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Anyone knows how to set the core clock at 120MHz with keil on the FRDM-K64F?

Julio Enrique Fajardo

I try with this code

  MCG -> C1 = 0x2AU;

  MCG -> C2 = 0x20U;

  MCG -> C4 = 0x00U;

  MCG -> C5 = 0x09U;

  MCG -> C6 = 0x58U;

  MCG -> SC = 0x00U;

  OSC -> CR = 0x80;

  SIM -> SOPT1 = 0x000C0000UL;

  SIM -> SOPT2 = 0x00010000UL;

  SIM -> CLKDIV1 = 0x01140000UL;

but when i am debugging, after SystemCoreClockUpdate(), i get SystemCoreClock = 192 000 000

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  • 0 Arm Employee Badge in reply to Julio Enrique Fajardo

    Hi

    Looking at the system file I see this:

       3 ... Multipurpose Clock Generator (MCG) in PLL Engaged External (PEE) mode

             Reference clock source for MCG module is an external crystal 8MHz

             Core clock = 120MHz, BusClock = 60MHz

    I look at the schematic for this board and do not see an 8 MHz crystal.  25 and 32K only....

    Does this need to be added ?  Perhaps to pin 51 XTAL_K64_MAIN ?  I see a R74 too -

    Bob

Reply
  • 0 Arm Employee Badge in reply to Julio Enrique Fajardo

    Hi

    Looking at the system file I see this:

       3 ... Multipurpose Clock Generator (MCG) in PLL Engaged External (PEE) mode

             Reference clock source for MCG module is an external crystal 8MHz

             Core clock = 120MHz, BusClock = 60MHz

    I look at the schematic for this board and do not see an 8 MHz crystal.  25 and 32K only....

    Does this need to be added ?  Perhaps to pin 51 XTAL_K64_MAIN ?  I see a R74 too -

    Bob

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