Reviewed the CH9102X part data and cross-checked it against the WCH CH9102 datasheet.
What I found
- MPN: CH9102X — matches project metadata.
- Manufacturer: WCH — matches.
- Package: QFN28X5, 5 × 5 mm, 0.5 mm pitch, exposed GND pad — project only says QFN, so it should be made more specific.
- Datasheet: Already set, so I did not overwrite it.
- Symbol pin mapping: Pins 1–28 match the datasheet pin names and order.
- Footprint: 28 perimeter pads plus an exposed GND pad are present, matching the QFN28 + EP requirement at a high level.
Key specs
- USB 2.0 Full-Speed, 12 Mbps
- UART baud rate: 50 bps to 4 Mbps
- CH9102X UART I/O: 3.3 V logic
- Supply: 5 V via VDD5 with internal 3.3 V regulator, or 3.3 V with VDD5 tied to V3
- Operating temperature: −40 °C to +85 °C
- No external crystal required
Mismatches / issues flagged
- The exposed pad is represented as GND pin 29, but the datasheet defines it as pin 0 / exposed GND pad. Electrically OK, but the pin number should ideally be corrected.
- All symbol terminals are currently marked Bi-Directional; datasheet-specific types should be applied instead: power, input, output, USB, I/O, NC.
- Package metadata should be updated from generic QFN to QFN28X5 / 5×5 mm / 0.5 mm pitch / exposed pad.
- NC pins 13–15 should be clearly marked NC and left floating.