# Documents

Diagrams, the BOM, and the datasheets for parts this design actually depends on.

## Diagrams

| File | Shows |
|---|---|
| `three-board-overview.svg` | All three boards at the same key spacing |
| `half-left-staggered.svg` | Left half — 34 keys, six clean columns |
| `half-right-staggered.svg` | Right half — 41 keys |
| `numpad-layout.svg` | Numpad — 25 keys plus the volume encoder |
| `104-key-split.svg` | How a full 104 maps across the three boards |
| `half-left.svg`, `half-right.svg` | The earlier row-staggered split, kept for reference |

`bom.csv` carries LCSC part numbers, JLC basic/extended status and the
swap-dependent parts.

## Datasheets

Only the parts this design depends on. The wider WCH collection — including the
CH32X035 and CH32V203 docs used to rule out crystal-less USB — lives in
`~/Documents/Projects/WCH CH ICs/`.

| File | Part | Why it's here |
|---|---|---|
| `CH32L103DS0.PDF` | CH32L103C8T6 | The MCU. Pinout, 64 K flash / 20 K SRAM, HSI accuracy table (§3.3.6), USBFS with 8 device endpoints (§1.4.20). |
| `CH32L103RM.PDF` | CH32L103C8T6 | Reference manual. USB clock path (§3.3.5.6), `RB_UC_DEV_PU_EN` internal 1.5 kΩ D+ pull-up, HSICAL/HSITRIM. |
| `CH334DS1.PDF` | CH334R | The hub. Variant feature table (which packages expose `PSELF` and port power switching), crystal-free caveats (§6.2), and the CH213 reference design for VBUS protection. |
| `STM32F103x8xB_datasheet_rev1.PDF` | STM32F103C8T6 | The pin-compatible escape-hatch MCU. Needed for the LQFP48 pin-number overlay against the CH32L103. |

## ⚠️ The STM32F103 copy is Rev 1 (preliminary)

st.com refuses scripted download (HTTP/2 reset on curl; its CSP also blocks
exfiltrating a browser-side fetch). This copy came from a third-party mirror and
is the **early preliminary revision, 65 pages** — the current one is Rev 20 at
~117 pages.

For the LQFP48 pin numbering it is fine: that table has not changed since 2007,
and PC13/PC14/PC15, OSC_IN/OSC_OUT, NRST, PA11/PA12, PA13/PA14 and BOOT0 are all
present and verified in this copy.

**Do not trust it for anything electrical** — absolute maximums, timings, current
consumption and errata have all moved since Rev 1. For those, pull the current
datasheet by hand from
<https://www.st.com/resource/en/datasheet/stm32f103c8.pdf> in a browser and
replace this file.