STM32 F4 Cortex™-M4 MCUs STMicroelectronics STM32 F4 32-bit Cortex™-M4 Microcontrollers (MCUs) offer better performance, DSP capability, more SRAM, and peripheral improvements such as full-duplex I²S, less than 1μA RTC, and 2.4MSPS ADCs. These MCUs include a floating-point unit and core features such as built-in single-cycle multiply-accumulate (MAC) instructions, optimized SIMD arithmetic, and saturating arithmetic instructions.