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TM4C1290NCPDT: Facing an issue with the pll clock and the fvco

Annkathrin Bauer
Prodigy 10 points
Part Number: TM4C1290NCPDT
Other Parts Discussed in Thread: TM4C1294NCPDT

Hello,

We are facing an issue with the pll clock and the fvco within the TM4C129NCPDT.

We cannot run at vco 480 Mhz and Pll / Sysclk at 120 Mhz which are the max as shown in the table of TM4C1294NCPDT__DS__2014-06-18__SPMS433B.

TM4C1294NCPDT__DS__2014-06-18__SPMS433B is from 2014 are there some newer datasheets? The Sysclk will not run faster than 25 Mhz.

We are using the Tiva C Series TM4C129 Connected Launchpad evaluation kit.

This video shows also different values and equation to calculate the pll and sysclk https://www.ti.com/video/3881419229001#tab-1

Which equation is now correct? Can you tell me? We are not using any TI lib or code, so we need to know how it works.

Thank you.

  • 0
    TI__Guru**** 190806 points

    Hi, First of all, please be aware for TM4C129, you must use SysCtlClockFreqSet(). The SysCtlClockSet() API is only for TM4C123. 

    Annkathrin Bauer said:
    We are not using any TI lib or code, so we need to know how it works.

      I'm not sure your rationale to not use the provided SysCtlClockFreqSet() to configure the System Clock. The SysCtlClockFreqSet() has been fine tuned to address errata. I strongly suggest you at least use SysCtlClockFreqSet() to configure your clock if you plan to develop your own drivers for the rest of peripherals. If you must rewrite your own function to configure the clock, I strongly suggest you at least look at SysCtlClockFreqSet source code in C:\ti\TivaWare_C_Series-2.2.0.295\driverlib\sysctl.c file for reference. Please run one of the TivaWare examples that configures the clock for 120Mhz and you can reference how the API is constructed to achieve the final specified frequency.