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RTOS/LAUNCHXL-F28379D: LAUNCHXL-F28379D system clock setup

Fei Pan99
Prodigy 130 points

Part Number: LAUNCHXL-F28379D
Other Parts Discussed in Thread: SYSBIOS

Tool/software: TI-RTOS

Hi all,

I would like to setup the system clock on F28379D launchpad. I would like to understand the difference of the following setup methods (I am using sysbios)

1. In the main function, before Bios_start() is called, call InitSysPll(XTAL_OSC,IMULT_40,FMULT_0,PLLCLK_BY_2). It configs using external oscillator and the system clock is 200 MHz.

2. In the RTOS config file, create the instance of boot and config boot as follows to config system clock as 200 MHz.

BIOS.cpuFreq.lo = 200000000;
Boot.OSCCLK = 10;
Boot.SPLLIMULT = 40;
Boot.SYSCLKDIVSEL = 1;

3. In the project property debug flash setting, config the clock as follows. It seems like I cannot config it at 200 MHz during debug?

  • 0
    TI__Guru 54845 points

    1. InitSysPll() is the standard non-BIOS way to set up the PLL. This is the method I'd recommend using. There's no issue with using it in a SYS/BIOS project--you'll probably just want to make sure that PLL configuration in the Boot module (option 2) is turned off.

    2. The Boot module clock configuration allows SYS/BIOS to configure the PLL as part of its boot init function that is called before main() is reached. Note that BIOS.cpuFreq.lo needs to contain the correct value even if you are using option 1 to configure the PLL. SYS/BIOS uses it to set up its clock tick.

    3. These clock settings are only used for Flash operations like loading the device through CCS. You still need to use option 1 or 2 for when the device is actually running.

    Whitney