–3 done). Baseline anchor: analysis/baseline/carrier_stripped.json.

Done: strip phase (microSD/HDMI/MIPI/PCIe-M2); M.2 E-key sheet (PCIe ×1 to CM5); Power stage 1 (LM74700 ideal-diode input protection → VIN_PROT); Power stage 2 (LM61460-Q1 15→+5v 5 A sync buck, SPICE-verified 5.02 V); Power stage 3 (LM61460-Q1 15→+3V3_RF 4 A, SPICE-verified 3.32 V; EN ← CM5 PCIE_PWR_EN/106 + 100k pull-down like reference R14; E-key temp PWR_FLAG removed — buck is the sole +3V3_RF driver). Current whole-design ERC = 133 (all pre-existing types; a good edit adds zero new).

NEXT ACTION → Power Stage 4: U_BUCK33A 15→+3V3_AUX ~1 A. Candidate part TPS54202 (28 V sync) — datasheet-verify first (KiCad has Regulator_Switching:TPS54202DDC). One check that MUST pass: the SMBJ18A clamp (~29 V at rated Ipp) vs the part's VIN abs-max — if the datasheet says <30 V abs-max, pick a 36 V-class sync part instead (LMR51430/TPS54360-class) or justify why the surge case is acceptable. FB divider per that part's VREF; SPICE-verify. +3V3_AUX is a NEW net → global label. Then the GPS + PPS sheet, then power-budget review.

How to build/verify (every change):

• Sheets are generated wholesale — edit tools/build_ekey.py / tools/build_power.py, then python3 tools/build_power.py --apply. Custom IC symbols go in carrier/CM5IO.kicad_sym (bare name) AND embed in the sheet as CM5IO:<name> — else ERC lib_symbol_issues.
• Verify loop (judge by the integrated root run, not standalone sub-sheets): kicad-cli sch erc --format json -o /tmp/e.json carrier/CM5IO.kicad_sch (track delta vs 133, zero new types) → analyze_schematic.py carrier/CM5IO.kicad_sch + diff_analysis.py analysis/baseline/carrier_stripped.json … (zero regressions) → for bucks, simulate_subcircuits.py.
• Gotchas (full list in memory port-progress): grid-snap all coords to 1.27 mm or labels don't bind; PWR_FLAG/GND must sit on a real pin coord; pre-existing +5v is hierarchical (not global); type feedback pins passive; connector/module pin types may need remodeling for cross-part ERC.

What this repo is

Two intertwined goals:

1. Improve Claude's EDA tooling — the kicad-happy skill suite (kicad, datasheets, spice, …), wired in as Claude Code skills via ~/.claude/skills/{kicad,datasheets,spice} -> kicad-happy/skills/* symlinks. The toolkit clones (kicad-happy/, kicad-claude-toolkit/, MCP-KiCad/) are gitignored — re-clone if missing.
2. Port the Raspberry Pi CM5IO reference into a custom CM5 carrier board — the real test bed (PTP/timing instrumentation node: 15V→5V front end, GbE magjack, M.2 E-key Wi-Fi (AW7915/MT7915), 2×USB-A, USB-C programming, RTC, GPS-PPS distribution).

Method is diff-from-reference: refs/ holds the untouched CM5IO reference; carrier/ is the working copy. Every edit is verified against analysis/baseline/cm5io.json.

Environment / tooling state (macOS, Homebrew)

• kicad-cli ✅ (/opt/homebrew/bin/kicad-cli) — ERC + netlist export
• poppler ✅ (pdftotext) — datasheet page selection
• ngspice ✅ — spice skill; full verify loop validated on the reference (8 subcircuits pass)
• Python ≥3.10 (Homebrew 3.14)

The verify loop (run after EVERY schematic edit)

SCH=carrier/CM5IO.kicad_sch ; KSCR=~/.claude/skills/kicad/scripts
kicad-cli sch erc --exit-code-violations --format json -o /tmp/erc.json "$SCH"   # hard gate
python3 $KSCR/analyze_schematic.py "$SCH" -o /tmp/head.json                       # structural
python3 $KSCR/diff_analysis.py analysis/baseline/cm5io.json /tmp/head.json --text # vs baseline

• Track the ERC DELTA, not the absolute — the reference already has 182 pre-existing violations (mostly unconnected_wire_endpoint). A good edit introduces zero new types.
• The analyzer diff is the semantic gate (names broken design intent); ERC is the hygiene gate.
• For kept-block integrity, also diff kicad-cli sch export netlist before/after — it caught a mis-inventoried part (see R8 below).

Datasheet extraction (done)

CM5 module extracted to datasheets/extracted/SC1466_43a9ec.json (200 pins, score 8.7/10, queryable via ~/.claude/skills/datasheets/scripts/datasheet_features.py). Drove the NC pin lists for every strip (e.g. HDMI Module1 pins = all pins whose datasheet name starts HDMI).

The strip tool: tools/retire_block.py

General block-retirement for these s-expr sheets. Capabilities:

• excise symbols by Reference; retire nets by name-glob (all label types: local / hierarchical / global)
• anchor-aware wire removal (union-find): removes a wire only if its connected component reaches no kept anchor (kept non-power pin or kept label) AND is seeded by this edit — so shared nets survive and pre-existing dangles are untouched
• place (no_connect) on exposed Module1 pins (pin coords via a validated transform abs=(px+rot(lx,ly).x, py-rot(lx,ly).y), rot0/no-mirror; refuses other orientations)
• clean orphaned power flags, dangling NCs, orphaned labels
• --sheet-ports NAME,... removes root-sheet hierarchical pins + connecting wires

Usage: python3 tools/retire_block.py <sheet> --symbols J7,U18 --nets 'SD_*' --nc-pins 57,61 [--sheet-ports ...] [--apply] (dry-run without --apply).

Known gap (next improvement): does NOT auto-prune orphaned power-label/wire stubs left after a connector is removed (e.g. leftover +3.3v/HDMI_5v labels). Those were cleaned manually — see git history.

Strip phase — DONE (microSD + HDMI + MIPI + PCIe-M2), ERC 182 → 133, 0 new violations, 0 regressions

Block	Sheet(s)	Command(s) (run with --apply)
microSD	CM5_GPIO	--symbols J7,U18,C5 --nets 'SD_*' --nc-pins 57,61,62,63,67,69,75
HDMI	CM5_HighSpeed	--symbols J22,J10 --nets 'HDMI0_*,HDMI1_*,HDMI_5v' --nc-pins 143,145,146,147,148,149,151,152,153,154,158,160,164,166,170,172,176,178,182,184,188,190,199,200
MIPI/camera	CM5_HighSpeed, CM5_GPIO, CM5IO(root)	(1) HighSpeed --symbols J5,J16 --nets 'DPHY0_*,DPHY1_*,SCL1,SDA1' --nc-pins 115,117,121,123,127,129,133,135,139,141,175,177,181,183,187,189,193,194,195,196 (2) GPIO --nc-pins 80,82,97,100 (3) root --sheet-ports SCL0,SDA0,CAM_GPIO0,CAM_GPIO1 (4) HighSpeed --symbols R8 --nets 'SCL0,SDA0' (5) manual: remove 3 orphaned +3.3v labels + 2 wire stubs
PCIe-M2 (M-key/NVMe)	CM5_HighSpeed, CM5IO(root), .kicad_pro	(1) HighSpeed --nets 'PCIE_*' --nc-pins 102,104,106,109,110,112,116,118,122,124 (2) root --drop-sheet PCIe-M2.kicad_sch (3) root --sheet-ports PCIE_CLK_P,PCIE_CLK_N,PCIE_TX_P,PCIE_TX_N,PCIE_nRST,PCIE_RX_P,PCIE_RX_N,PCIE_nCLKREQ,PCIE_PWR_EN,PCIE_nWAKE (strip dangling HighSpeed sheet-symbol pins) (4) git rm carrier/PCIe-M2.kicad_sch (5) manual: remove PCIe-M2 entry from .kicad_pro sheets array + its ERC exclusion. Design confirmed: 1× M.2 E-key (Wi-Fi) only, 0× M-key SSD — the single CM5 PCIe ×1 lane is reserved for the E-key; the freed PCIE_* lanes (now NC on Module1 unit 2) will be rewired to the fresh E-key sheet in the add phase.

retire_block.py gained --drop-sheet FILE: removes the whole (sheet …) block by Sheetfile + its sheet_instances path (run on the parent sheet). .kicad_pro sheets-array + ERC-exclusion cleanup is still manual (next tool gap).

Notes that bit us (don't re-learn the hard way):

• MIPI lanes are labeled DPHY0_*/DPHY1_*, NOT MIPI*. The connectors J5/J16 are camera FFCs bundling DPHY + cross-sheet I2C0 (SCL0/SDA0) + CAM_GPIO0/1 — a 3-sheet hierarchical block.
• R8 is a camera pull-up, not USB (the Explore-agent inventory was wrong). Confirmed via kicad-cli sch export netlist (R8.2 → J16.17). Always verify inventory against the netlist.
• SCL0/SDA0 (I2C0) are camera-only 2-node nets (netlist-proven). NC'd to reserve I2C0 for a future external I2C RTC (CM5's own RTC is on-module via VBAT). If you add an external RTC, wire it here.

Next steps

1. Drop the PCIe-M2 sheet entirely DONE (see strip table). Confirmed E-key-only (no M-key SSD).
2. Re-baseline DONE — analysis/baseline/carrier_stripped.json is the add-phase diff anchor.
3. M.2 E-key sheet ✅ DONE (carrier/M2_Ekey.kicad_sch, generated by tools/build_ekey.py). J_E = KiCad Connector:Bus_M.2_Socket_E, fp Connector_PCBEdge:M.2_2230-xx-E. PCIe link-0 wired to the 9 freed CM5 pins via global labels (PCIE_TX/RX/CLK ±, nRST, nCLKREQ, nWAKE — netlist-confirmed J_E↔Module1); +3V3_RF (4 pins) + 10µF∥2×0.1µF decoupling + temp PWR_FLAG; 11 GND; W_DISABLE1/2 10k pull-ups to +3V3_RF; ~41 NC (USB/BT, PCM/I2S, SDIO, UART, COEX, I2C, link-1). RX not coupled on carrier (card-side per M.2; BOM C_PCIE removed). Verify: ERC 133→133 (zero new); analyzer diff +7 added, 0 regressions. Connector-symbol pin types remodeled for cross-connector ERC: lines CM5 drives → passive; lines the card drives into CM5 inputs (RX pair + CLKREQ#/WAKE#) → output. Open items (review/next): (a) CM5 PCIE_PWR_EN (pin 106) still NC — wire to the +3V3_RF buck EN in the power sheet; (b) the temp PWR_FLAG on +3V3_RF must be REMOVED once the buck drives it (else dual-driver ERC); (c) optionally route WIFI_DISABLE# to a CM5 GPIO for SW radio control; (d) analyzer CG-AUD 5:1 sig/gnd on J_E is inherent to the M.2 connector (INFO, not fixable). New tool: tools/build_ekey.py (place connector + auto-NC + labels).
4. Power sheet (carrier/Power.kicad_sch, generated by tools/build_power.py) — staged, sync + datasheet-built parts (user choice). Spec rating fix: the spec's buck candidates miss its own ≥20V-Vin rule (TPS54424=17V, TPS54560=async) — selecting synchronous ≥30V parts instead (LM61460-class 6A for +5V & +3V3_RF/4A; TPS54202 28V for +3V3_AUX), each verified vs datasheet before commit.
   • Stage 1 — input protection ✅ DONE. J_PWR(15V) → D_REV LM74700-Q1 ideal-diode + Q_REV N-FET (reverse-polarity/-current) → VIN_PROT; SMBJ18A TVS + 100µF/25V ∥ 10µF/50V bulk; C_VCAP charge-pump cap. Netlist-verified topology; ERC 133→133 (zero new); analyzer 0 regressions. Confirm vs LM74700-Q1 datasheet: C_VCAP value, EN-to-+15V_IN, FET pick (Vds≥30V, SOA/inrush) + optional gate R.
   • Stage 2 — U_BUCK5 15→+5v 5A ✅ DONE. LM61460-Q1 (6A, 42V absmax sync; custom symbol built from the datasheet → carrier/CM5IO.kicad_sym as CM5IO:LM61460-Q1, fp Package_SO:Texas_HTSSOP-14-1EP…ThermalVias). VREF=1.0V → FB divider R_FBT5 40.2k / R_FBB5 10.0k = 5.02V (SPICE-confirmed vfb=1.0V). L5 4.7µH, Cout 2×47µF/16V, Cin 2×10µF/50V, Cboot 100n+Rboot 4.7Ω, RT 31.6k(~400kHz), BIAS→+5v, EN→VIN_PROT, PGOOD 100k→+5v. +5v kept HIERARCHICAL (pre-existing carrier net; global would collide same_local_global_label) — Power sheet exposes a +5v sheet pin, tied into the root +5v net; netlist-verified it drives Module1 + GPIO + USB. ERC 133→133 (zero new); analyzer +32 added 0 regressions; SPICE 12/13 pass, 1 benign warn (L5/Cboot mis-detected as LC filter). Confirm vs datasheet: RT freq, L sat ≥7A, EP=pad15, optional EN UVLO divider.
   • Stage 3 — U_BUCK33R 15→+3V3_RF 4A ✅ DONE. Second LM61460-Q1 (shared BOM with stage 2: L 4.7µH/7A ripple ~1.3A=33%, Cin 2×10µ/50V, Cout 2×47µ/16V, RT 31.6k ~420kHz, Cboot 100n+Rboot 4.7). FB divider R_FBT33 23.2k / R_FBB33 10.0k = 3.32V (SPICE: vfb 0.994V, inrush settles 3.32V). BIAS→+3V3_RF (datasheet: valid ≥3.1V, auto-falls back to VIN below). EN ← CM5 PCIE_PWR_EN (Module1 pin 106: NC swapped for a global label on CM5_HighSpeed) + R_EN33 100k pull-down (mirrors reference R14 — netlist-verified Module1.106 + U_BUCK33R.7 + R_EN33.1) so the Wi-Fi rail is OFF until the CM5 asserts it. E-key temp #FLG33RF PWR_FLAG removed (build_ekey); the buck's PWR_FLAG on L33.2 is now the sole +3V3_RF driver — netlist shows buck + all 4 J_E power pins + pull-ups + decoupling on one net. Verify: ERC 133→133 zero new; analyzer +49 added 0 regressions; SPICE 17 pass / 2 benign warn (the L/C_BOOT "LC filter" mis-detect, once per buck) / 0 fail. (Note: kicad-cli netlist export prints a pre-existing "annotation errors" warning — un-numbered generated refdeses like J_E/J_PWR; present at fd627f5 too, cosmetic.)
   • Stage 4 U_BUCK33A 15→3.3V ~1A → +3V3_AUX. SPICE-validate the feedback divider (see NEXT ACTION above for the part-selection gate).
5. GPS + PPS distribution: GPS connector (PPS+UART+3V3+GND); PPS → TVS → Schmitt (LVC1G17) → fan-out: CM5 Ethernet_SYNC_OUT (J2 pin-6 net, 3.3V, no translator) + 2 header taps. SPICE/timing check.

Out-of-repo notes

Richer running notes live in this machine's Claude memory: ~/.claude/projects/-Users-noise-Documents-obsidian-rpiboard/memory/ (project-cm5-eda, port-progress, eda-tooling-gaps, tooling-installs-cm5). This doc is the portable subset.