diff --git a/Documents/README.md b/Documents/README.md
index 8cc4b56..ff5f0fa 100644
--- a/Documents/README.md
+++ b/Documents/README.md
@@ -9,9 +9,21 @@ lives in `~/Documents/Projects/WCH CH ICs/`.
 | `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. |
 
-## Missing
+## ⚠️ The STM32F103 copy is Rev 1 (preliminary)
 
-- **STM32F103C8T6 datasheet** — the pin-compatible escape-hatch MCU. ST's site
-  refused automated download; grab it from st.com or the LCSC CDN and drop it
-  here. Needed to do the pin-number overlay flagged in the top-level README.
+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.
diff --git a/Documents/STM32F103x8xB_datasheet_rev1.PDF b/Documents/STM32F103x8xB_datasheet_rev1.PDF
new file mode 100644
index 0000000..2ecce65
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