text: /*
  ** ###################################################################
  **     Compilers:           ARM Compiler
  **                          Freescale C/C++ for Embedded ARM
  **                          GNU C Compiler
  **                          IAR ANSI C/C++ Compiler for ARM
  **
  **     Reference manual:    K21RM, Rev.4, Feb 2013
  **     Version:             rev. 1.4, 2013-01-24
  **
  **     Abstract:
  **         Provides a system configuration function and a global variable that
  **         contains the system frequency. It configures the device and initializes
  **         the oscillator (PLL) that is part of the microcontroller device.
  **
  **     Copyright: 2013 Freescale, Inc. All Rights Reserved.
  **
  **     http:                 www.freescale.com
  **     mail:                 support@freescale.com
  **
  **     Revisions:
  **     - rev. 1.0 (2012-06-06)
  **         Initial public version.
  **     - rev. 1.1 (2012-07-31)
  **         Fixed address of SIM_SDID register.
  **     - rev. 1.2 (2012-08-29)
  **         Update to Rev. 3 of reference manual.
  **         Updated UART0 and CRC register definition.
  **         VREF module definition removed.
  **     - rev. 1.3 (2012-10-11)
  **         PDB module update - PDB0_PO1DLY register added.
  **     - rev. 1.4 (2013-01-24)
  **         Update to Rev. 4 of reference manual.
  **
  ** ###################################################################
  */
  
  /**
   * @file MK21D5
   * @version 1.4
   * @date 2013-01-24
   * @brief Device specific configuration file for MK21D5 (header file)
   *
   * Provides a system configuration function and a global variable that contains
   * the system frequency. It configures the device and initializes the oscillator
   * (PLL) that is part of the microcontroller device.
   */
  
  #ifndef SYSTEM_MK21D5_H_
  #define SYSTEM_MK21D5_H_                         /**< Symbol preventing repeated inclusion */
  
  #ifdef __cplusplus
  extern "C" {
  #endif
  
  #include <stdint.h>
  
      /**
       * @brief System clock frequency (core clock)
       *
       * The system clock frequency supplied to the SysTick timer and the processor
       * core clock. This variable can be used by the user application to setup the
       * SysTick timer or configure other parameters. It may also be used by debugger to
       * query the frequency of the debug timer or configure the trace clock speed
       * SystemCoreClock is initialized with a correct predefined value.
       */
      extern uint32_t SystemCoreClock;
  
      /**
       * @brief Setup the microcontroller system.
       *
       * Typically this function configures the oscillator (PLL) that is part of the
       * microcontroller device. For systems with variable clock speed it also updates
       * the variable SystemCoreClock. SystemInit is called from startup_device file.
       */
      void SystemInit (void);
  
      /**
       * @brief Updates the SystemCoreClock variable.
       *
       * It must be called whenever the core clock is changed during program
       * execution. SystemCoreClockUpdate() evaluates the clock register settings and calculates
       * the current core clock.
       */
      void SystemCoreClockUpdate (void);
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif  /* #if !defined(SYSTEM_MK21D5_H_) */
  