NEXTPNR-ECP5(1)

📦
version 0.10 · 7 versions
, in ubuntu stonking

✨ NEXTPNR-ECP5 ✨

okay bestie come CLOSE because this is the manual page for nextpnr-ecp5, and honestly it's giving "the whole pipeline in one binary" 💅 we're talking Next Generation Place and Route, version 0.10-5, and it lives under the manual section 1 for General Commands. yes it's a lot of flags. no you don't have to memorise them all. let's get into it 🫶

🌸 NAME 🌸

nextpnr-ecp5 — Next Generation Place and Route 💖

🦋 DESCRIPTION 🦋

nextpnr-ecp5 is Next Generation Place and Route, and this particular one is Version 0.10-5 ⭐ it takes your design from "a pile of logic" to "actually placed and routed", and it gives you approximately one million knobs to turn while it does it. no cap.

🧁 General options

the everyday stuff, the buttons you'll actually be mashing:

  • -h, --help — show help 🙋‍♀️
  • -v, --verbose — verbose output, aka it tells you everything
  • -q, --quiet — quiet mode, only errors and warnings get shown 🤫
  • --Werror — turn warnings into errors. dramatic but valid 💀
  • -l, --log arg — log file; all log messages are written to this file regardless of -q 📝
  • --debug — debug output
  • --debug-placer — debug output from the placer only
  • --debug-router — debug output from the router only
  • --threads arg — number of threads for passes where this is configurable 🧵
  • -f, --force — keep running after errors. chaotic. iconic.
  • --run arg — python file to execute instead of default flow 🐍
  • --pre-pack arg — python file to run before packing
  • --pre-place arg — python file to run before placement
  • --pre-route arg — python file to run before routing
  • --post-route arg — python file to run after routing
  • --on-failure arg — python file to run in event of crash for design introspection 😭 (when it all goes wrong, this is your little forensic buddy)
  • --json arg — JSON design file to ingest
  • --write arg — JSON design file to write
  • --top arg — name of top module 👑
  • --seed arg — seed value for random number generator 🎲
  • -r, --randomize-seed — randomize seed value for random number generator
  • --placer arg — placer algorithm to use; available: sa, heap, static; default: heap
  • --router arg — router algorithm to use; available: router1, router2; default: router1
  • --slack_redist_iter arg — number of iterations between slack redistribution
  • --cstrweight arg — placer weighting for relative constraint satisfaction
  • --starttemp arg — placer SA start temperature 🌡️
  • --pack-only — pack design only without placement or routing
  • --no-route — process design without routing
  • --no-place — process design without placement
  • --no-pack — process design without packing
  • --ignore-loops — ignore combinational loops in timing analysis
  • --ignore-rel-clk — ignore clock-to-clock relations in timing checks
  • -V, --version — show version
  • --test — check architecture database integrity ✅
  • --freq arg — set target frequency for design in MHz
  • --timing-allow-fail — allow timing to fail in design (it's fine, it's fine, everything's fine 🙈)
  • --no-tmdriv — disable timing-driven placement
  • --sdc arg — Generic timing constraints SDC file to load
  • --sdf arg — SDF delay back-annotation file to write
  • --sdf-cvc — enable tweaks for SDF file compatibility with the CVC simulator
  • --no-print-critical-path-source — disable printing of the line numbers associated with each net in the critical path
  • --placer-heap-alpha arg — placer heap alpha value (float, default: 0.1)
  • --placer-heap-beta arg — placer heap maximum placement density (float, default: 0.9)
  • --placer-heap-critexp arg — placer heap criticality exponent (int, default: 2)
  • --placer-heap-timingweight arg — placer heap timing weight (int, default: 10)
  • --placer-heap-cell-placement-timeout arg — allow placer to attempt up to max(10000, total cells^2 / N) iterations to place a cell (int N, default: 8, 0 for no timeout)
  • --static-dump-density — write density csv files during placer-static flow
  • --parallel-refine — use new experimental parallelised engine for placement refinement ⚡
  • --router2-heatmap arg — prefix for router2 resource congestion heatmaps 🔥
  • --tmg-ripup — enable experimental timing-driven ripup in router
  • --router2-tmg-ripup — enable experimental timing-driven ripup in router (deprecated; use --tmg-ripup instead) 💀
  • --router2-alt-weights — use alternate router2 weights
  • --report arg — write timing and utilization report in JSON format to file
  • --detailed-timing-report — Append detailed net timing data to the JSON report
  • --placed-svg arg — write render of placement to SVG file 🎨
  • --routed-svg arg — write render of routing to SVG file

🧚 Architecture specific options

this is the ECP5 part, the part that actually knows what chip you're talking to:

  • --package arg — select device package (defaults to CABGA381)
  • --speed arg — select device speedgrade (6, 7 or 8)
  • --basecfg arg — base chip configuration in Trellis text format (deprecated)
  • --override-basecfg arg — base chip configuration in Trellis text format
  • --textcfg arg — textual configuration in Trellis format to write
  • --lpf arg — LPF pin constraint file(s) 📌
  • --lpf-allow-unconstrained — don't require LPF file(s) to constrain all IO
  • --no-promote-globals — disable all global promotion
  • --out-of-context — disable IO buffer insertion and global promotion/routing, for building pre-routed blocks (experimental)
  • --disable-router-lutperm — don't allow the router to permute LUT inputs
🎀 heads up bestie: --basecfg is deprecated, and --router2-tmg-ripup is deprecated too (use --tmg-ripup instead). also --out-of-context and --parallel-refine are on their experimental arc — slay responsibly 💅

and that's the whole thing, you made it to the end ily 🥹 this was nextpnr-ecp5 version 0.10-5, from March 2026 — go place and route something gorgeous, you've got this 💖✨🦋

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