ARMv8M

ARMv8-M is a version of the ARMv8 architecture designed for ARM Cortex-M microcontrollers. It extends the ARMv7-M lineage with improved security, enhanced interrupt handling, and optional performance features suited to energy-constrained embedded systems.

A key feature of ARMv8-M is TrustZone-M, a hardware security extension that enables software to run in distinct secure and non-secure worlds. This supports secure boot, protected cryptographic operations, and safeguarded peripherals. The architecture also provides memory protection through a memory protection unit (MPU) and mechanisms to define secure boundaries, including non-secure callable (NSC) functions that expose selected secure routines to non-secure code. ARMv8-M retains the 32-bit Thumb-2 instruction set and a straightforward exception model designed for real-time operation. The nested vectored interrupt controller (NVIC) remains a central component for efficient interrupt handling, with features intended to reduce latency and improve power management in low-power devices.

ARMv8-M defines two profile levels: ARMv8-M Baseline and ARMv8-M Mainline. The Baseline profile is implemented by Cortex-M23 and emphasizes secure/non-secure separation with a compact feature set. The Mainline profile, implemented by Cortex-M33, adds a broader feature set including optional Floating-Point Unit (FPU) and Digital Signal Processing (DSP) capabilities, larger MPUs, and more extensive security features.

Software support and ecosystem include standard ARM toolchains and middleware such as CMSIS, GCC, LLVM, and Arm Compiler, along with support from popular real-time operating systems. ARMv8-M has been widely adopted in IoT devices, automotive sensors, and consumer electronics where security, deterministic behavior, and low power are priorities.