File content as of revision 6:554f0a4b681b:

/*
** ###################################################################
**     Processor:           MKL25Z128VLK4
**     Compilers:           ARM Compiler
**                          Freescale C/C++ for Embedded ARM
**                          GNU C Compiler
**                          IAR ANSI C/C++ Compiler for ARM
**
**     Reference manual:    KL25RM, Rev.1, Jun 2012
**     Version:             rev. 1.1, 2012-06-21
**
**     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: 2012 Freescale Semiconductor, Inc. All Rights Reserved.
**
**     http:                 www.freescale.com
**     mail:                 support@freescale.com
**
**     Revisions:
**     - rev. 1.0 (2012-06-13)
**         Initial version.
**     - rev. 1.1 (2012-06-21)
**         Update according to reference manual rev. 1.
**
** ###################################################################
*/

/**
 * @file MKL25Z4
 * @version 1.1
 * @date 2012-06-21
 * @brief Device specific configuration file for MKL25Z4 (implementation 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.
 */

#include <stdint.h>
#include "MKL25Z4.h"

//MODIFICATION: We DO want watchdog, uC default after reset is enabled with timeout=1024ms (2^10*LPO=1KHz)
//#define DISABLE_WDOG    1

#define CLOCK_SETUP     1
/* Predefined clock setups
   0 ... Multipurpose Clock Generator (MCG) in FLL Engaged Internal (FEI) mode
         Reference clock source for MCG module is the slow internal clock source 32.768kHz
         Core clock = 41.94MHz, BusClock = 13.98MHz
   1 ... Multipurpose Clock Generator (MCG) in PLL Engaged External (PEE) mode
         Reference clock source for MCG module is an external crystal 8MHz
         Core clock = 48MHz, BusClock = 24MHz
   2 ... Multipurpose Clock Generator (MCG) in Bypassed Low Power External (BLPE) mode
         Core clock/Bus clock derived directly from an external crystal 8MHz with no multiplication
         Core clock = 8MHz, BusClock = 8MHz
   3 ... Multipurpose Clock Generator (MCG) in FLL Engaged External (FEE) mode
         Reference clock source for MCG module is an external crystal 32.768kHz
         Core clock = 47.97MHz, BusClock = 23.98MHz
         This setup sets the RTC to be driven by the MCU clock directly without the need of an external source.
         RTC register values are retained when MCU is reset although there will be a slight (mSec's)loss of time
         accuracy durring the reset period. RTC will reset on power down. 
*/

/*----------------------------------------------------------------------------
  Define clock source values
 *----------------------------------------------------------------------------*/
#if (CLOCK_SETUP == 0)
    #define CPU_XTAL_CLK_HZ                 8000000u /* Value of the external crystal or oscillator clock frequency in Hz */
    #define CPU_INT_SLOW_CLK_HZ             32768u   /* Value of the slow internal oscillator clock frequency in Hz  */
    #define CPU_INT_FAST_CLK_HZ             4000000u /* Value of the fast internal oscillator clock frequency in Hz  */
    #define DEFAULT_SYSTEM_CLOCK            41943040u /* Default System clock value */
#elif (CLOCK_SETUP == 1)
    #define CPU_XTAL_CLK_HZ                 8000000u /* Value of the external crystal or oscillator clock frequency in Hz */
    #define CPU_INT_SLOW_CLK_HZ             32768u   /* Value of the slow internal oscillator clock frequency in Hz  */
    #define CPU_INT_FAST_CLK_HZ             4000000u /* Value of the fast internal oscillator clock frequency in Hz  */
    #define DEFAULT_SYSTEM_CLOCK            48000000u /* Default System clock value */
#elif (CLOCK_SETUP == 2)
    #define CPU_XTAL_CLK_HZ                 8000000u /* Value of the external crystal or oscillator clock frequency in Hz */
    #define CPU_INT_SLOW_CLK_HZ             32768u   /* Value of the slow internal oscillator clock frequency in Hz  */
    #define CPU_INT_FAST_CLK_HZ             4000000u /* Value of the fast internal oscillator clock frequency in Hz  */
    #define DEFAULT_SYSTEM_CLOCK            8000000u /* Default System clock value */
#elif (CLOCK_SETUP == 3)    
    #define CPU_XTAL_CLK_HZ                 32768u   /* Value of the external crystal or oscillator clock frequency in Hz */
    #define CPU_INT_SLOW_CLK_HZ             32768u   /* Value of the slow internal oscillator clock frequency in Hz  */
    #define CPU_INT_FAST_CLK_HZ             4000000u /* Value of the fast internal oscillator clock frequency in Hz  */
    #define DEFAULT_SYSTEM_CLOCK            47972352u /* Default System clock value */       
#endif /* (CLOCK_SETUP == 3) */

/* ----------------------------------------------------------------------------
   -- Core clock
   ---------------------------------------------------------------------------- */

//MODIFICATION: That vartiable already exists
// uint32_t SystemCoreClock = DEFAULT_SYSTEM_CLOCK;

/* ----------------------------------------------------------------------------
   -- SystemInit()
   ---------------------------------------------------------------------------- */

void $Sub$$SystemInit (void) {
    
    //MODIFICATION:
    // That variable already exists, we set it here
    SystemCoreClock = DEFAULT_SYSTEM_CLOCK;
    // We want visual indication of boot time with red LED on
    //TODO

#if (DISABLE_WDOG)
  /* Disable the WDOG module */
  /* SIM_COPC: COPT=0,COPCLKS=0,COPW=0 */
  SIM->COPC = (uint32_t)0x00u;
#endif /* (DISABLE_WDOG) */
#if (CLOCK_SETUP == 0)
  /* SIM->CLKDIV1: OUTDIV1=0 */
  SIM->CLKDIV1 = (uint32_t)0x00020000UL; /* Update system prescalers */
  /* Switch to FEI Mode */
  /* MCG->C1: CLKS=0,FRDIV=0,IREFS=1,IRCLKEN=1,IREFSTEN=0 */
  MCG->C1 = (uint8_t)0x06U;
  /* MCG_C2: LOCRE0=0, =0,RANGE0=0,HGO0=0,EREFS0=0,LP=0,IRCS=0 */
  MCG->C2 = (uint8_t)0x00U;
  /* MCG->C4: DMX32=0,DRST_DRS=1 */
  MCG->C4 = (uint8_t)((MCG->C4 & (uint8_t)~(uint8_t)0xC0U) | (uint8_t)0x20U);
  /* OSC0->CR: ERCLKEN=1,=0,EREFSTEN=0,=0,SC2P=0,SC4P=0,SC8P=0,SC16P=0 */
  OSC0->CR = (uint8_t)0x80U;
  /* MCG->C5: =0,PLLCLKEN0=0,PLLSTEN0=0,PRDIV0=0 */
  MCG->C5 = (uint8_t)0x00U;
  /* MCG->C6: LOLIE0=0,PLLS=0,CME0=0,VDIV0=0 */
  MCG->C6 = (uint8_t)0x00U;
  while((MCG->S & MCG_S_IREFST_MASK) == 0x00U) { /* Check that the source of the FLL reference clock is the internal reference clock. */
  }
  while((MCG->S & 0x0CU) != 0x00U) {    /* Wait until output of the FLL is selected */
  }
#elif (CLOCK_SETUP == 1)
  /* SIM->SCGC5: PORTA=1 */
  SIM->SCGC5 |= (uint32_t)0x0200UL;     /* Enable clock gate for ports to enable pin routing */
  /* SIM->CLKDIV1: OUTDIV1=1,OUTDIV4=1 */
  SIM->CLKDIV1 = (uint32_t)0x10010000UL; /* Update system prescalers */
  /* PORTA->PCR18: ISF=0,MUX=0 */
  PORTA->PCR[18] &= (uint32_t)~0x01000700UL;
  /* PORTA->PCR19: ISF=0,MUX=0 */
  PORTA->PCR[19] &= (uint32_t)~0x01000700UL;
  /* Switch to FBE Mode */
  /* OSC0->CR: ERCLKEN=1,EREFSTEN=0,SC2P=1,SC4P=0,SC8P=0,SC16P=1 */
  OSC0->CR = (uint8_t)0x89U;
  /* MCG->C2: LOCRE0=0, RANGE0=2,HGO0=0,EREFS0=1,LP=0,IRCS=0 */
  MCG->C2 = (uint8_t)0x24U;
  /* MCG->C1: CLKS=2,FRDIV=3,IREFS=0,IRCLKEN=1,IREFSTEN=0 */
  MCG->C1 = (uint8_t)0x9AU;
  /* MCG->C4: DMX32=0,DRST_DRS=0 */
  MCG->C4 &= (uint8_t)~(uint8_t)0xE0U;
  /* MCG->C5: PLLCLKEN0=0,PLLSTEN0=0,PRDIV0=1 */
  MCG->C5 = (uint8_t)0x01U;
  /* MCG->C6: LOLIE0=0,PLLS=0,CME0=0,VDIV0=0 */
  MCG->C6 = (uint8_t)0x00U;
  while((MCG->S & MCG_S_IREFST_MASK) != 0x00U) { /* Check that the source of the FLL reference clock is the external reference clock. */
  }
  while((MCG->S & 0x0CU) != 0x08U) {    /* Wait until external reference clock is selected as MCG output */
  }
  /* Switch to PBE Mode */
  /* MCG->C6: LOLIE0=0,PLLS=1,CME0=0,VDIV0=0 */
  MCG->C6 = (uint8_t)0x40U;
  while((MCG->S & 0x0CU) != 0x08U) {    /* Wait until external reference clock is selected as MCG output */
  }
  while((MCG->S & MCG_S_LOCK0_MASK) == 0x00U) { /* Wait until locked */
  }
  /* Switch to PEE Mode */
  /* MCG->C1: CLKS=0,FRDIV=3,IREFS=0,IRCLKEN=1,IREFSTEN=0 */
  MCG->C1 = (uint8_t)0x1AU;
  while((MCG->S & 0x0CU) != 0x0CU) {    /* Wait until output of the PLL is selected */
  }
#elif (CLOCK_SETUP == 2)
  /* SIM->SCGC5: PORTA=1 */
  SIM->SCGC5 |= (uint32_t)0x0200UL;     /* Enable clock gate for ports to enable pin routing */
  /* SIM->CLKDIV1: OUTDIV1=0,OUTDIV4=0 */
  SIM->CLKDIV1 = (uint32_t)0x00000000UL; /* Update system prescalers */
  /* PORTA->PCR18: ISF=0,MUX=0 */
  PORTA->PCR[18] &= (uint32_t)~0x01000700UL;
  /* PORTA->PCR19: ISF=0,MUX=0 */
  PORTA->PCR[19] &= (uint32_t)~0x01000700UL;
  /* Switch to FBE Mode */
  /* OSC0->CR: ERCLKEN=1,EREFSTEN=0,SC2P=1,SC4P=0,SC8P=0,SC16P=1 */
  OSC0->CR = (uint8_t)0x89U;
  /* MCG->C2: LOCRE0=0,RANGE0=2,HGO0=0,EREFS0=1,LP=0,IRCS=0 */
  MCG->C2 = (uint8_t)0x24U;
  /* MCG->C1: CLKS=2,FRDIV=3,IREFS=0,IRCLKEN=1,IREFSTEN=0 */
  MCG->C1 = (uint8_t)0x9AU;
  /* MCG->C4: DMX32=0,DRST_DRS=0 */
  MCG->C4 &= (uint8_t)~(uint8_t)0xE0U;
  /* MCG->C5: PLLCLKEN0=0,PLLSTEN0=0,PRDIV0=0 */
  MCG->C5 = (uint8_t)0x00U;
  /* MCG->C6: LOLIE0=0,PLLS=0,CME0=0,VDIV0=0 */
  MCG->C6 = (uint8_t)0x00U;
  while((MCG->S & MCG_S_IREFST_MASK) != 0x00U) { /* Check that the source of the FLL reference clock is the external reference clock. */
  }
  while((MCG->S & 0x0CU) != 0x08U) {    /* Wait until external reference clock is selected as MCG output */
  }
  /* Switch to BLPE Mode */
  /* MCG->C2: LOCRE0=0,RANGE0=2,HGO0=0,EREFS0=1,LP=1,IRCS=0 */
  MCG->C2 = (uint8_t)0x26U;
  while((MCG->S & 0x0CU) != 0x08U) {    /* Wait until external reference clock is selected as MCG output */
  }
#elif (CLOCK_SETUP == 3)  
/* SIM->SCGC5: PORTA=1 */
  SIM->SCGC5 |= SIM_SCGC5_PORTA_MASK;   /* Enable clock gate for ports to enable pin routing */
  /* SIM->CLKDIV1: OUTDIV1=0, OUTDIV4=1 */
  SIM->CLKDIV1 = (SIM_CLKDIV1_OUTDIV1(0x00) | SIM_CLKDIV1_OUTDIV4(0x01)); /* Update system prescalers */
  /* PORTA->PCR[3]: ISF=0,MUX=0 */
  PORTA->PCR[3] &= (uint32_t)~(uint32_t)((PORT_PCR_ISF_MASK | PORT_PCR_MUX(0x07)));
  /* PORTA->PCR[4]: ISF=0,MUX=0 */
  PORTA->PCR[4] &= (uint32_t)~(uint32_t)((PORT_PCR_ISF_MASK | PORT_PCR_MUX(0x07)));
  /* Switch to FEE Mode */
  /* MCG->C2: LOCRE0=0,RANGE0=0,HGO0=0,EREFS0=1,LP=0,IRCS=0 */
  MCG->C2 = (MCG_C2_RANGE0(0x00) | MCG_C2_EREFS0_MASK);
  /* OSC0->CR: ERCLKEN=1,EREFSTEN=0,SC2P=0,SC4P=0,SC8P=0,SC16P=0 */
  OSC0->CR = OSC_CR_ERCLKEN_MASK | OSC_CR_SC16P_MASK | OSC_CR_SC4P_MASK | OSC_CR_SC2P_MASK;
  /* MCG->C1: CLKS=0,FRDIV=0,IREFS=0,IRCLKEN=1,IREFSTEN=0 */
  MCG->C1 = (MCG_C1_CLKS(0x00) | MCG_C1_FRDIV(0x00) | MCG_C1_IRCLKEN_MASK);
  /* MCG->C4: DMX32=1,DRST_DRS=1 */
  MCG->C4 = (uint8_t)((MCG->C4 & (uint8_t)~(uint8_t)(
            MCG_C4_DRST_DRS(0x02)
           )) | (uint8_t)(
            MCG_C4_DMX32_MASK |
            MCG_C4_DRST_DRS(0x01)
           ));
  while((MCG->S & MCG_S_IREFST_MASK) != 0x00U) { /* Check that the source of the FLL reference clock is the external reference clock. */
  }
  while((MCG->S & 0x0CU) != 0x00U) {    /* Wait until output of the FLL is selected */
  }          
#endif /* (CLOCK_SETUP == 3) */
}