ARM is the most ubiquitous reference design supplier in the embedded market, with more than 10 billion ARM-based microcontrollers produced for embedded applications. One of the most interesting core designs in the embedded industry is the ARM Cortex-M family, which includes a range of models scaling from cost-effective and energy-efficient, to high-performance cores specifically designed for multimedia microcontrollers. Despite ranging among three different instruction sets (ARMv6, ARMv7 and ARMv8), all Cortex-M CPUs share the same programming interface, which improves portability across microcontrollers in the same families.

Most of the examples in this book will be based on this family of CPUs. Though most of the concepts expressed will be applicable to other core designs as well, picking a reference platform now opens the door to a more complete analysis of the interactions with the underlying hardware. In particular, some of the examples in this book use specific assembly instructions from the ARMv7 instruction set, which is implemented in some Cortex-M CPU cores.