Here’s how you can identify a fake [STM32F103C8T6](https://www.ampheo.com/product/stm32f103c8t6-131876) — a very common target for counterfeiting, especially in blue pill boards:

**1. Visual Inspection (STM32F103C8T6)**
**Markings & Text:**

Genuine ST chips have sharp, laser-etched markings with consistent fonts.

Fake chips may have:

* Misaligned or blurry text.
* Wrong font or incorrect spacing.
* Non-standard logos (ST or ARM).
* Suspicious or inconsistent date codes (e.g. too recent or very old).

**Surface Finish:**

* Fake chips may be sanded/resurfaced and re-printed.
* Look for signs of abrasion or coating inconsistency.

**Pin 1 Marking:**

* Authentic chips usually have a small dot or indentation at pin 1.
* Fakes may have missing or crude markings.

**2. Functional Behavior**
**Flash Size Check:**

* [STM32F103C8T6](https://www.onzuu.com/product/stmicroelectronics-stm32f103c8t6-3232092) officially has 64 KB of flash, but many fakes report 128 KB (copied from STM32F103CBT6).
* Run STM32CubeProgrammer, ST-Link Utility, or a test firmware to verify flash size and behavior.

**Weird Peripherals:**

* Some fakes are based on CS32F103, GD32F103, or even non-ARM chips.
* Features like USB, CAN, or DMA might behave differently or not work at all.

**Signature or ID Check:**

Use tools like ST-Link Utility, STM32CubeProgrammer, or openocd:

bash

openocd -f interface/stlink.cfg -f target/stm32f1x.cfg

Check for expected Device ID: 0x410 ([STM32F103](https://www.ampheo.com/search/STM32F103)).

**3. Internal Differences**
**Die Shots (advanced):**

* Real ST chips use ARM's standard core and peripheral layout.
* Fakes like CS32 or [GD32](https://www.ampheo.com/search/GD32) often have different die architecture (faster cores or different behavior).

**Speed Testing:**

GD32 chips tend to perform better in some benchmarks (due to different Flash technology), but are not [STM32](https://www.ampheo.com/search/STM32)-compatible at the binary level.

**4. Source Matters**
**Buy from trusted sources:**

Digi-Key, Mouser, Arrow, Farnell, or ST-approved distributors.

**Avoid:**

* Unknown eBay or AliExpress sellers offering bulk "blue pill" boards for very low prices.
* These often contain CS32F103C8T6, GD32F103C8T6, or mislabeled ICs.

**5. Community Reports**
Known counterfeits often:

* Misreport memory size.
* Crash when using certain peripherals (e.g. USB CDC, CAN, or ADC with DMA).
* Require different ST-Link firmware or won’t work in STM32CubeMX-generated projects.

Use online databases:

* EEVblog Forum
* GitHub discussions on "fake STM32" detection
* Reddit threads on /r/stm32 or /r/embedded

**Quick Testing Tools**