CMSIS-CORE implements the basic run-time system for a Cortex-M device and gives the user access to the processor core and the device peripherals. In detail it defines:

Hardware Abstraction Layer (HAL) for Cortex-M processor registers with standardized definitions for the SysTick, NVIC, System Control Block registers, MPU registers, FPU registers, and core access functions.
System exception names to interface to system exceptions without having compatibility issues.
Methods to organize header files that makes it easy to learn new Cortex-M microcontroller products and improve software portability. This includes naming conventions for device-specific interrupts.
Methods for system initialization to be used by each MCU vendor. For example, the standardized SystemInit() function is essential for configuring the clock system of the device.
Intrinsic functions used to generate CPU instructions that are not supported by standard C functions.
A variable to determine the system clock frequency which simplifies the setup the SysTick timer.

The following sections provide details about the CMSIS-CORE:

Using CMSIS in Embedded Applications describes the project setup and shows a simple program example.
Using TrustZone® for ARMv8-M describes how to use the security extensions available in the ARMv8-M architecture.
CMSIS-Core Device Templates describes the files of the CMSIS-CORE in detail and explains how to adapt template files provided by ARM to silicon vendor devices.
MISRA-C Deviations describes the violations to the MISRA standard.
Reference describe the features and functions of the Device Header File <device.h> in detail.
Data Structures describe the data structures of the Device Header File <device.h> in detail.

CMSIS-CORE in ARM::CMSIS Pack

Files relevant to CMSIS-CORE are present in the following ARM::CMSIS directories:

File/Folder	Content
CMSIS\Documentation\Core	This documentation
CMSIS\Include	CMSIS-CORE header files (for example core_cm3.h, core_cmInstr.h, etc.)
Device	ARM reference implementations of Cortex-M devices
Device\_Template_Vendor	CMSIS-Core Device Templates for extension by silicon vendors

Processor Support

CMSIS supports the complete range of Cortex-M processors (with exception of Cortex-M1) and the ARMv8-M architecture including security extensions.

Cortex-M Reference Manuals

The Cortex-M Reference Manuals are generic user guides for devices that implement the various ARM Cortex-M processors. These manuals contain the programmers model and detailed information about the core peripherals.

Cortex-M0 Devices Generic User Guide (ARMv6-M architecture)
Cortex-M0+ Devices Generic User Guide (ARMv6-M architecture)
Cortex-M3 Devices Generic User Guide (ARMv7-M architecture)
Cortex-M4 Devices Generic User Guide (ARMv7-M architecture)
Cortex-M7 Devices Generic User Guide (ARMv7-M architecture)

Reference manuals for Cortex-M23 and Cortex-M33 where not available at the time of release.

ARMv8-M Architecture

ARMv8-M introduces two profiles Baseline (for power and area constrained applications) and Mainline (full-featured with optional SIMD, floating-point, and co-processor extensions). Both ARMv8-M profiles are supported by CMSIS.

The ARMv8-M Architecture is described in the ARMv8-M Architecture Reference Manual.

Tested and Verified Toolchains

The CMSIS-CORE CMSIS-Core Device Templates supplied by ARM have been tested and verified with the following toolchains:

ARM: ARM Compiler V5.6
ARM: ARM Compiler V6.6 (for Cortex-M23, Cortex-M33, ARMv8-M)
GNU: GNU Tools ARM Embedded 5.4 2016q3
IAR: IAR Embedded Workbench Kickstart Edition V6.10