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Lowest Power Mode "Sleep" on the DM6446

D^2
Prodigy 40 points

Does anyone know what the lowest power mode "sleep" on the DM6446 power draw is?

I have a requirement to put the DM6446 into the lowest power mode "sleep" possible (running on battery power) and then wake on interrupt or at a scheduled time and be able to start capturing h.264 images within 1 second...

We are currently using WinCE but we are in the process of switching over to Linux.

D^2 

 

  • 0
    TI__Mastermind 37340 points

    Have you seen http://focus.ti.com/dsp/docs/dspsupporttechdocsc.tsp?sectionId=3&tabId=409&familyId=1302&abstractName=spraad6a

    I believe what you are after is the standby power which is estimated at ~330 mw. 

  • 0 in reply to Juan Gonzales
    Prodigy 40 points

    Hi Juan,

    The document and the Excel spreadsheet are excellent resources with regards to the minimum power usage of the DM6446 in "Standby" mode. Thanks for pointing me in this direction!

    As a follow-up, do you know of any information with regards to how quickly the system could be woken up from the standby mode (with an interrupt on the ARM - which is what the Standy mode seems to be waiting for) and start encoding video?

    D^2

  • 0 in reply to D^2
    TI__Mastermind 37340 points

    One second sounds like a reasonable amount of time; unfortunately, I do not have any numbers I can share.  What I can say is that I have seen presentation that claim cold boot up times of 800 msec are reachable;  I also think the time it takes to come out of reset will be highly depedent on your overall system.  For example if your file-system resides in an ATA hard drive, it may take significant amount of time for the mechanical parts of the hard drive to power back up and fetch necessary data that needs to be placed in DDR2 to start encoding h.264  Having the file system in a solid state device may be faster...Also, please note that the Linux drivers at the moment do not support power management features such as going in and out of standby, hence you will need to add this support yourself.

  • 0 in reply to Juan Gonzales
    Prodigy 40 points

    Juan,

    Thanks for the follow-up. Glad to hear that is seems at least feasible that we can put the DM6446 into standby mode and draw only 330 mW and then be able to come out of this mode and start our h.246 encoding within a second. In your work at TI do happen to know of anyone who has done any work on controlling power modes on the DM6446, either a TI person, independent person or a 3rd party supporter? I'm thinking someone has probably been down this road before and I'd sure like to find out the lessons learned to get us a working solution quicker. Do you expect MV Linux may support this better then other solutions?

    Thanks,

    D^2

     

  • 0 in reply to D^2
    TI__Mastermind 37340 points

    We have had this request come up a handful of times, but since there is no support in our Linux drivers for this, customers normally end up implementing their own solutions which we do not have access to.  In Linux, as in other operating systems, there is usually a few power management messages broadcasted to all interested parties that the system is about to go into, or get out of sleep modes.  It is up to the drivers to partake on this process and take action as a result of the broadcast.  If just one software component returns to a power management request with a failure, it typically means the entire system is kept from going into sleep.  I am not an expert on power management under Linux, but I believe the above description should hold for Linux and other OSes.