Hands-On RTOS with Microcontrollers

Low power

STM's low power line is squarely aimed at battery-powered devices. Here's a quick comparison between all of the different family members:

MCU version	CPU	Description
STM32L	Cortex-M0	Lowest performance and RAM and ROM space of the family, but offers fairly good efficiency.
STM32L1	Cortex-M3	Higher ROM capacity and offers faster performance with the trade-off of increased power consumption.
STM32L4 and STM32L4+	Cortex-M4	Have increased number-crunching capability (the STM32L4+ also offers faster clock speeds and larger internal flash storage).
STM32L5	Cortex-M33	Blends performance and power and incorporates the latest ARM v8 architecture. Cortex-M33 offers additional security features, such ...