# CMSIS Version History

This document describes the changes between the different CMSIS versions.

Version: 2.10 - July 2011

Information in this file, the accompany manuals, and software is
Copyright © ARM Ltd.
All rights reserved.

## Contents

1. Used Toolchains
2. Changes to version V2.00
3. Changes to version V1.30
4. Changes to version V1.20
5. Open Points
6. Limitations

## Used Toolchains

Following toolchains have been used for test / verification:.

- ARM: MDK-ARM Version 4.21
- GNU: Sourcery G++ Lite Edition for ARM 2010.09-51
- IAR: IAR Embedded Workbench Kickstart Edition V6.10

## Changes to version V2.00

### Added CMSIS DSP Software Library support for Cortex-M0 based MCUs

The CMSIS DSP Software Library provides now also libraries and examples for Cortex-M0.

For more information refer to CMSIS DSP Library documentation.

### Added big endian support for DSP library

The CMSIS DSP Software Library provides now also pre-build libraries and projects for big endian devices.

For more information refer to CMSIS DSP Library documentation.

### Simplified folder structure for CMSIS include files

All CMSIS core include files as well as the DSP-Library header files are located in a single folder ./CMSIS/Include.

### Changed folder structure for Device Support packages

Device Support packages are expected to be in folder ./Device located at the same level as ./CMSIS.

The new Device folder contains the following subfolders:

- Device

- <Vendor>
  - <Device> | <Device Series>
    - Include
      <device>.h
      system_<device>.h
    - Source
      - Templates
        system_<device>.c
        - <Toolchain>
          startup_<device>.s
        - <Toolchain>
        - ...
  - <Device> | <Device Series>
  - ...
- <Vendor>
- ...

Template files are application specific files and are required to be copied to the project prior to use!

### Removed CMSIS core source files

The CMSIS core source files core_cm0.c, core_cm3.c, core_cm4.c containing helper functions for older ARM compiler versions got removed.

For the ARM Compiler Toolchain version V4.0.677 or later is required!

## Changes to version V1.30

### Added CMSIS DSP Software Library

The CMSIS DSP Software Library is a suite of common signal processing functions targeted to Cortex-M processor based microcontrollers. Even though the code has been specifically optimized towards using the extended DSP instruction set of the Cortex-M4 processor, the library can be compiled for any Cortex-M processor.

For more information see CMSIS DSP Library documentation.

### Added CMSIS System View Description

The CMSIS System View Description answers the challenges of accurate, detailed and timely device aware peripheral debugging support for Cortex Microcontroller based devices by the software development tools vendor community.

Silicon vendors shall create and maintain a formalized description of the debug view for all the peripherals contained in their Cortex Microcontroller based devices. Tool vendors use such descriptions to establish device specific debug support in their debugging tools.

A standardized System View Description shall provide a common approach to capturing peripheral debug related information in a machine readable files.

For more information see CMSIS System View Description.

### Added Cortex-M4 Core Support

Additional folder CM4, containing the Cortex-M4 core support files, has been added.

- CM0
- CM3
- CM4
  - CoreSupport
  - DeviceSupport

### New naming for Core Support Files

The new Core Support Files are:

- core_cm#.h (# = 0, 3, 4)
- core_cmFunc.h (Cortex-M Core Register access functions)
- core_cmInstr.h (Cortex-M Core instructions)
- core_cm4_simd.h (Cortex-M4 SIMD instructions)

## Changes to version V1.20

### Removed CMSIS Middelware packages

CMSIS Middleware is removed and no longer focus of CMSIS.

### SystemFrequency renamed to SystemCoreClock

The variable name SystemCoreClock is more precise than SystemFrequency because the variable holds the clock value at which the core is running.

### Changed startup concept

The old startup concept (calling SystemInit_ExtMemCtl from startup file and calling SystemInit from main) has the weakness that it does not work for controllers which need a already configuerd clock system to configure the external memory controller.

##### Changed startup concept

- SystemInit() is called from startup file before premain.
- SystemInit() configures the clock system and also configures an existing external memory controller.
- SystemInit() must not use global variables.
- SystemCoreClock is initialized with a correct predefined value.
- Additional function void SystemCoreClockUpdate (void) is provided.
  SystemCoreClockUpdate() updates the variable SystemCoreClock and must be called whenever the core clock is changed.
  SystemCoreClockUpdate() evaluates the clock register settings and calculates the current core clock.

### Advanced Debug Functions

ITM communication channel is only capable for OUT direction. To allow also communication for IN direction a simple concept is provided.

- Global variable volatile int ITM_RxBuffer used for IN data.
- Function int ITM_CheckChar (void) checks if a new character is available.
- Function int ITM_ReceiveChar (void) retrieves the new character.

For detailed explanation see file CMSIS debug support.htm.

### Core Register Bit Definitions

Files core_cm3.h and core_cm0.h contain now bit definitions for Core Registers. The name for the defines correspond with the Cortex-M Technical Reference Manual.

e.g. SysTick structure with bit definitions

    /** \brief  Structure type to access the System Timer (SysTick).
     */
    typedef struct
    {
      __IO uint32_t CTRL;                    /*!< Offset: 0x000 (R/W)  SysTick Control and Status Register */
      __IO uint32_t LOAD;                    /*!< Offset: 0x004 (R/W)  SysTick Reload Value Register       */
      __IO uint32_t VAL;                     /*!< Offset: 0x008 (R/W)  SysTick Current Value Register      */
      __I  uint32_t CALIB;                   /*!< Offset: 0x00C (R/ )  SysTick Calibration Register        */
    } SysTick_Type;

    /* SysTick Control / Status Register Definitions */
    #define SysTick_CTRL_COUNTFLAG_Pos         16                                             /*!< SysTick CTRL: COUNTFLAG Position */
    #define SysTick_CTRL_COUNTFLAG_Msk         (1UL << SysTick_CTRL_COUNTFLAG_Pos)            /*!< SysTick CTRL: COUNTFLAG Mask */

    #define SysTick_CTRL_CLKSOURCE_Pos          2                                             /*!< SysTick CTRL: CLKSOURCE Position */
    #define SysTick_CTRL_CLKSOURCE_Msk         (1UL << SysTick_CTRL_CLKSOURCE_Pos)            /*!< SysTick CTRL: CLKSOURCE Mask */

    #define SysTick_CTRL_TICKINT_Pos            1                                             /*!< SysTick CTRL: TICKINT Position */
    #define SysTick_CTRL_TICKINT_Msk           (1UL << SysTick_CTRL_TICKINT_Pos)              /*!< SysTick CTRL: TICKINT Mask */

    #define SysTick_CTRL_ENABLE_Pos             0                                             /*!< SysTick CTRL: ENABLE Position */
    #define SysTick_CTRL_ENABLE_Msk            (1UL << SysTick_CTRL_ENABLE_Pos)               /*!< SysTick CTRL: ENABLE Mask */

    /* SysTick Reload Register Definitions */
    #define SysTick_LOAD_RELOAD_Pos             0                                             /*!< SysTick LOAD: RELOAD Position */
    #define SysTick_LOAD_RELOAD_Msk            (0xFFFFFFUL << SysTick_LOAD_RELOAD_Pos)        /*!< SysTick LOAD: RELOAD Mask */

    /* SysTick Current Register Definitions */
    #define SysTick_VAL_CURRENT_Pos             0                                             /*!< SysTick VAL: CURRENT Position */
    #define SysTick_VAL_CURRENT_Msk            (0xFFFFFFUL << SysTick_VAL_CURRENT_Pos)        /*!< SysTick VAL: CURRENT Mask */

    /* SysTick Calibration Register Definitions */
    #define SysTick_CALIB_NOREF_Pos            31                                             /*!< SysTick CALIB: NOREF Position */
    #define SysTick_CALIB_NOREF_Msk            (1UL << SysTick_CALIB_NOREF_Pos)               /*!< SysTick CALIB: NOREF Mask */

    #define SysTick_CALIB_SKEW_Pos             30                                             /*!< SysTick CALIB: SKEW Position */
    #define SysTick_CALIB_SKEW_Msk             (1UL << SysTick_CALIB_SKEW_Pos)                /*!< SysTick CALIB: SKEW Mask */

    #define SysTick_CALIB_TENMS_Pos             0                                             /*!< SysTick CALIB: TENMS Position */
    #define SysTick_CALIB_TENMS_Msk            (0xFFFFFFUL << SysTick_VAL_CURRENT_Pos)        /*!< SysTick CALIB: TENMS Mask */

    /*@} end of group CMSIS_SysTick */

### DoxyGen Tags

DoxyGen tags in files core_cm3.[c,h] and core_cm0.[c,h] are reworked to create proper documentation using DoxyGen.

### Folder Structure

The folder structure is changed to differentiate the single support packages.

- CM0
- CM3
  - CoreSupport
  - DeviceSupport
  - Vendor
    - Device
      - Startup
        - Toolchain
        - Toolchain
        - ...
    - Device
    - ...
  - Vendor
  - ...
- Example (optional)
  - Toolchain
    - Device
    - Device
    - ...
  - Toolchain
  - ...

- Documentation

## Open Points

Following points need to be clarified and solved:

- Equivalent C and Assembler startup files.

  Is there a need for having C startup files although assembler startup files are very efficient and do not need to be changed?

- Placing of HEAP in external RAM.

  It must be possible to place HEAP in external RAM if the device supports an external memory controller.

- Placing of STACK /HEAP.

  STACK should always be placed at the end of internal RAM.

  If HEAP is placed in internal RAM than it should be placed after RW ZI section.

## Limitations

The following limitations are not covered with the current CMSIS version:

- No C startup files are available.