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# System prepended metadata

title: How are FCM32 compared to STM32?
tags: [stm32]

---

Short take: FCM32 = Flashchip Microelectronics’ STM32-style MCUs. Many parts are pin-compatible with [STM32](https://www.ampheo.com/search/STM32) F0/F1 and boot with similar peripherals, but they are not 1:1 firmware-compatible. Some FCM32 parts even run faster (e.g., 100 MHz “H” variants, “Flash Turbo”), while others change cores/features, so code/clocking need tweaks. 
![Flashchip-Microelectronics-FCM32-development-board](https://hackmd.io/_uploads/rJ5fwQICel.jpg)

**How they compare**

**Compatibility**

* Pins/Packages: Often drop-in for popular [STM32F0](https://www.ampheo.com/search/STM32F0)/F1 packages. 
* Registers/Peripherals: Close but differences exist (e.g., power/VBAT options, oscillator behavior, IDs). Flashchip provides a migration guide for F1→FCM32(H) that highlights changes. Expect to touch startup, clock tree, flash wait-states, and a few peripheral regs. 
* Real-world quirks: People report code that runs on STM32/[GD32](https://www.ampheo.com/search/GD32) failing on some FCM32 (e.g., LSI oscillator). Re-validate. 

**Performance**

Some FCM32 “H” parts clock higher than STM32F0 (up to ~100 MHz) and advertise faster flash (“Flash Turbo”). Certain F103-class FCM32s use a Cortex-M4 at 72 MHz vs [STM32F103](https://www.ampheo.com/search/STM32F103)’s M3. 

**Ecosystem & tools**

* STM32: Massive ecosystem (CubeMX/CubeIDE, HAL/LL, middleware, community). 
* FCM32: Smaller community, docs sometimes Chinese-only; you can still use standard Arm toolchains (GCC/Keil/IAR). Plan extra time for bring-up. 

**Cost/availability**

FCM32 shows attractive pricing and availability (e.g., low-cost [dev boards](https://www.onzuu.com/category/development-boards-kits-programmers)). Useful as supply-chain alternates—but budget engineering time for porting. 

**When to pick which**

* Choose [STM32](https://www.ampheoelec.de/search/STM32) if you want the broadest libraries, middleware, examples, and long-term ecosystem support. 
* Consider FCM32 if you need pin-compatible replacements or higher clocks at low cost and can retest/adjust firmware per the migration guide. 

**Porting checklist (firmware)**

* Use CMSIS types and abstract drivers; avoid hardcoding STM32-only register fields.
* Rework clock init (HSI/LSI/LSE ranges, PLL limits), verify flash latency & “Flash Turbo” settings. 
* Re-verify timers, WDT, ADC, UART init values; check interrupt vectors and unique-ID addresses.
* Run a peripheral smoke test (GPIO/timers/UART/SPI/I2C/ADC) and specifically test LSI/LSE if you use RTC/WDT (known divergence). 