RTOS/TM4C1290NCPDT: Where is the system clock being set in example?

Hi Doug,

Find this code line below.

//
// Set the clocking to run directly from the crystal at 120MHz.
//
g_ui32SysClock = MAP_SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ | SYSCTL_OSC_MAIN |  SYSCTL_USE_PLL | SYSCTL_CFG_VCO_480), 120000000);

-kel

Thanks Kel,

1) can you tell me where the documentation for g_ui32SysClk is documented.

2) I'm curious where this is set in the example I mentioned as I'm trying to learn what code is running that I can see and what code is "magically" running from somewhere not intuitive to the casual observer.

Doug

Hi,

The ui32SysClk is the return of MAP_SysCtlClockFreqSet(). You can see more details about this at "SW-TM4C-DRL-UG-2.1.4.178" doc which can be found at "C:\ti\TivaWare_C_Series-2.1.4.178\docs".

ui32SysClk return is "The actual configured system clock frequency in Hz or zero if the value could not be changed due to a parameter error or PLL lock failure."

You can see where the system clock is set at main()

int
main(void)
{
uint32_t ui32TxCount, ui32RxCount, ui32Fullness, ui32SysClock, ui32PLLRate;
tRectangle sRect;
char pcBuffer[16];
#ifdef USE_ULPI
uint32_t ui32Setting;
#endif

//
// Set the system clock to run at 120MHz from the PLL.
//
ui32SysClock = MAP_SysCtlClockFreqSet((SYSCTL_XTAL_25MHZ |
SYSCTL_OSC_MAIN | SYSCTL_USE_PLL |
SYSCTL_CFG_VCO_480), 120000000);

To learn more specifics about System Clock see datasheet under Clock Configuration.

http://www.ti.com/lit/ds/symlink/tm4c129xnczad.pdf

-kel