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dm355 at Deep Sleep mode drops 154 mA

magda
Prodigy 135 points

Hi All,

Our first remote camera prototype is being delayed because we are having very little power saving when switching it into Deep Sleep Mode. Once we have the first prototype ready then we will be setting up a company.

These are the current measurements at normal and deep sleep mode:

Current at Normal State: 280 mA

Current at Sleep State: 154 mA

I have followed the instructions about deep sleep mode on dm355 according to sprufb3.pdf and also the Code Composer Studio Project published by a TI engineer, Miguel Alanis at:

http://e2e.ti.com/cfs-file.ashx/__key/CommunityServer-Components-PostAttachments/00-00-20-75-77/dm355_5F00_deepsleep_5F00_final_2800_2_2900_.zip

In summary these are the steps that we have followed:

. PLL1 is in bypass mode and powered down (so 24MHz are going directly to the ARM processor)

. DDR2 is in self refresh mode.

. USP Phy is powered down

. DAC and Video are also powered down.

. All the module clocks are disable through the Power and Sleep Controller.

I would really appreciate some information about:

. Power Consumption Estimation when in Deep Sleep Mode for dm355.

. Any possible module, clock, PLL... that should also be powered down in order to get a lower power consumption.

I would really appreciate if you give me some ideas on what could be going wrong.

Thanks a million!

Magda

  • 0
    TI__Mastermind 30190 points

    1) The power consumption is system level dependant. My understanding is that the current drawn by the external I/Os might make a difference in term of power consumption.
    So a part of the power consumption will be board dependant.

    What can be confusing is that 3 different boards are mentionned in the sprufb3 document:
    a) Most of the power consumption measurement were done on an APPRO board designed for Digital Still Camera (DSC). I would guess for a DSC application very little number of IOs are used. Mostly SD card, USB, imaging sensor and LCD display.
    I unfortunately could not find details on this board.

    b) The deep sleep measurement seem to have been done on an internal board. I would guess that there were almost no I/Os interfaced on this board. So it might not be representative of a real system.
    I unfortunately could not find details on this board.

    c) The deep sleep sequence (from dm355_deepsleep_final.zip) described was tested on the DM355 EVM from Spectrum Digital:
    http://c6000.spectrumdigital.com/evmdm355/reve/
    All the Guidelines for Reducing I/O Power Consumption are refering to the EVM. This sequence seems to give the most power optimized configuration for the EVM. I do not believe that there are extra modules that could be powered down.



    2) You system:
    - In your case you are using a different board (Leopard imaging board if I understand correctly) so it would make sense to look more closely if additionnal pin settings/IO settings are required.
    It might be worth to check at the board level what are the other device drawing in term of current.

    - For the purpose of measuring power It might make sense to use none OS base code as it would be easier to access the different HW modules. May be you could use the dm355_deepsleep C example as reference and modify it for the Leopard imaging board (using CCS and a JTAG emulator). For test puprose this would help to have more granularity on what you can power on/off.

    On the other side you need to have a realistic system level test scenario so at some point the complete SW stack need to be used too.


    3) It seems that Ridgerun has worked a lot with Leopard imaging HW.
    May be they implemented some deep sleep features as part of the their former DM355 Linux SDK:
    https://www.ridgerun.com/developer/wiki/index.php/Main_Page

    Hope it helps.

    Anthony