104 lines
3.6 KiB
Markdown
104 lines
3.6 KiB
Markdown
# JLCPCB / LCSC Parts Check
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How to verify that LCSC part numbers in the schematic match the intended components.
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---
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## 1. Extract All LCSC Numbers from the Schematic
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Use the following Python snippet to parse `cm4-nrf54.kicad_sch` and dump all component references with their value and LCSC field:
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```python
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import re
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with open('cm4-nrf54.kicad_sch', 'r') as f:
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content = f.read()
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lcsc_pattern = re.compile(r'\(property\s*"(?:LCSC|lcsc|LCSC Part)"\s*"([^"]+)"')
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field_pattern = re.compile(r'\(property\s*"(LCSC|lcsc|LCSC Part)"\s*"([^"]+)"')
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blocks = re.split(r'\n\s*\(symbol\s+\(lib_id', content)
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results = []
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for block in blocks[1:]:
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ref_m = re.search(r'\(property\s*"Reference"\s*"([^"]+)"', block)
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val_m = re.search(r'\(property\s*"Value"\s*"([^"]+)"', block)
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lcsc_m = lcsc_pattern.search(block)
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field_m = field_pattern.search(block)
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ref = ref_m.group(1) if ref_m else '?'
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val = val_m.group(1) if val_m else '?'
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lcsc = lcsc_m.group(1) if lcsc_m else ''
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field = field_m.group(1) if field_m else ''
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if ref.startswith('#') or ref == '?':
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continue
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results.append((ref, val, lcsc, field))
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results.sort(key=lambda x: (
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''.join(filter(str.isalpha, x[0])),
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int(''.join(filter(str.isdigit, x[0])) or '0')
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))
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for ref, val, lcsc, field in results:
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print(f'{ref:12} {val:42} {lcsc:15} {field}')
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```
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> **Note:** KiCad schematics use three different field names for the LCSC number:
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> `LCSC`, `lcsc`, and `LCSC Part` — the script above catches all three.
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---
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## 2. Verify Each LCSC Number
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For each non-trivial component, open the LCSC product page directly:
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```
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https://www.lcsc.com/product-detail/C<NUMBER>.html
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```
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The page title shows the actual manufacturer part number. Cross-check against the schematic `Value` field.
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### What to look for
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- **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).
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- **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).
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- **Wrong variant** — same family but different spec (e.g. PCM1862 vs PCM1863, which differ in channel count).
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- **Part not found** — the LCSC number returns a 404 / "Page Not Found". The part may be new, discontinued, or the number is a typo.
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- **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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---
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## 3. Check JLCPCB Assembly Availability
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Not all LCSC parts can be assembled by JLCPCB. To check:
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```
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https://jlcpcb.com/partdetail/<MANUFACTURER>-<PART>/C<NUMBER>
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```
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Or search directly at `https://jlcpcb.com/parts`.
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### Stock status meanings
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| Status | Meaning |
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|--------|---------|
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| **In-stock, qty shown** | Orderable, JLCPCB can assemble |
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| **C9900xxxxxx** number | Consigned part — you must supply the component |
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| *"unavailable for purchase but can still be used in assembly"* | Must be consigned; cannot be bought through JLCPCB |
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---
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## 4. Finding Alternatives
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When a part is not available on LCSC/JLCPCB, search for drop-in alternatives:
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- Search `site:lcsc.com <part number>` or `site:jlcpcb.com <part number>`
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- Check the Raspberry Pi / EasyEDA forums for CM4-specific parts (e.g. RJ45 MagJack alternatives)
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- Common compatible replacements for this project:
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| Original | Alternative | LCSC | Notes |
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|----------|-------------|------|-------|
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| Bel Fuse A70-112-331N126 (MagJack) | LINK-PP LPJG0926HENL | **C22457393** | Pin-compatible, 387 pcs in stock at JLCPCB |
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--- |