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KiCad Routing Tools

A fast Rust-accelerated A* autorouter for KiCad PCB files. Compatible with KiCad 9 and KiCad 10. Available as both a KiCad Plugin with full GUI and a Command-Line Interface for scripting and automation.

Features

Grid-based A* pathfinding with Rust acceleration (~10x faster than Python)
Octilinear routing - Horizontal, vertical, and 45-degree diagonal moves
Multi-layer routing with automatic via insertion
Differential pair routing with pose-based A* and Dubins path heuristic for orientation-aware centerline routing
Rip-up and reroute - When routing fails, automatically rips up blocking routes and retries with progressive N+1 strategy (tries 1 blocker, then 2, up to configurable max). Re-analyzes blocking tracks after each failure for better recovery. Also triggers rip-up when quick probes detect blocking early, before attempting full routes. See Rip-Up and Reroute for details
Ripped route corridor avoidance - When a net is ripped up, soft penalties are applied to its former corridor. This encourages the current route to avoid that area, increasing the chance the ripped net can be successfully re-routed later.
Blocking analysis - Shows which previously-routed nets are blocking when routes fail
Stub layer switching - Optimization that moves stubs to different layers to avoid vias when source/target are on different layers. Works for both differential pairs and single-ended nets. Finds compatible swap pairs (two nets that can exchange layers to help each other) or moves stubs solo when safe. Tries multiple swap options (source/source, target/target, source/target, target/source) to find valid combinations. Validates that stub endpoints won't be too close to other stubs on the destination layer.

Comments

KiCad Routing Tools

Features

Grid-based A* pathfinding with Rust acceleration (~10x faster than Python)

Octilinear routing - Horizontal, vertical, and 45-degree diagonal moves

Multi-layer routing with automatic via insertion

Differential pair routing with pose-based A* and Dubins path heuristic for orientation-aware centerline routing

Rip-up and reroute - When routing fails, automatically rips up blocking routes and retries with progressive N+1 strategy (tries 1 blocker, then 2, up to configurable max). Re-analyzes blocking tracks after each failure for better recovery. Also triggers rip-up when quick probes detect blocking early, before attempting full routes. See Rip-Up and Reroute for details

Ripped route corridor avoidance - When a net is ripped up, soft penalties are applied to its former corridor. This encourages the current route to avoid that area, increasing the chance the ripped net can be successfully re-routed later.

Blocking analysis - Shows which previously-routed nets are blocking when routes fail

Stub layer switching - Optimization that moves stubs to different layers to avoid vias when source/target are on different layers. Works for both differential pairs and single-ended nets. Finds compatible swap pairs (two nets that can exchange layers to help each other) or moves stubs solo when safe. Tries multiple swap options (source/source, target/target, source/target, target/source) to find valid combinations. Validates that stub endpoints won't be too close to other stubs on the destination layer.

Pattern	Description
`*`	All nets
`DATA`	Nets containing "DATA"
`/*`	Nets starting with "/" (hierarchical)
`Net-(U1-*)`	Nets matching "Net-(U1-...)"
`!GND`	Exclude net named "GND"
`!VCC`	Exclude nets containing "VCC"
`"*" "!GND" "!VCC"`	All nets except GND and VCC

Document	Description
Routing Architecture	Module structure, obstacle maps, A* algorithm
Python API	Using the modules as a library: parser, writer, modification, config, net analysis, impedance — with runnable examples
Configuration	Command-line options, GridRouteConfig parameters
Differential Pairs	P/N pairing, polarity swaps, via handling
Net Ordering	MPS algorithm, inside-out ordering, strategy comparison
Rip-Up and Reroute	Blocking analysis, progressive N+1 escalation, reroute loop
Length Matching	Trombone meanders, via barrel lengths, DDR auto-grouping, time matching
Bus Routing	Bus detection, middle-out ordering, neighbor attraction
Guide Corridor	User-layer guide paths, waypoints, best-effort following
Power/Ground Planes	Copper zones with automatic via placement
Utilities	DRC checker, connectivity checker, fanout generators, layer switcher
BGA Fanout	BGA escape routing generator
QFN Fanout	QFN/QFP escape routing generator
Rust Router	Building and using the Rust A* module
Visualizer	Real-time A* visualization with PyGame
Power Net Analysis	Power net detection, AI analysis, track width guidelines
Claude Skills	All eight AI skills: routing plans, power/high-speed/diff-pair analysis, stackup, plane mappings, failure diagnosis, board review
Placement	Placement optimization for routability
Integration Tests	Test scripts and performance benchmarks
Release Pipeline	How to tag a release and submit it to the KiCad PCM (maintainers)

KiCadRoutingTools/ ├── place_optimize.py # Main CLI - placement optimization (quench) ├── place_route_loop.py # Main CLI - router-in-the-loop placement repair ├── route.py # Main CLI - single-ended routing ├── route_diff.py # Main CLI - differential pair routing ├── route_planes.py # Main CLI - power/ground plane via connections ├── route_disconnected_planes.py # CLI - repair disconnected plane regions ├── plane_io.py # Plane I/O utilities (zone extraction, output writing) ├── plane_obstacle_builder.py # Obstacle map building for plane via placement ├── plane_blocker_detection.py # Blocker detection and rip-up for plane vias ├── plane_zone_geometry.py # Voronoi zone computation for multi-net layers ├── plane_resistance.py # Plane resistance and current capacity calculations ├── plane_region_connector.py # Detect and route between disconnected plane regions ├── routing_config.py # GridRouteConfig, GridCoord, DiffPair classes ├── routing_defaults.py # Default routing parameter values ├── routing_exceptions.py # Routing exception classes ├── routing_state.py # RoutingState class - tracks routing progress ├── routing_context.py # Helper functions for obstacle building ├── routing_common.py # Shared utilities for route.py and route_diff.py ├── routing_utils.py # Shared utilities (pos_key, etc.) ├── obstacle_map.py # Obstacle map building functions ├── obstacle_cache.py # Net obstacle caching for incremental builds ├── obstacle_costs.py # Stub/track proximity cost calculations ├── bresenham_utils.py # Bresenham line-walking utilities for grid operations │ ├── diff_pair_loop.py # Differential pair routing loop ├── single_ended_loop.py # Single-ended routing loop ├── reroute_loop.py # Reroute queue processing ├── phase3_routing.py # Phase 3 multi-point tap routing ├── diff_pair_routing.py # Diff pair A* routing implementation ├── single_ended_routing.py # Single-ended A* routing implementation │ ├── net_ordering.py # MPS, inside-out, and original ordering ├── net_queries.py # Net queries (diff pairs, MPS, endpoints) ├── connectivity.py # Stub endpoints, connected groups ├── layer_swap_optimization.py # Upfront layer swap optimization ├── layer_swap_fallback.py # Fallback layer swap on failure ├── stub_layer_switching.py # Stub layer swap utilities ├── mps_layer_swap.py # MPS-aware layer swap for crossing conflicts ├── polarity_swap.py # P/N polarity swap handling ├── target_swap.py # Target assignment optimization ├── rip_up_reroute.py # Rip-up and reroute logic ├── blocking_analysis.py # Analyze blocking nets ├── length_matching.py # Length matching with trombone meanders │ ├── kicad_parser.py # KiCad .kicad_pcb file parser ├── kicad_writer.py # KiCad S-expression generator ├── output_writer.py # Route output and swap application ├── pcb_modification.py # Add/remove routes from PCB data ├── schematic_updater.py # Update .kicad_sch files with pad swaps ├── chip_boundary.py # Chip boundary detection ├── geometry_utils.py # Shared geometry calculations ├── impedance.py # Impedance calculation (microstrip/stripline formulas) ├── memory_debug.py # Memory usage statistics │ ├── check_drc.py # DRC violation checker ├── check_connected.py # Connectivity checker (with T-junction detection) ├── check_orphan_stubs.py # Orphan stub detector ├── bga_fanout.py # BGA fanout CLI wrapper ├── bga_fanout/ # BGA fanout package │ ├── __init__.py # Main fanout logic and public API │ ├── types.py # Track, BGAGrid, FanoutRoute, Channel, DiffPairPads │ ├── escape.py # Escape channel finding and assignment │ ├── reroute.py # Collision resolution and rerouting │ ├── layer_balance.py # Layer rebalancing for even distribution │ ├── layer_assignment.py # Layer assignment for collision avoidance │ ├── tracks.py # Track generation and collision detection │ ├── geometry.py # 45° stub and jog calculations │ ├── collision.py # Low-level collision detection utilities │ ├── grid.py # BGA grid analysis │ ├── diff_pair.py # Differential pair detection │ └── constants.py # Configuration constants ├── qfn_fanout.py # QFN/QFP fanout CLI wrapper ├── qfn_fanout/ # QFN/QFP fanout package │ ├── __init__.py # Main fanout logic and public API │ ├── layout.py # Layout analysis functions │ ├── geometry.py # Stub position calculations │ └── types.py # QFNLayout, PadInfo, FanoutStub ├── list_nets.py # List nets on a component ├── build_router.py # Rust module build script (--clean to remove artifacts) ├── startup_checks.py # Startup checks (Python deps, Rust library version) │ ├── tests/ # Integration tests │ ├── test_fanout_and_route.py # Full integration test (fanout + route) │ ├── test_kit_route.py # Pad-to-pad routing test (no fanout) │ ├── test_flat_hierarchy.py # 2-layer board with GND plane test │ ├── test_interf_u.py # 2-layer board with non-rectangular outline test │ ├── test_sonde_u.py # Wide track routing test │ └── run_utils.py # Shared test utilities │ ├── rust_router/ # Rust A* implementation ├── pygame_visualizer/ # Real-time visualization ├── kicad_routing_plugin/ # KiCad ActionPlugin │ ├── action_plugin.py # ActionPlugin entry point │ ├── swig_gui.py # Main routing dialog (Basic/Advanced tabs) │ ├── differential_gui.py # Differential pair routing tab │ ├── fanout_gui.py # BGA/QFN fanout tab and net selection panel │ ├── planes_gui.py # Power/ground planes tab │ ├── about_tab.py # About tab with version info │ ├── gui_utils.py # Shared GUI utilities │ └── settings_persistence.py # Save/restore dialog settings between sessions ├── placement/ # Component placement │ ├── engine.py # Core placement algorithm │ ├── parser.py # Courtyard boundary extraction │ ├── writer.py # Footprint position modification │ └── utility.py # Shared placement utilities ├── install_plugin.py # Plugin installer script ├── docs/ # Documentation └── .claude/skills/ # Claude Code skills ├── analyze-power-nets/ # AI-powered power net analysis skill ├── find-high-speed-nets/ # AI-powered high-speed net identification skill ├── plan-pcb-routing/ # AI-powered routing plan generation skill (orchestrates the others) ├── identify-diff-pairs/ # Datasheet-based diff pair detection skill ├── recommend-stackup/ # Stackup review/recommendation skill ├── diagnose-routing-failures/ # Failure root-cause and retry skill ├── review-routed-board/ # Post-route QA and sign-off skill └── stress-test-router/ # Batch stress-test on real-world boards + issue filing (dev/QA)

Module	Purpose
`route.py`	CLI for single-ended routing
`route_diff.py`	CLI for differential pair routing
`route_planes.py`	CLI for power/ground plane via connections
`route_disconnected_planes.py`	CLI for repairing disconnected plane regions
`routing_config.py`	Configuration dataclasses (`GridRouteConfig`, `GridCoord`, `DiffPair`)
`routing_state.py`	`RoutingState` class tracking progress, results, and PCB modifications
`routing_context.py`	Helper functions for building obstacles and recording success
`routing_common.py`	Shared utilities for route.py and route_diff.py (BGA zones, net resolution, length matching)
`routing_utils.py`	Shared utilities (`build_layer_map`, `iter_pad_blocked_cells`)
`obstacle_map.py`	Obstacle map building from PCB data
`obstacle_cache.py`	Net obstacle caching for incremental obstacle map builds
`obstacle_costs.py`	Stub and track proximity cost calculations
`bresenham_utils.py`	Bresenham line-walking utilities for grid-based segment operations
`geometry_utils.py`	Shared geometry calculations (point-to-segment distance, segment intersection, UnionFind)
`routing_constants.py`	Shared constants (default layer stack, power net patterns, tolerances)
`terminal_colors.py`	ANSI color codes for terminal output

Module	Purpose
`diff_pair_loop.py`	Main loop for routing differential pairs
`single_ended_loop.py`	Main loop for routing single-ended nets
`reroute_loop.py`	Processes reroute queue for failed routes
`phase3_routing.py`	Phase 3 multi-point tap routing (connects remaining pads after length matching)
`diff_pair_routing.py`	Differential pair A* with centerline + offset and GND vias
`single_ended_routing.py`	Single-ended net A* routing

Module	Purpose
`net_ordering.py`	MPS, inside-out, and original net ordering strategies
`net_queries.py`	Net queries (diff pair detection, MPS ordering, power net detection, chip pad positions)
`connectivity.py`	Stub endpoints, connected groups, multi-point net detection

Module	Purpose
`layer_swap_optimization.py`	Upfront layer swap optimization before routing
`layer_swap_fallback.py`	Try layer swap when route fails
`stub_layer_switching.py`	Low-level stub layer swap utilities
`mps_layer_swap.py`	MPS-aware layer swap for crossing conflicts
`polarity_swap.py`	P/N polarity swap for differential pairs
`target_swap.py`	Hungarian algorithm for optimal target assignment
`rip_up_reroute.py`	Rip-up blocking routes and retry
`blocking_analysis.py`	Analyze which nets are blocking
`length_matching.py`	Length matching with trombone-style meanders

Module	Purpose
`kicad_parser.py`	KiCad .kicad_pcb file parser (extracts stackup, footprint values, pintypes)
`kicad_writer.py`	KiCad S-expression generator
`output_writer.py`	Write routed output with swaps and debug geometry
`pcb_modification.py`	Add/remove routes from PCB data structure
`schematic_updater.py`	Update .kicad_sch files with pad swaps from routing
`impedance.py`	Impedance calculations (microstrip/stripline, width from target Z)
`memory_debug.py`	Memory usage statistics and debugging

Stage	Nets	Time	Iterations
FTDI single-ended	47/47	8.6s	319K
LVDS diff pairs (batch 1)	28/28	29.7s	10.2M
LVDS diff pairs (batch 2)	28/28	28.0s	12.0M
DDR diff pairs	5/5	0.3s	25K
DDR single-ended	51/51	6.2s	565K

python route.py kicad_files/input.kicad_pcb [output.kicad_pcb] [OPTIONS] # Output options (default: input_routed.kicad_pcb) --overwrite, -O # Overwrite input file instead of creating _routed copy # Net selection (default: "*" = all nets) --nets "pattern" ... # Net names or wildcard patterns to route # Supports exclusion: --nets "*" "!GND" "!VCC" = all except GND/VCC --component U1 # Route all nets on U1 (auto-excludes GND/VCC/VDD/unconnected unless --nets given) # Geometry --track-width 0.3 # Track width (mm), ignored if --impedance specified --impedance 50 # Target single-ended impedance (ohms), calculates width per layer from stackup --clearance 0.25 # Track clearance (mm) --via-size 0.5 # Via diameter (mm) --via-drill 0.3 # Via drill (mm) # Power net routing (wider tracks for power/ground) --power-nets "*GND*" "*VCC*" # Glob patterns for power nets --power-nets-widths 0.4 0.5 # Widths in mm for each pattern (must match --power-nets length) --neckdown-length 2.5 # Narrow track length (mm) from the pads when a failed wide power # route is retried at the default width (neck-down) --neckdown-taper-length 0.5 # Narrow-to-wide width taper length in mm (0 = abrupt) --no-power-tap-neckdown # Disable the neck-down retry of failed wide power routes # Algorithm --grid-step 0.1 # Grid resolution (mm) --via-cost 50 # Via penalty in 0.1mm grid steps (50 = 5mm of path; all cost knobs # are mm-calibrated, so behavior is independent of --grid-step) --max-iterations 200000 # A* iteration limit --max-probe-iterations 5000 # Quick probe per direction to detect stuck routes --heuristic-weight 1.9 # A* greediness (>1 = faster) --proximity-heuristic-factor 0.02 # Proximity cost estimate (only applied when endpoints in zones, diff pairs use 1/10th) --turn-cost 1000 # Penalty for direction changes (straighter paths) --direction-preference-cost 50 # Penalty for non-preferred layer direction (0=disabled) # Alternates H/V: F.Cu=horizontal, In1.Cu=vertical, etc. --max-ripup 3 # Max blockers to rip up at once (1-N progressive) --routing-clearance-margin 1.0 # Multiplier on track-via clearance (1.0 = min DRC, default) --hole-to-hole-clearance 0.2 # Minimum drill hole edge-to-edge clearance (mm) --board-edge-clearance 0.0 # Clearance from board edge (0 = use track clearance) # Strategy --ordering mps # mps | inside_out | original --layers F.Cu B.Cu # Routing layers (default: 2-layer) --layer-costs 1.0 3.0 # Per-layer cost multipliers (1.0-1000) # Default: 4+ layers = all 1.0; 2 layers = F.Cu=1.0, B.Cu=3.0 # Order matches --layers. Use to prefer certain layers (e.g., keep signals on F.Cu) --no-bga-zones # Allow routing through all BGA areas --no-bga-zones U1 U3 # Allow routing through specific BGAs only (or all if none given) # Proximity penalties --stub-proximity-radius 2.0 # Radius around stubs to penalize (mm) --stub-proximity-cost 0.2 # Cost penalty near stubs (mm equivalent) --bga-proximity-radius 7.0 # Radius around BGA edges to penalize (mm) --bga-proximity-cost 0.2 # Cost penalty near BGA edges (mm equivalent) --track-proximity-distance 2.0 # Radius around routed tracks (mm, same layer) --track-proximity-cost 0.0 # Cost penalty near tracks (0 = disabled) --vertical-attraction-radius 1.0 # Radius for cross-layer track attraction (mm) --vertical-attraction-cost 0.0 # Cost bonus for cross-layer alignment (0 = disabled) --ripped-route-avoidance-radius 1.0 # Radius around ripped route corridors (mm) --ripped-route-avoidance-cost 0.1 # Cost penalty for routing through ripped corridors (0 = disabled) # Bus routing (parallel groups of nets) # Detects groups of nets with clustered endpoints and routes them together. # Routes middle net first (guide track), then alternates outward with attraction # to keep traces parallel. Use --verbose to see routing order and attraction relationships. --bus # Enable bus detection and parallel routing --bus-detection-radius 5.0 # Max endpoint distance to form bus group (mm) --bus-attraction-radius 5.0 # Attraction radius from neighbor track (mm) --bus-attraction-bonus 5000 # Cost bonus for staying parallel to neighbor --bus-min-nets 2 # Minimum nets to form a bus group # Guide corridor: route selected nets to follow a polyline drawn on a User layer (issue #7) --guide-corridor # Steer routed nets along the drawn guide polyline --guide-corridor-layer User.1 # User layer the guide polyline is drawn on --guide-corridor-spacing 0.0 # Max mm between waypoints (0 = drawn vertices only; >0 subdivides) # Keepout zones: keep routed tracks out of polygons drawn on a User layer (issue #27) --keepout # Keep routed tracks out of the drawn keepout polygons --keepout-layer User.2 # User layer the keepout polygons are drawn on # Layer optimization --no-stub-layer-swap # Disable stub layer switching # Target swap optimization --swappable-nets "*rx*" # Glob patterns for nets that can have targets swapped --schematic-dir /path/to/kicad # Optional: sync pad swaps to .kicad_sch files (disabled by default) # Updates lib_symbols in ALL files containing the symbol --crossing-penalty 1000 # Penalty for crossing assignments (default: 1000) --no-crossing-layer-check # Count crossings regardless of layer (default: same-layer only) --mps-reverse-rounds # Route most-conflicting MPS groups first (instead of least) --mps-layer-swap # Try layer swaps to resolve MPS crossing conflicts --mps-segment-intersection # Force segment intersection method for MPS (auto when no BGAs) # Length matching (for DDR4 DQ/DQS signals) --length-match-group auto # Auto-group DDR4 nets by byte lane (DQ0-7+DQS0, DQ8-15+DQS1, etc) --length-match-group "pattern1" "pattern2" # Manual grouping by net patterns --length-match-tolerance 0.1 # Acceptable length variance within group (mm) --meander-amplitude 1.0 # Height of meanders perpendicular to trace (mm) # Time matching (alternative to length matching) --time-matching # Match propagation time instead of length (accounts for layer dielectric) --time-match-tolerance 1.0 # Acceptable time variance within group (ps) # Debug --verbose # Print detailed diagnostic output --debug-lines # Output debug geometry on User layers --skip-routing # Skip routing, only do swaps and write debug info --debug-memory # Print memory usage statistics during routing --add-teardrops # Add teardrop settings to all pads in output file --stats # Print A* search statistics (cells expanded, heuristic efficiency, etc.)

python route_planes.py kicad_files/input.kicad_pcb [output.kicad_pcb] --nets GND --plane-layers B.Cu [OPTIONS] # Output options (default: input_routed.kicad_pcb) --overwrite, -O # Overwrite input file instead of creating _routed copy # Required (can specify multiple nets/plane layers) --nets, -n GND VCC # Net name(s) for planes (e.g., GND VCC +3.3V) # Use | to share a layer: "VA19|VA11" creates Voronoi-partitioned zones --plane-layers, -p In1.Cu In2.Cu # Plane layer(s), one per net (or one per net group) # Via/trace geometry --via-size 0.5 # Via outer diameter (mm) --via-drill 0.3 # Via drill size (mm) --track-width 0.3 # Track width for via-to-pad connections (mm) --clearance 0.25 # Clearance (mm) # Zone options --zone-clearance 0.2 # Zone clearance from other copper (mm) --min-thickness 0.1 # Minimum zone copper thickness (mm) # Algorithm --grid-step 0.1 # Grid resolution (mm) --max-search-radius 10.0 # Max radius to search for valid via position (mm) --max-via-reuse-radius 1.0 # Max radius to prefer reusing existing via (mm) --close-via-radius 0.5 # Radius to check for nearby vias before placing new one (default: 2.5 * via-size) --hole-to-hole-clearance 0.2 # Minimum drill hole clearance (mm) --layers, -l F.Cu In1.Cu In2.Cu B.Cu # All copper layers for routing and via span --layer-costs 1.0 1.0 1.0 1.0 # Per-layer cost multipliers (1.0-1000) # Default: 4+ layers = all 1.0; 2 layers = F.Cu=1.0, B.Cu=3.0 --board-edge-clearance 0.5 # Zone clearance from board edge (mm) # Multi-net plane layers (Voronoi partitioning) --plane-proximity-radius 2.0 # Proximity radius for routing around other nets' vias (mm) --plane-proximity-cost 5.0 # Proximity cost for routing around other nets' vias --plane-track-via-clearance 0.8 # Clearance from MST track center to other nets' via centers (mm) --voronoi-seed-interval 2.0 # Sample interval for seed points along connection routes (mm) --plane-max-iterations 200000 # Max A* iterations for plane connection routing # Blocker rip-up --rip-blocker-nets # Rip up nets blocking via placement --max-rip-nets 3 # Max blocker nets to rip up per pad (default: 3) --reroute-ripped-nets # Automatically re-route ripped nets after via placement --power-nets "*GND*" "*VCC*" # Glob patterns for power nets (wider tracks when rerouting) --power-nets-widths 0.4 0.5 # Track widths for each power-net pattern # Debug --dry-run # Analyze without writing output --verbose, -v # Print detailed debug messages --debug-lines # Draw MST routes on User.1, User.2, etc. per net --add-teardrops # Add teardrop settings to all pads in output file # GND return via placement (for signal integrity) --add-gnd-vias # Add GND vias near signal vias for return current paths --gnd-via-net GND # Net name for GND vias (default: GND) --gnd-via-distance 2.0 # Max distance from signal via to place GND via (mm, default: 2.0)

KiCadRoutingToolsFork

KiCad Routing Tools

Features

KiCad Routing Tools

Features

Quick Start

1. Get the Code

2. Install the Rust Router

Building from source (optional)

3. Choose Your Interface

KiCad Plugin

AI assistance (Claude tab)

Installation

Releasing a new version (maintainers)

Usage

Plugin Tabs

Command-Line Interface

Net Pattern Syntax

Route Nets

3. Create Power/Ground Planes

3b. Repair Disconnected Plane Regions

4. Verify Results

5. Power Net Analysis

6. High-Speed Net Analysis

7. Integration Tests

Documentation

Project Structure

Module Overview

Core Routing

Routing Loops

Net Analysis

Optimization

I/O and Utilities

Performance

Common Options

Single-Ended Routing (route.py)

Differential Pair Routing (route_diff.py)

Power/Ground Plane Via Connections (route_planes.py)

Disconnected Plane Region Repair (route_disconnected_planes.py)

Requirements

Limitations

License