SYSBIOS setting frequency

Taka,

If a configuration contained the following statements, the net result of these equivalent settings
would be to configure the CPU speed to be 400MHz (the SYS/BIOS 6 setting).

For DSP/BIOS 5
bios.GBL.CLKOUT = 500;

For SYS/BIOS 6
xdc.global.BIOS = xdc.useModule('ti.sysbios.BIOS");
BIOS.cpuFreq = 400;

You can get the CPU clock using C API call
BIOS_getCpuFreq(&cpuFreq);
BIOS_setCpuFreq(&cpuFreq);

Hi, Pubesh-san

Thank you for your reply.

I just wanted to ask you the behavior.
When the setting CPU frequency by PLL and the setting BIOS clkout  value are different, there is any problem?

- SYSBIOS setting frequency  value =  300MHz
                       cpuFreq.lo is 300000000   (by BIOS_getCpuFreq(&cpuFreq)
- C6747 CPU Frequency by CLKIN and PLL module = 456MHz   

In this situation,I think BIOS's Tick is a few time fast. 
Anything else?  For example, CPU Load Graph is not correct?

Best Reagards

-Taka

Taka-san,

When you use DSPBIOS or SYSBIOS, the GBL_setFrequency does not affect the PLL, and therefore has no effect on the actual frequency at which the DSP is running. It is used only to make DSP/BIOS aware of the DSP frequency you are using. This function sets the value of the CPU frequency known to DSP/BIOS. The frequency must be an integer number of KHz.

I hope you know the PLL initialization routines. Why  and how configure this. The initialization of the PLL controller should be performed as soon as possible at the beginning of the program, before initializing any peripherals.
Please see the device-specific data manual for the uses of the PLL controller inputs and outputs.

Pubesh -san,

Thank you for the reply.

Pubesh said:

Taka-san,

When you use DSPBIOS or SYSBIOS, the GBL_setFrequency does not affect the PLL, and therefore has no effect on the actual frequency at which the DSP is running. It is used only to make DSP/BIOS aware of the DSP frequency you are using. This function sets the value of the CPU frequency known to DSP/BIOS. The frequency must be an integer number of KHz.

I hope you know the PLL initialization routines. Why  and how configure this. The initialization of the PLL controller should be performed as soon as possible at the beginning of the program, before initializing any peripherals.
Please see the device-specific data manual for the uses of the PLL controller inputs and outputs.

Of course, I know that. What I wanted to know,
when setting GBL_setFrequency wrong, then what will happen?

 I should fix this mistake setting of course. Before that, I want to know what kind of problem this had

Best Regards,
-Taka

Oh! I realized that I was wrong.
I understood GBL_setFrequency does not actually the Timer clock speed and setting. It's fixed to 24MHz by default.....

Thank you for your great help.

Best Regards,
-Taka