# Overview {#mainpage} The **CMSIS-Core (Cortex-M)** component implements the basic run-time system for Arm Cortex-M devices 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 (Cortex-M): - \ref using_pg explains the project setup and shows a simple program example. \if ARMv8M - \ref using_TrustZone_pg "Using TrustZone® for Armv8-M" describes how to use the security extensions available in the Armv8-M architecture. \endif - \ref cmsis_core_files describes the files of the CMSIS-Core (Cortex-M) in detail and explains how to adapt template files provided by Arm to silicon vendor devices. - \ref coreMISRA_Exceptions_pg describes the violations to the MISRA standard. - [**API Reference**](modules.html) describes the features and functions of the \ref device_h_pg in detail. - [**Data Structures**](annotated.html) describe the data structures of the \ref device_h_pg in detail. ## Access to CMSIS-Core (Cortex-M) CMSIS-Core is actively maintained in the [**CMSIS 6 GitHub repository**](https://github.com/ARM-software/CMSIS_6) and released as part of the [**CMSIS Software Pack**](../General/cmsis_pack.html). The following directories and files relevant to CMSIS-Core (Cortex-M) are present in the **ARM::CMSIS** Pack: Directory | Content :---------------------------------|:------------------------------------------------------------------------ 📂 CMSIS | CMSIS Base software components folder ┣ 📂 Documentation/html/Core | A local copy of this CMSIS-Core (M) documentation â”— 📂 Core | CMSIS-Core files    ┣ 📂 Include | \ref cmsis_processor_files.     â”— 📂 m-profile| Header files specific for Arm M-Profile.
See \ref cmsis_compiler_files and \ref cmsis_feature_files.    â”— 📂 Template | \ref cmsis_template_files ## Processor Support {#ref_v6-v8M} CMSIS-Core supports the complete range of [Cortex-M processors](https://www.arm.com/products/silicon-ip-cpu?families=cortex-m&showall=true). \anchor ref_man_sec **Cortex-M Generic User Guides** Following Cortex-M Device Generic User Guides contain the programmers model and detailed information about the core peripherals: - [Cortex-M0 Devices Generic User Guide (Armv6-M architecture)](https://developer.arm.com/documentation/dui0497/latest/) - [Cortex-M0+ Devices Generic User Guide (Armv6-M architecture)](https://developer.arm.com/documentation/dui0662/latest/) - [Cortex-M3 Devices Generic User Guide (Armv7-M architecture)](https://developer.arm.com/documentation/dui0552/latest/) - [Cortex-M4 Devices Generic User Guide (Armv7-M architecture)](https://developer.arm.com/documentation/dui0553/latest/) - [Cortex-M7 Devices Generic User Guide (Armv7-M architecture)](https://developer.arm.com/documentation/dui0646/latest/) - [Cortex-M23 Devices Generic User Guide (Armv8-M architecture)](https://developer.arm.com/documentation/dui1095/latest/) - [Cortex-M33 Devices Generic User Guide (Armv8-M architecture)](https://developer.arm.com/documentation/100235/latest/) - [Cortex-M52 Devices Generic User Guide (Armv8.1-M architecture)](https://developer.arm.com/documentation/102776/latest/) - [Cortex-M55 Devices Generic User Guide (Armv8.1-M architecture)](https://developer.arm.com/documentation/101273/latest/) - [Cortex-M85 Devices Generic User Guide (Armv8.1-M architecture)](https://developer.arm.com/documentation/101928/latest/) CMSIS-Core also supports the following Cortex-M processor variants: - [Cortex-M1](https://developer.arm.com/Processors/Cortex-M1) is a processor designed specifically for implementation in FPGAs (Armv6-M architecture). - [SecurCore SC000](https://developer.arm.com/Processors/SecurCore%20SC000) is designed specifically for smartcard and security applications (Armv6-M architecture). - [SecurCore SC300](https://developer.arm.com/Processors/SecurCore%20SC300) is designed specifically for smartcard and security applications (Armv7-M architecture). - [Cortex-M35P](https://developer.arm.com/Processors/Cortex-M35P) is a tamper resistant Cortex-M processor with optional software isolation using TrustZone for Armv8-M. - [STAR-MC1](https://www.armchina.com/mountain?infoId=160) is a variant of Armv8-M with TrustZone designed by Arm China. \anchor ARMv8M **Armv8-M and Armv8.1-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 and Armv8.1-M are supported by CMSIS. The Armv8-M architecture is described in the [Armv8-M Architecture Reference Manual](https://developer.arm.com/documentation/ddi0553/latest/). The Armv8.1-M architecture further extends Armv8-M with Helium (the so called M-Profile Vector Extension (MVE)), as well as further instruction set and debug extensions. More information about Armv8.1-M architecture is available under [Arm Helium technology](https://developer.arm.com/Architectures/Helium). ## Tested and Verified Toolchains {#tested_tools_sec} The \ref cmsis_core_files delivered with this CMSIS-Core release have been tested and verified with the following toolchains: - Arm Compiler for Embedded 6.22 - IAR C/C++ Compiler for Arm 9.40 - GNU Arm Embedded Toolchain 13.2.1 - LLVM/Clang 18.3.1