imrishabh18/pedometer

This code defines and assembles a simple radio receiver hardware circuit using specific imported capacitors, inductors, RF connectors, and oscillator components with precise footprints and schematic attributes.

Version
1.1.3
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docs/usb-c.md

# USB-C charging revision

J2 is now a SHOU HAN TYPE-C 6P receptacle (C456012). It replaces the two-pin JST charging input. The bare-chip revision is 40 × 38 × 1 mm, with four copper layers. The port opens at the top edge, clear of the ANT1 antenna region. J1 battery/NTC, J3 OLED and J4 SWD remain JST-SH.

## Electrical changes

- Both VBUS contacts feed VIN5, C3 and the BQ25150 IN ball.
- CC1 and CC2 each have their own 5.1 kΩ, 1% resistor: R12/R13, 0402WGF5101TCE, C25905. They are separate nets and support either plug orientation.
- D1 is an ESD5Z5.0T1G transient clamp (C82044), cathode to VBUS and anode to GND.
- The two ground contacts and four mounting tabs connect to GND. Each tab has a separate logical pin so all four physical slots receive routes.
- This is a 5 V charging-only sink. USB data, USB PD and USB programming are not implemented. The charger retains its default 100 mA input limit and the existing firmware's nominal 20 mA charge setting.

The new components have positive JLCSearch stock records in [stock-check](stock-check.md). The assembly process requirements in fabrication-review.md remain applicable; all PCB passives now have exact MPNs.

## Layout and assembly

C2, R7 and SW1 were moved to accommodate the port; the original BGA and crystal placements are retained. All traces and vias are generated by the routing pipeline. No manual `<via />` components are used.

The four shell slots are nominal 0.60 × 1.40 mm, with plated walls. The manufacturing drill export must contain four G85 slots, alongside the through-vias and the two non-plated mounting holes. Reserve space beyond the PCB edge for the USB shell, mating cable and enclosure opening.

The imported TVS pad polygons were represented as equivalent rectangles, preserving their vertices' bounds. This gives the renderer and geometry audit explicit pad centers and sizes. The USB connector retains its supplier footprint and model; mounting contacts were individually named and decorative under-body legend removed.

USB-C input and protection have their own fourth A4 schematic sheet. [Pin cross-reference](interfaces.md), [USB-C schematic](../review/schematic-4-usb.png).

## Verification

Current routing, drill counts and fabrication status are recorded in [fabrication review](fabrication-review.md). Earlier USB-C revision measurements are historical.