imrishabh18/pedometer

docs/model-alignment.md

> Historical module-revision record. Rev B uses a bare U1 and separate ANT1; these M1 images and dimensions do not describe the active board.

# M1 placement and model alignment

M1 is the RF-star RF-BM-2340C2 containing the CC2340R5. Its body center is now **(−10, 7.5) mm**, placing its 8 mm body 1 mm from the left board edge. Its crystal and local capacitors move 3 mm left with it. The PCB remains 30 × 28 mm.

The imported supplier 3D asset depicted a shielded module with a different contact arrangement. It has been replaced by a local procedural assembly model, based on the RF-star drawing. Its **8 × 8 × 1.7 mm envelope**, 1 mm contact pitch and asymmetric contact rows follow pages 8 and 15 of the [RF-star hardware datasheet V1.0](https://www.rfstariot.com/uploadfile/downloads/RF-BM-2340C2%20Hardware%20Datasheet%20V1.0%2020240521.pdf). The exposed MCU, crystal, antenna and small component envelopes are illustrative, based on the module photograph; they are not production mechanical CAD.

The footprint and model share one contact coordinate table and an origin at the module body center. At zero PCB rotation:

| Contacts | PCB pad centers, mm | Module edge, mm |
|---|---|---|
| 1–7, left side | x = −13.837432; y = 10, 9, 8, 7, 6, 5, 4 | x = −14 |
| 8–15, right side | x = −6.162568; y = 4, 5, 6, 7, 8, 9, 10, 11 | x = −6 |

The wider host lands intentionally extend beyond the module edge for solder fillets. Every side castellation is centered on its corresponding pad's y coordinate. Pin 16 is the unused external RF contact at the top of the module; it intentionally has no host copper landing. This revision uses the onboard chip antenna.

The all-layer antenna keepout is x = −14.5…−7.2 mm, y = 10.4…13.5 mm. It covers the antenna end of M1 and the free board area toward the corner, while avoiding pin 15's ground landing. Its outer extension is clipped at the board margin after moving M1 left. The rectangle is a design reserve guided by the datasheet's edge-placement guidance, not a quoted manufacturer clearance dimension.

The close-up renders below use the rebuilt, routed Circuit JSON. Other component bodies are omitted to expose the surrounding host copper and lands; M1's body and contacts are rendered at their actual coordinates. The static exporter displays the procedural model in neutral gray.

- [Top view](../review/m1-top.png)
- [Oblique view](../review/m1-oblique.png)
- [Native checks](../review/checks.txt)

RF performance and enclosure effects still need prototype measurement.