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periscope/backend/services/passive_from_value.py
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micheleandCursor edbb47a08b Resolve passives from catalog, BOM value, and Murata LQW18AN without an LLM.
Skip the model (and the credit gate) when LCSC/DigiKey already list C/V/Z, when the BOM value is a single R/C/L/FB token, or when the MPN is an LQW18AN inductor. Ferrite beads keep impedance, not invented henries; value-only specs stay out of the shared library.

Co-authored-by: Cursor <cursoragent@cursor.com>
2026-08-28 20:25:34 +02:00

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"""Parse a BOM Value string into typed passive specs without an LLM."""
from __future__ import annotations
import re
from backend.pinscopex.models import ComponentModel, SimpleComponentSpecs
from backend.pinscopex.resolve_passives import simple_to_typed_passive_specs
from backend.services.passive_from_distributor import _spice
_PLACEHOLDER = re.compile(
r"^(?:dnp|dni|dns|nc|n/?c|n/?a|np|nfs|tbd|todo|jumper|jmp|short|open|-|—|)$",
re.I,
)
_CAP = re.compile(
r"^(?P<num>\d+(?:\.\d+)?)\s*(?P<mul>[pnuμµmk])?\s*[fF]$",
)
_IND = re.compile(
r"^(?P<num>\d+(?:\.\d+)?)\s*(?P<mul>[pnuμµmk])?\s*H$",
re.I,
)
_RES_UNIT = re.compile(
r"^(?P<num>\d+(?:\.\d+)?)\s*(?P<mul>[pnuμµmkM])?\s*(?:ohms?|Ω|R)$",
re.I,
)
_RES_BARE_MUL = re.compile(
r"^(?P<num>\d+(?:\.\d+)?)(?P<mul>[kKmM])$",
)
_EURO_R = re.compile(
r"^(?P<a>\d+)[kK](?P<b>\d+)$",
)
_FB = re.compile(
r"^(?P<num>\d+(?:\.\d+)?)\s*(?P<mul>[kKmM])?\s*(?:ohms?|Ω|R)"
r"(?:@\s*(?P<freq>\d+(?:\.\d+)?\s*(?:kHz|MHz|GHz|Hz)))?$",
re.I,
)
def is_placeholder_value(value: str) -> bool:
return bool(_PLACEHOLDER.match((value or "").strip()))
def _model(mpn: str, subtype: str, values: dict[str, str]) -> ComponentModel | None:
specs = SimpleComponentSpecs(
specs_type="passive",
component_subtype=subtype,
values=values,
)
try:
typed = simple_to_typed_passive_specs(specs)
except (ValueError, TypeError):
return None
return ComponentModel(mpn=mpn, specs=typed)
def specs_from_bom_value(
mpn: str, value: str, ref_prefix: str,
) -> ComponentModel | None:
"""Map ``18pF`` / ``4.7k`` / ``10uH`` / ``600R@100MHz`` to typed specs.
Returns None for placeholders (DNP, NC, JUMPER) and for strings that
are not a single passive value. Callers must not save the result to the
shared library.
"""
raw = (value or "").strip()
prefix = (ref_prefix or "").upper()
if not raw or is_placeholder_value(raw):
return None
compact = re.sub(r"\s+", "", raw)
if prefix == "FB" or "@" in compact:
m = _FB.match(compact) or _FB.match(raw)
if m:
z = _spice(m.group("num"), m.group("mul"), "ohm")
freq = re.sub(r"\s+", "", m.group("freq") or "")
values = {
"impedance_ohm": z,
"value_formatted": f"{z}@{freq}" if freq else z,
}
return _model(mpn, "passive.ferrite_bead", values)
if prefix in {"C", ""}:
m = _CAP.match(compact) or _CAP.match(raw)
if m:
farads = _spice(m.group("num"), m.group("mul"), "F")
return _model(mpn, "passive.capacitor", {
"value_farads": farads,
"value_formatted": farads,
})
if prefix in {"L", ""}:
m = _IND.match(compact) or _IND.match(raw)
if m:
henries = _spice(m.group("num"), m.group("mul"), "H")
return _model(mpn, "passive.inductor", {
"value_henries": henries,
"value_formatted": henries,
})
if prefix in {"R", ""}:
m = _EURO_R.match(compact)
if m:
ohms = float(f"{m.group('a')}.{m.group('b')}") * 1e3
formatted = _spice(str(ohms), None, "ohm")
return _model(mpn, "passive.resistor", {
"value_ohms": formatted,
"value_formatted": formatted,
})
m = _RES_UNIT.match(compact) or _RES_BARE_MUL.match(compact)
if m:
formatted = _spice(m.group("num"), m.group("mul"), "ohm")
return _model(mpn, "passive.resistor", {
"value_ohms": formatted,
"value_formatted": formatted,
})
return None