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TMS320F28377S - How to change clock speed

SHUBHAM SUNDEEP
Prodigy 20 points

Other Parts Discussed in Thread: TMS320F28377S, CONTROLSUITE

Part Number: TMS320F28377S

Application: pwm generation

Question type: Development and troubleshooting

Support topic: /Product/Development and troubleshooting/Search the forums for my problem/

Description of the problem: How to know the DSP clock speed and how to change it.
How to configure DSP for 200MHz

  • 0
    TI__Guru 61235 points

    Hello Shubham,

    Please see any of the code examples in ControlSuite for F28377S.  They use a common clock init function found in

    C:\TI\controlSUITE\device_support\F2837xS\v200\F2837xS_common\source

    You can download ControlSuite from the TI web.

    Regards,

    David

  • 0 in reply to David M. Alter
    Prodigy 20 points
    Hello David,
    Thanks for your reply. I have seen the init function, I have also referred technical reference manual to configure cloak at 200Hz. But I can't understand where to make changes in init function.

    Regards,
    Shubham
  • 0 in reply to SHUBHAM SUNDEEP
    TI__Guru 61235 points

    Shubham,

    Look in the C:\TI\controlSUITE\device_support\F2837xS\v200\F2837xS_common\source\F2837xS_SysCtrl.c file, function InitSysCtrl().  The PLL frequency is controlled using passed parameters to the InitSysPll() function.

    //
    // Initialize the PLL control: SYSPLLMULT and SYSCLKDIVSEL.
    //
    // Defined options to be passed as arguments to this function are defined
    // in F2837xS_Examples.h.
    //
    // Note: The internal oscillator CANNOT be used as the PLL source if the
    // PLLSYSCLK is configured to frequencies above 194 MHz.
    //
    //  PLLSYSCLK = (XTAL_OSC) * (IMULT + FMULT) / (PLLSYSCLKDIV)
    //
    #ifdef _LAUNCHXL_F28377S
       InitSysPll(XTAL_OSC,IMULT_40,FMULT_0,PLLCLK_BY_2);
    #else
       InitSysPll(XTAL_OSC,IMULT_20,FMULT_0,PLLCLK_BY_2);
    #endif

    In the code used above, the Launchpad (LAUNCHXL_F28377S) has an on-board 10 MHz crystal (not the internal 10 MHz oscillator).  So, the function call is specifying XTAL_OSC (defined as 1 in F2837xS_Examples.h), IMULT = 40, FMULT=0 (see the TRM for info on IMULT and FMULT bits), and the post divider to /2.  This gives 10*40/2 = 200 MHz.

    Regards,

    David