File content as of revision 98:01a414ca7d6d:

/*
** ###################################################################
**     Compilers:           ARM Compiler
**                          Freescale C/C++ for Embedded ARM
**                          GNU C Compiler
**                          IAR ANSI C/C++ Compiler for ARM
**
**    
**
**     Version:             rev. 2.0, 2012-03-19
**
**     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: 2015 Freescale Semiconductor, Inc. All Rights Reserved.
**
**     http:                 www.freescale.com
**     mail:                 support@freescale.com
**
**     Revisions:
**     - rev. 1.0 (2011-12-15)
**         Initial version
**     - rev. 2.0 (2012-03-19)
**         PDB Peripheral register structure updated.
**         DMA Registers and bits for unsupported DMA channels removed.
**
** ###################################################################
*/

/**
 * @file MK20DX256
 * @version 2.0
 * @date 2012-03-19
 * @brief Device specific configuration file for MK20DX256 (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_MK20DX256_H_
#define SYSTEM_MK20DX256_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_MK20DX256_H_) */