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Compiler/TM4C1290NCPDT: How programmatically I can find out what is my system clock frequency

Sergey uskach
Intellectual 690 points
Part Number: TM4C1290NCPDT

Tool/software: TI C/C++ Compiler

I am pretty new for TI  and would like to find out how I can find out what is my clock frequency ?

Which API call is for it ?

Thanks

  • 0
    Guru 117855 points

    I'm unsure if an API call exists - yet you can (always) set up one of the MCU's Timers to provide a 'Frequency Scaled Replica' of the System Clock - and output that.   (staff suggests a 'Divide by 8' - which would produce an 'Easily Measured' 15MHz (should your system clock be set to MAX [120MHz] ) - and add no (disturbance) to your (assumed) external oscillator components.)

    Note: Pay (very) special attention to the System Control Clock/Frequency Set Command.   Getting that wrong will, 'Lock you Out' from the MCU!    (there are many examples - be sure to search/find/comply!)

  • 0
    TI__Guru**** 190806 points

    Hi Sergey,

      Please reference any of the TivaWare examples under <TivaWare_Installation>/examples/boards/ek_tm4c1294xl/. Start with the hell/hell.c example and you will find the API as shown below to configure the system clock frequency and return the clock frequency to g_ui32SysClock which you can later use in your application.

        //
    // Run from the PLL at 120 MHz.
    //
    g_ui32SysClock = MAP_SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ |
                SYSCTL_OSC_MAIN | SYSCTL_USE_PLL |
                SYSCTL_CFG_VCO_480), 120000000);
  • 0 in reply to cb1_mobile
    Guru 117855 points

    May we note, 'A dagger to the heart' of what was believed to be a highly advantaged & earlier arriving (first arriving) suggestion!    

    Nothing can compete w/a 'Direct & Real, Observable (and Measurable) Frequency Output' - which may (often) prove of value - on its own!    (as it may serve as the precise frequency source for other board devices.)   

    Relying (only) upon (pardon) 'overly complex' software - which involves multiple, inter-related parameters for correctness - is not always judged as effective.   Simply review the length, depth & extent of (both) of those  (near endless) API Calls - and then note 'How Many here' have been forced to 'Call for Help!.' 

    Regulatory Agencies (properly) 'frown upon' such highly tasked, 'Software Only' approaches.     And - what happens should (any) of your external oscillator components prove 'out of spec', or mislabeled, or 'drift' - or otherwise age and/or become 'inaccurate.'    (I believe the software calls vendor suggested to be unable to detect such issues - and to (improperly) report, 'ALL is WELL!)     When in fact - it is not!

    Such weakness could have been (properly & convincingly) detected  -  via the far more robust & simpler hardware/abbreviated software method (which proves more direct & vastly simpler/shorter - exercising basic MCU Timer software API).

    Pity that such 'multi-advantaged method' (was) dismissed/kicked to the curb...