micheleandCursor
6fc2ac583d
Use the vendored Hammerstad-Jensen/Cohn engine for microstrip, stripline, and coupled-diff advice. Skip OpenEMS/pcbnew and refuse CPWG rather than inventing a number. Co-authored-by: Cursor <cursoragent@cursor.com>
76 lines
2.2 KiB
Python
76 lines
2.2 KiB
Python
"""Standalone impedance calculator (no PCB, no findings)."""
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from __future__ import annotations
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from dataclasses import asdict
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from typing import Literal
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from fastapi import APIRouter, HTTPException
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from pydantic import BaseModel
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from backend.pinscopex.impedance import (
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GeometryError,
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TraceGeometry,
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coupled_diff_z,
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cpw_z0,
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export_kicad_dru,
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microstrip_z0,
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solve_width,
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stackup_targets,
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stripline_z0,
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)
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router = APIRouter(tags=["impedance"])
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class ImpedanceRequest(BaseModel):
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mode: Literal["trace", "stackup"] = "trace"
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kind: Literal["microstrip", "stripline", "cpw", "diff"] | None = None
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h: float
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er: float
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t: float = 0.035
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w: float | None = None
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s: float | None = None
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target_z: float | None = None
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def _z_for_kind(kind: str, geo: TraceGeometry) -> dict:
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if kind == "microstrip":
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return {"z0": microstrip_z0(geo), "w_mm": geo.w, "s_mm": geo.s, "kind": kind}
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if kind == "stripline":
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return {"z0": stripline_z0(geo), "w_mm": geo.w, "s_mm": geo.s, "kind": kind}
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if kind == "cpw":
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return {"z0": cpw_z0(geo), "w_mm": geo.w, "s_mm": geo.s, "kind": kind}
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if kind == "diff":
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zodd, zeven, zdiff = coupled_diff_z(geo)
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return {
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"z0": None,
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"zodd": zodd,
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"zeven": zeven,
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"zdiff": zdiff,
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"w_mm": geo.w,
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"s_mm": geo.s,
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"kind": kind,
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}
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raise GeometryError(f"unknown kind {kind}")
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@router.post("/impedance")
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def compute_impedance(body: ImpedanceRequest):
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try:
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if body.mode == "stackup":
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s = body.s if body.s is not None else 0.2
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targets = stackup_targets(h=body.h, er=body.er, t=body.t, s=s)
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return {
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"targets": {k: asdict(v) for k, v in targets.items()},
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"kicad_dru": export_kicad_dru(targets),
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}
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kind = body.kind or "microstrip"
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w = body.w
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if body.target_z is not None:
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w = solve_width(kind, body.target_z, body.h, body.er, body.t, s=body.s)
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geo = TraceGeometry(h=body.h, er=body.er, t=body.t, w=w, s=body.s)
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return _z_for_kind(kind, geo)
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except GeometryError as exc:
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raise HTTPException(400, str(exc)) from exc
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