text: /**************************************************************************//**
      @file     system_ARMCM0.c
      @brief    CMSIS Device System Source File for
               ARMCM0 Device Series
      @version  V2.00
      @date     18. August 2015
   ******************************************************************************/
  /*  Copyright (c) 2011 - 2015 ARM LIMITED
  
      All rights reserved.
      Redistribution and use in source and binary forms, with or without
      modification, are permitted provided that the following conditions are met:
      - Redistributions of source code must retain the above copyright
       notice, this list of conditions and the following disclaimer.
      - Redistributions in binary form must reproduce the above copyright
       notice, this list of conditions and the following disclaimer in the
       documentation and/or other materials provided with the distribution.
      - Neither the name of ARM nor the names of its contributors may be used
       to endorse or promote products derived from this software without
       specific prior written permission.
  
      THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
      AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
      IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
      ARE DISCLAIMED. IN NO EVENT SHALL COPYRIGHT HOLDERS AND CONTRIBUTORS BE
      LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
      CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
      SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
      INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
      CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
      ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
      POSSIBILITY OF SUCH DAMAGE.
      ---------------------------------------------------------------------------*/
  
  
  #include "ARMCM0.h"
  
  /*  ----------------------------------------------------------------------------
      Define clocks
      ----------------------------------------------------------------------------*/
  #define  XTAL            ( 5000000U)      /* Oscillator frequency             */
  
  #define  SYSTEM_CLOCK    (5 * XTAL)
  
  
  /*  ----------------------------------------------------------------------------
      System Core Clock Variable
      ----------------------------------------------------------------------------*/
  uint32_t SystemCoreClock = SYSTEM_CLOCK;  /* System Core Clock Frequency      */
  
  
  void SystemCoreClockUpdate (void)
  {
      SystemCoreClock = SYSTEM_CLOCK;
  }
  
  void SystemInit (void)
  {
      SystemCoreClock = SYSTEM_CLOCK;
  }
  