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OMAPL138 power spreadsheet

Calum Mackinnon
Genius 4155 points

Hi,

I'm using the spreadsheet to get an idea of power consumption. Most of it make sense with the exception of the the DSP option and the ARM MM.

For the DSP there are three options - Disabled, Megamodule sleep mode and enabled. The question I have is what's the difference between having the megamodule sleep mode and the enable mode? and how does it relate to utilization?

If I have the device in megamodule sleep mode and have 20% utilization what's the difference between that and active mode and 20% utilization? In one mode does the spreadsheet assume that when not being utilized then you are in sleep mode?

For the ARM MM  there are 4 modes - is there a typical rule of thumb as to the difference between Low, Medium and high activity? - does this really relate to the OS and the amount of time is is waiting for something versus the OS firing off tasks?

Thanks

Calum

  • 0
    TI__Expert 8785 points

    Calum,

    Calum Mackinnon said:
    For the DSP there are three options - Disabled, Megamodule sleep mode and enabled. The question I have is what's the difference between having the megamodule sleep mode and the enable mode? and how does it relate to utilization?

    Below is a description of the DSP options

    • Disabled is when the DSP is PSC disabled (e.g., clock to the DSP is turned off)
    • Megamodule sleep mode is when the DSP is PSC enabled (clock to the DSP is turned on), but the DSP is in a powered down state.  More detailed description is provided in the DSP Megamodule user guide (http://focus.ti.com/lit/ug/sprufk5a/sprufk5a.pdf) in section 9.2.5 C674x Megamodule Power-Down.  
    • Enabled is when the DSP is PSC enabled with everything powered on.  Utilization is used to describe the amount of time the DSP is doing something useful.
      • 0% means the DSP is in IDLE mode
      • 100% means the DSP is executing an instruction every cycle on every functional unit

     

    Calum Mackinnon said:
    For the ARM MM  there are 4 modes - is there a typical rule of thumb as to the difference between Low, Medium and high activity? - does this really relate to the OS and the amount of time is is waiting for something versus the OS firing off tasks?

    Below is a description of the ARM options

    • Low activity is when the ARM is executing code with cache disabled
    • Typical activity is when the ARM is executing code with cache enabled
    • High activity is when the ARM is running a code that requires alot of ARM processing, such as the ARM Dhrystone benchmark program

     

    Let me know if you have any additional questions.

    --Christina