JLCPCB / LCSC Parts Check

How to verify that LCSC part numbers in the schematic match the intended components.

1. Extract All LCSC Numbers from the Schematic

Use the following Python snippet to parse cm4-nrf54.kicad_sch and dump all component references with their value and LCSC field:

import re

with open('cm4-nrf54.kicad_sch', 'r') as f:
    content = f.read()

lcsc_pattern = re.compile(r'\(property\s*"(?:LCSC|lcsc|LCSC Part)"\s*"([^"]+)"')
field_pattern = re.compile(r'\(property\s*"(LCSC|lcsc|LCSC Part)"\s*"([^"]+)"')

blocks = re.split(r'\n\s*\(symbol\s+\(lib_id', content)

results = []
for block in blocks[1:]:
    ref_m  = re.search(r'\(property\s*"Reference"\s*"([^"]+)"', block)
    val_m  = re.search(r'\(property\s*"Value"\s*"([^"]+)"', block)
    lcsc_m = lcsc_pattern.search(block)
    field_m = field_pattern.search(block)

    ref   = ref_m.group(1)  if ref_m  else '?'
    val   = val_m.group(1)  if val_m  else '?'
    lcsc  = lcsc_m.group(1) if lcsc_m else ''
    field = field_m.group(1) if field_m else ''

    if ref.startswith('#') or ref == '?':
        continue
    results.append((ref, val, lcsc, field))

results.sort(key=lambda x: (
    ''.join(filter(str.isalpha, x[0])),
    int(''.join(filter(str.isdigit, x[0])) or '0')
))

for ref, val, lcsc, field in results:
    print(f'{ref:12} {val:42} {lcsc:15} {field}')

Note: KiCad schematics use three different field names for the LCSC number: LCSC, lcsc, and LCSC Part — the script above catches all three.

2. Verify Each LCSC Number

For each non-trivial component, open the LCSC product page directly:

https://www.lcsc.com/product-detail/C<NUMBER>.html

The page title shows the actual manufacturer part number. Cross-check against the schematic Value field.

What to look for

Wrong part — the LCSC number resolves to a completely different component (e.g. a 22Ω resistor assigned to a 220R position, or an ADC with the wrong channel count).
Package mismatch — the part is the right IC but in a different package than the KiCad footprint (e.g. SOT-363 assigned to a SOT-23-5 footprint).
Wrong variant — same family but different spec (e.g. PCM1862 vs PCM1863, which differ in channel count).
Part not found — the LCSC number returns a 404 / "Page Not Found". The part may be new, discontinued, or the number is a typo.
Missing LCSC — component has no LCSC field at all. If it is a real assembly part (not a mechanical hole, test point, or solder jumper), it needs one.

3. Check JLCPCB Assembly Availability

Not all LCSC parts can be assembled by JLCPCB. To check:

https://jlcpcb.com/partdetail/<MANUFACTURER>-<PART>/C<NUMBER>

Or search directly at https://jlcpcb.com/parts.

Stock status meanings

Status	Meaning
In-stock, qty shown	Orderable, JLCPCB can assemble
C9900xxxxxx number	Consigned part — you must supply the component
"unavailable for purchase but can still be used in assembly"	Must be consigned; cannot be bought through JLCPCB

4. Finding Alternatives

When a part is not available on LCSC/JLCPCB, search for drop-in alternatives:

Search site:lcsc.com <part number> or site:jlcpcb.com <part number>
Check the Raspberry Pi / EasyEDA forums for CM4-specific parts (e.g. RJ45 MagJack alternatives)
Common compatible replacements for this project:

Original	Alternative	LCSC	Notes
Bel Fuse A70-112-331N126 (MagJack)	LINK-PP LPJG0926HENL	C22457393	Pin-compatible, 387 pcs in stock at JLCPCB

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