# JLCPCB / LCSC Parts Check

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

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## 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:

```python
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.

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## 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.

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## 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 |

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## 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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