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System clock set!

Happy Smile
Intellectual 635 points 
//
// Setup the system clock to run at 40 Mhz from PLL with crystal reference
//

ROM_SysCtlClockSet(SYSCTL_SYSDIV_5 | SYSCTL_USE_PLL | SYSCTL_XTAL_16MHZ |
SYSCTL_OSC_MAIN);

I read the Tivaware document, but i still dont understand how to use that function to get the desired clock frequency




  • 0
    TI__Guru**** 244400 points

    Hello Happy Smile,

    Please look at the Table 5.4 and 5.5 which explains how the System Clock Frequency is derived for PLL w.r.t to the SYSCTL_SYSDIV_x

    But to still explain it the PLL is locked at a fixed frequency based on the XTAL Frequency. The fixed frequency on TM4C123 is not user programmable. The divider value is then used to derive the System Clock. The fixed frequency is 400MHz which is then divided to 200MHz and any further System Divider settings applied

    Regards

    Amit