KiCad Project Analysis Skill

Related Skills

Skill	Purpose
bom	BOM extraction, enrichment, ordering, and export workflows
digikey	Search DigiKey for parts (prototype sourcing)
mouser	Search Mouser for parts (secondary prototype source)
lcsc	Search LCSC for parts (production sourcing, JLCPCB)
element14	Search Newark/Farnell/element14 (international sourcing, reliable datasheets)
jlcpcb	PCB fabrication & assembly ordering
pcbway	Alternative PCB fabrication & assembly
spice	SPICE simulation verification of detected subcircuits
emc	EMC pre-compliance risk analysis — consumes schematic + PCB analyzer output

Handoff guidance: Use this skill to parse schematics/PCBs and extract structured data. Hand off to bom for BOM enrichment, pricing, and ordering. Hand off to digikey/mouser/lcsc/element14 for part searches and datasheet fetching. Hand off to jlcpcb/pcbway for fabrication ordering and DFM rule validation. Always run spice for simulation verification during design reviews when any SPICE simulator is installed (check with which ngspice ltspice xyce). Always run emc for EMC pre-compliance risk analysis during design reviews when both schematic and PCB analysis are available. These are not optional — skipping them leaves value-computation errors and EMC risks undetected.

Before analysis: When the user asks to analyze or review a KiCad project, check whether a datasheets/ directory exists in the project. If not, and DigiKey API keys are available (DIGIKEY_CLIENT_ID), offer to sync datasheets first: "I can download datasheets for your components before analysis — this enables pin-level verification and decoupling validation against manufacturer specs. Want me to sync them?" If the user declines or no API keys are set, proceed without datasheets — the analysis works without them but datasheet verification findings won't be available.

If you see a DS-001 finding in the analyzer output (severity high, detector audit_datasheet_coverage), the review cannot make any verified claim. Stop and either (a) run the datasheet sync via digikey / mouser / lcsc / element14 (whichever has credentials/stock), (b) populate MPNs on the BOM parts, or (c) state explicitly in the report that every pin-level, electrical, and regulator finding is consistency only — do not use the words "verified", "confirmed", or "per datasheet" anywhere. DS-002 (datasheets missing but MPNs set) and DS-003 (partial MPN coverage) are softer variants with the same implication for the parts they cite.

Design Review Contract

When the user asks for a design review, complete report, ready-to-fab assessment, or anything equivalent, do not stop at running one or two analyzers and summarizing their findings. A design review in this skill has a stricter contract:

1. Read the full workflow in this SKILL.md, not just the analyzer command sections.
2. Read references/report-generation.md before writing the report.
3. Run every applicable analyzer for the files present in the project, then say explicitly which ones were and were not run.
4. Perform raw-file and datasheet cross-verification before claiming anything is "verified".
5. Triage likely analyzer false positives before elevating them into blockers.
6. If a required step could not be done, state it as a review gap, not as silent omission.

Treat this as the minimum bar. Analyzer JSON alone is not the final review.

Minimum Review Checklist

For a full design review, explicitly account for each item below in the report:

• datasheets/ present, synced, or verification gap stated
• analyze_schematic.py
• analyze_pcb.py --full
• cross_analysis.py
• analyze_emc.py
• SPICE simulation when any simulator is installed
• analyze_thermal.py when both schematic and PCB JSON exist
• analyze_gerbers.py when fabrication outputs exist
• lifecycle audit when network access and MPN coverage allow it
• prior review / prior run delta check
• raw schematic/PCB spot-verification elevated to full verification for critical parts
• explicit report sections for blockers, verification basis, false positives, and skipped analyses

If an item is not applicable, say why. If it was skipped, say why. If it failed, say how that limits confidence.

Common Review Failure Modes

These are the failure modes this contract is meant to prevent:

• Stopping after schematic + PCB + EMC output and calling it a complete review
• Reporting analyzer findings without checking whether they are expected layout artifacts
• Claiming "verified" without direct datasheet evidence or structured extraction evidence
• Omitting thermal, lifecycle, prior-review delta, or gerber checks without disclosure
• Writing a report that lacks a verdict, blockers table, verification basis, or skipped-analysis notes
• Reading only the first part of this skill and missing the design-review workflow later in the file

PDF Schematic Analysis

This skill also handles PDF schematics — reference designs, dev board schematics, eval board docs, application notes, and datasheet typical-application circuits. Common use cases:

• Analyze a manufacturer's reference design to understand the circuit
• Extract a subcircuit (power supply, USB interface, sensor front-end) to incorporate into your own KiCad design
• Compare a PDF reference design against your own schematic
• Extract a full BOM from a PDF schematic
• Validate component values in a PDF against current datasheets

Workflow: Read the PDF pages visually → identify components and connections → extract structured data → translate to KiCad symbols and nets → validate against datasheets.

For the full methodology — component extraction, notation conventions, net mapping, subcircuit extraction, KiCad translation, and validation — read references/pdf-schematic-extraction.md.

For deep validation of extracted circuits against datasheets (verifying values, checking patterns, detecting errors), use the methodology in references/schematic-analysis.md.

Analysis Scripts

This skill includes Python scripts that extract comprehensive structured JSON from KiCad files in a single pass. Run these first, then reason about the output.

Read analyzer JSON output directly rather than writing ad-hoc extraction scripts. The JSON schema has specific field names (documented below and in references/output-schema.md) that are easy to get wrong in custom code. To extract a specific section: python3 -c "import json; d=json.load(open('file.json')); print(json.dumps(d['key'], indent=2))".

When the JSON surprises you — an AttributeError, unexpected shape, field returning None that "should" have a value — stop and run --schema before writing a second extraction attempt. It prints the exact field names and types for every top-level key:

python3 <skill-path>/scripts/analyze_schematic.py --schema
python3 <skill-path>/scripts/analyze_pcb.py --schema
python3 <skill-path>/scripts/analyze_gerbers.py --schema

JSON field cheat sheet — the most common mistakes when reading analyzer output by hand:

What you want	Correct path and field	Common mistake
Pins on a net	nets[<name>].pins[].component / .pin_number / .pin_name / .pin_type	ref, pin, type, number
Unnamed-net pretty display	nets[<name>].display_name — when set, a Ref.PinName hint for an __unnamed_N net whose only named IC pin tells the story (e.g. __unnamed_36 → U1.VBOOT). Absent means the analyzer couldn't disambiguate.	Ignoring display_name and pasting raw __unnamed_36 into the report
IC pin map	ic_pin_analysis[] is a list of IC entries; each has .reference and .pins[] with .pin_number / .pin_name / .pin_type / .net / .connected_to[]. Scope: type in {ic, connector, crystal, oscillator} only.	Treating it as {ref: {...}} or pins[].number
Transistor pin map	transistor_pin_analysis[] — separate list for type=transistor (MOSFETs, BJTs, FETs), same per-entry shape as ic_pin_analysis[]. Use this for half-bridge / gate-driver pin verification.	Looking inside ic_pin_analysis[] for Q1 — transistors are not there
Detected circuits	Every pattern-matched circuit (power regulators, RC filters, crystal oscillators, bridges, …) lives in findings[] — filter with finding_schema.get_findings(data, Det.POWER_REGULATORS) etc. Do not read from subcircuits[]: that's an IC-neighborhood grouping ({center_ic, ic_value, neighbor_components, …}), not a categorized detection index	Looking for subcircuits.power_regulators, subcircuits.rc_filters, or any subcircuits[type] key — these never existed in v1.3 output
Zone net	pcb.zones[].net is an integer net ID, not a string. Use f"{net!r}" or convert first	f"{net:20s}" — crashes with ValueError: Unknown format code 's' for object of type 'int'
Zone layer	pcb.zones[].layers (plural) is the canonical layer list. zones[].layer (singular) is reserved/None on multi-layer zones — always read .layers.	Reading zones[].layer and getting None
Footprint position	pcb.footprints[].x / .y at top level (no .position wrapper)	footprints[].position.x
Per-pad net info on a footprint	pcb.footprints[].pad_nets{pad_number: {net, pin}} is a dict keyed by pad number. connected_nets[] gives the deduped list of nets touching the footprint.	footprints[].pads[] — that key does not exist in the output
Tracks summary	pcb.tracks is a dict (the Tracks envelope): {segment_count, arc_count, layer_distribution{}, width_distribution{}}. Only --full populates the inner tracks.segments[] and tracks.arcs[] arrays. Segment fields: {x1, y1, x2, y2, width, layer, net} — net is an int id (map via top-level nets / net_name_to_id).	for t in tracks: ... without --full — tracks is the summary dict, not a list; seg.get("x") / seg.get("start") — wrong keys, and .get() defaults turn them into silent-0.0 bugs
Power net routing	pcb.power_net_routing is a list of per-net entries [{net, track_count, total_length_mm, ...}, ...], not a dict keyed by net.	power_net_routing["VCC"] → TypeError
Findings	findings[] flat list — each has rule_id, detector, severity, summary, report_context. Filter with finding_schema.get_findings(data, Det.*) or group_findings(data)	Looking for keyed dicts like signal_analysis.power_regulators[] (pre-v1.3 format, removed)

This prevents format-string bugs and wrong field names. Use f-strings or json.dumps() for output formatting — never %s with non-string types. See references/output-schema.md for the full schema with common extraction patterns.

In all commands below, <skill-path> refers to this skill's base directory (shown at the top of this file when loaded).

Schematic Analyzer

python3 <skill-path>/scripts/analyze_schematic.py <file.kicad_sch> --analysis-dir analysis/
python3 <skill-path>/scripts/analyze_schematic.py <file.kicad_sch> --analysis-dir analysis/ --compact
python3 <skill-path>/scripts/analyze_schematic.py <file.kicad_sch> --output analysis.json  # one-off, no cache

Outputs structured JSON (~60-220KB depending on board complexity) with:

• Components & BOM: inventory with reference, value, footprint, lib_id, type classification, MPN, datasheet; deduplicated BOM with quantities
• Nets: full connectivity map with pin-to-net mapping, wire counts, no-connects
• Detected subcircuits (pattern-matched circuits — all emitted as findings[] entries with matching Det.* detectors; use get_findings(data, Det.POWER_REGULATORS) etc. to fetch):
  • Power regulators — LDO/switching/inverting topology, Vout estimation via datasheet-verified Vref lookup (~60 families) with heuristic fallback and fixed-output suffix parsing, vref_source (lookup/heuristic/fixed_suffix) and vout_net_mismatch fields
  • Voltage dividers, RC/LC filters (cutoff frequency), feedback networks, crystal circuits (load cap analysis, IC pin-based detection)
  • Op-amp circuits (configuration, gain, integrator/compensator), transistor circuits (net-name-aware load classification: motor/heater/fan/solenoid/valve/pump/relay/speaker/buzzer/lamp; FET level shifter topology)
  • Bridge circuits (H-bridge, 3-phase, cross-sheet detection), protection devices (ESD/TVS), current sense, decoupling analysis
  • Domain-specific: RF chains, RF matching networks, BMS, Ethernet (BFS PHY-to-connector tracing), HDMI/DVI interfaces, memory interfaces, key matrices (net-name and topology-based), isolation barriers, addressable LED chains (WS2812/SK6812/APA102), battery chargers (TP4056/MCP73831/BQ2404x), motor drivers (A4988/TMC2209/DRV8301), ESD protection coverage audit, debug interfaces (SWD/JTAG with MCU tracing), power path (load switches/ideal diodes/USB PD controllers), ADC signal conditioning (external ADCs + voltage references with anti-aliasing cross-ref), reset/supervisor circuits (voltage supervisors/watchdogs/RC reset networks), clock distribution (clock generators/PLLs/oscillator output tracing), display/touch interfaces (SSD1306/ILI9341/ST7789/FT6236/GT911), sensor fusion (IMU/environmental/magnetometer with interrupt validation and bus clustering), level shifters (IC-based + discrete BSS138 with supply domain mapping), audio circuits (amplifiers/codecs with I2S/class-D detection), LED driver ICs (PWM/matrix/constant-current), RTC circuits (battery backup/crystal pairing), LED lighting audit (current limiting validation), thermocouple/RTD interfaces (MAX31855/MAX31865), power sequencing validation (power tree/enable chain/PG daisy chain analysis)
• IC pinout analysis: pin-level connectivity, IC function classification (3-tier: library prefix, part number keywords, description fallback)
• Power analysis: PDN impedance (1kHz–1GHz with MLCC parasitics), power budget, power sequencing (EN/PG chains), sleep current audit (resistive paths + regulator Iq with EN detection), voltage derating, inrush estimation
• Design analysis: ERC warnings, power domains, bus detection (I2C/SPI/UART/CAN/RS-485 with COPI/CIPO/SDI/SDO), differential pairs (suffix-pair matching for USB/LVDS/Ethernet/HDMI/MIPI/PCIe/SATA/CAN/RS-485), cross-domain signals (voltage equivalence), BOM optimization, test coverage, assembly complexity, USB compliance
• Quality checks: annotation completeness, label validation, PWR_FLAG audit, footprint filter validation, sourcing audit, property pattern audit, generic transistor symbol detection (flags Q_NPN_/Q_PNP_/Q_NMOS_/Q_PMOS_ symbols with datasheet availability check)
• Structural: MCU alternate pin summary, ground domain classification, bus topology, wire geometry, spatial clustering, pin coverage, hierarchical label validation

Supports modern .kicad_sch (KiCad 6+) and legacy .sch (KiCad 4/5). Hierarchical designs parsed recursively.

Legacy format: For KiCad 5 legacy .sch files, the analyzer parses .lib files (cache libraries and project libs) to populate pin data. Pin-to-net mapping, signal analysis, and subcircuit detection all work when .lib files are available. Coverage is typically 92–100% — components whose .lib files are missing (standard KiCad system libs not in the repo) will lack pin data. Built-in fallbacks cover 40+ common symbols (R, C, L, D, LED, transistors, MOSFETs, crystals, switches, polarized caps, connectors up to 20-pin, resistor packs) with mil-based pin offsets and automatic wire-snap correction for version-mismatched pin positions.

Supplementary Data for Legacy Designs

When analyze_schematic.py returns incomplete data (components with missing pins due to unavailable .lib files), use additional project files to recover full analysis capability. The most valuable source is the .net netlist file, which provides explicit pin-to-net mapping that closes any remaining gaps.

For detailed parsing instructions, data recovery workflows, and a priority matrix of supplementary sources (netlist, cache library, PCB cross-reference, PDF exports), read references/supplementary-data-sources.md.

Verify analyzer output against reality. The analyzer can silently produce plausible-looking but incorrect results — wrong voltage estimates, missing MPNs, wrong pin-to-net mappings. These don't cause script errors; they just produce bad data that flows into your report. In testing across multiple boards, every project had at least one misleading analyzer output. Cross-reference against the raw .kicad_sch file:

1. Component count — grep for (symbol (lib_id blocks, subtract power symbols. Must match analyzer count exactly.
2. Pin-to-net mapping — verify the analyzer's pin-to-net mapping against the raw schematic for each component. Read the symbol block, trace wires/labels to confirm connections. Cross-reference IC pin assignments against the manufacturer's datasheet pin table. This is the highest-value verification step — a wrong pin mapping produces a non-functional board and is invisible to DRC/ERC.
3. Physical correctness (not just consistency) — consistency checks (schematic=PCB=analyzer all agree) are necessary but not sufficient. They only confirm the design is internally coherent — not that it matches the real-world part. The most dangerous case: a transistor symbol encodes a pinout assumption (like Q_NPN_BEC = pin 1=B, 2=E, 3=C) that doesn't match the actual part. Everything passes consistency checks, but the board is wrong. To catch this:
   • For transistors (BJT/MOSFET) in SOT-23, SOT-223, TO-252 and similar packages, the KiCad lib_id suffix encodes a pin ordering assumption. SOT-23 BJTs exist in at least 6 pinout variants (BEC, BCE, EBC, ECB, CBE, CEB); SOT-23 MOSFETs in GDS, GSD, SGD, DSG. If no MPN is specified, there's no way to verify the assumption — flag this as a critical ambiguity.
   • When an MPN is specified, verify the symbol's pin-to-pad assignment against the datasheet's pinout diagram for that specific package.
   • This principle extends beyond transistors — any component where multiple pin orderings exist for the same package (voltage regulators with different pin assignments, connectors with vendor-specific pinouts) needs MPN-level verification.
   • When verification isn't possible, assess plausibility. Not all unverified choices carry equal risk. Some align with strong conventions (the most common SOT-23 NPN pinout is BCE; 2N2222 in SOT-23 is almost always BCE); others go against convention or are genuinely ambiguous (SOT-23 MOSFETs have no dominant standard). When an MPN is missing and you can't verify, use domain knowledge — typical pinouts for that device type and package, manufacturer conventions, what the majority of parts in that category do — to assess whether the assumed pinout is likely correct, unusual, or a coin flip. Report the confidence level: "matches the most common convention" is different from "could go either way." This same reasoning applies to passive values (is 4.7kΩ a typical pull-up value for this bus?), circuit topologies (is this a standard application circuit?), and component selection (is this part commonly used for this purpose?).
4. Net trace — trace power rails and critical signal nets end-to-end through wires/labels. Verify the analyzer's pin list is complete for each net.
5. Regulator Vout — check the vref_source field. "lookup" means datasheet-verified (~60 families); "heuristic" means it's a guess that needs manual verification. The vout_net_mismatch field flags estimated Vout differing >15% from the output rail name voltage.
6. Hierarchical connectivity — on multi-sheet designs, verify sub-sheet connections are reflected in the net data.

See references/schematic-analysis.md Step 2 for the full verification checklist. If the script fails or returns unexpected results, see references/manual-schematic-parsing.md for the complete fallback methodology.

PCB Layout Analyzer

python3 <skill-path>/scripts/analyze_pcb.py <file.kicad_pcb> --analysis-dir analysis/
python3 <skill-path>/scripts/analyze_pcb.py <file.kicad_pcb> --analysis-dir analysis/ --proximity  # add crosstalk analysis
python3 <skill-path>/scripts/analyze_pcb.py <file.kicad_pcb> --output pcb.json --schematic analysis/schematic.json  # one-off; cross-ref + power-rail auto-detect

Outputs structured JSON (~50-300KB depending on board complexity) with:

• Core: footprint inventory (pads, courtyards, net assignments, extended attrs, schematic cross-reference), track/via statistics, zone summaries, board outline/dimensions, routing completeness
• Zones & copper presence: zone outline vs filled polygon bounding boxes, fill ratio, cross-layer copper presence at every pad (which components have zone copper on the opposite layer and which don't), same-layer foreign zone detection
• Via analysis: type breakdown (through/blind/micro), annular ring checks, via-in-pad detection, BGA/QFN fanout patterns, current capacity, stitching via identification, tenting
• Signal integrity: per-net trace length, layer transition tracking (ground return paths), trace proximity/crosstalk (with --proximity)
• Power & thermal: current capacity per net, power net routing summary, ground domain identification (AGND/DGND), zone stitching via density, thermal pad detection and via counting
• Manufacturing: placement analysis (courtyard overlaps, edge clearance), decoupling cap distances, DFM scoring (JLCPCB standard/advanced tier), tombstoning risk (0201/0402 thermal asymmetry), thermal pad via adequacy, silkscreen documentation audit

Add --full to include individual track/via coordinates, per-segment trace impedance (microstrip Z0 from stackup), pad-to-pad routed distances, return path continuity analysis, and via stub lengths. The --full output feeds the spice skill's parasitic extraction (extract_parasitics.py) for PCB-aware simulation. Supports KiCad 5 legacy format.

Zone fills must be current. The copper presence analysis uses KiCad's filled polygon data, which is computed when the user runs Edit → Fill All Zones (shortcut B) and stored in the .kicad_pcb file. If the board was modified after the last fill, the filled polygon data may be stale and the copper presence results will be inaccurate. When reviewing copper presence data, note whether the fill_ratio seems reasonable — a zone with 0 filled area or is_filled: false likely hasn't been filled.

Zone outline ≠ actual copper. The zone outline_bbox is the user-drawn boundary; filled_bbox is where copper actually exists after clearances, keepouts, and priority cuts. The copper_presence section shows which components have zone copper on the opposite layer — use this for capacitive touch pad isolation, antenna keep-out, and thermal analysis instead of inferring copper presence from zone outlines.

Copper-sensitive components need deeper checks. For capacitive touch pads and antennas, confirming "no opposite-layer copper" is necessary but not sufficient. The copper absence could be accidental — one zone refill after a routing change could add copper and kill touch sensitivity or detune the antenna. Check for explicit keepout zones (rule areas) that enforce the copper-free area as a DRC rule. Also measure same-layer GND clearance around touch pads and compare against the controller's app note minimum. For touch pads, compare trace lengths across all pads — significant asymmetry shifts baseline readings per channel. Report physical details (pad size, position, clearance, trace width/length) for all copper-sensitive components. See references/pcb-layout-analysis.md → Copper-Sensitive Components for the full checklist.