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F238377S Launchpad development board - Setting CPU CLK using SYSBIOS

maurywalters
Intellectual 710 points
Other Parts Discussed in Thread: SYSBIOS

I am using SYS BIOS 6.42.3.5

I am having similar problem
On the SYS BIOS boot options screen for clock configuration it shows
OSCCLK = 20Mhz
PLL integer multiplier 1
PLL fractional multiplier 0
Sys Clk divider 2
Computer CPU Freq is 5 MHz

What is the oscillator on the launchpad ?
The sample BIOS apps I run are at about half speed.

In addition I would like to get access to the Low speed clock frequency to use in setting peripheral communication rates (SPI AND UART).
Where (what include file) is the variable for low speed clock frequency?

  • 0
    TI__Mastermind 37985 points
    Have you referring to an existing thread? Which one was that?

    In this thread Gautam Iyer says that the oscillator is 10MHz - e2e.ti.com/.../1626441. I guess that would account for the slow speed of the sample apps. Try changing it to 10MHz and see if that helps.

    I don't see any BIOS API that supplies low speed clock frequency, but you can get CPU frequency using the code below. Low speed clock frequency is by default CPUfreq/4. I don't know if that integer divider can be changed and how.

    #include <xdc/runtime/Types.h>
    #include <ti/sysbios/BIOS.h>
    ...
    Types_FreqHz freq;
    ...
    BIOS_getCpuFreq(&freq); // freq.lo contains CPU freq
  • 0 in reply to Sasha Slijepcevic
    Intellectual 710 points

    Sasha,

    Thanks it was the oscillator setting I just wanted to make sure that was the correct item to change.

    Also I used the BIOS call to get CPU freq and then used access to sysctrl.h data item for CLK_CFG_REGS ClkCfgRegs and I can get/set the low speed clock divisor there.

    Maury