Power consumption - BeagleBoard

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1

Hi,

I have a B7 Beagleboard and I measured the power consumption to be around 300 mA (at 5V).
I am running Angstrom and have a self-powered hub connected (the hub power is not considered here).

I want to reduce the power consumption, I do not mind running the board at a slightly lower frequency. Say 350-400MHz.
I do not mind making the processor to go to sleep for a while (say for 1 minute) and then wake up again for a while (say for 10-15 seconds) and go back to sleep.

So, here are my Qs:

  1. Is it possible to run the board at 350-400 MHz? I am assuming that, this will reduce the power consumption.
  2. Is is possible to go to sleep and wake up again?
  3. What areas of the software this should be done in (or already done in)? kernel, drivers, etc.?

Thanks,
-Deven

2

Yes, this is possible - you should look into the CPUFreq interface
supported in the kernel; this supports DVFS (Dynamic Voltage Freq.
Scaling), which allows for throttling down the clock freq. of the CPU
by scaling processor voltage appropriately.

It also supports SmartReflex, which auto-adjusts frequency/voltage
operating point to match device geometry and process variations for
optimimum performance.

Finally, it supports deep sleep as well, and gating of un-used modules
power/clocks.

See this site: http://elinux.org/OMAP_Power_Management

Notice that there is a separate linux-omap-pm branch that contains
more support for power management techniques that the standard linux-
omap tree. I've run the pm branch on the my OMAP3EVM successfully, and
reported some significant savings.

Jerry
Nuvation Research Corporation

3

Yes, this is possible - you should look into the CPUFreq interface
supported in the kernel; this supports DVFS (Dynamic Voltage Freq.
Scaling), which allows for throttling down the clock freq. of the CPU
by scaling processor voltage appropriately.

It also supports SmartReflex, which auto-adjusts frequency/voltage
operating point to match device geometry and process variations for
optimimum performance.

Finally, it supports deep sleep as well, and gating of un-used modules
power/clocks.

See this site: http://elinux.org/OMAP_Power_Management

Thanks!
Now, lot of reading.

Notice that there is a separate linux-omap-pm branch that contains
more support for power management techniques that the standard linux-
omap tree. I’ve run the pm branch on the my OMAP3EVM successfully, and
reported some significant savings.

You have some numbers for power consumption. Vague numbers are also good for me.

-Deven