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AM335x Deep Sleep power consumption of Beaglebone Black

Ajay Kar
Prodigy 80 points

Hello,


We are working on Beaglebone Black board. We will be using this as main processing unit as it is, on our custom board as final product.

As our product will be working on Battery. So, target is the main processing unit (whole beagle board) should consume around 10 to 12 mA with 5 V supply.

Where as when I put board into low power (deep sleep) using command

# echo mem > /sys/power/state

It works fine and wakes up good. But it consumes 50mA in deep sleep state. Where our target is 12mA. I am measuring current at 5V DC jack.

Presently I am using ti-sdk-am335x-evm-07.00.00.00.

I checked the linux source for making DDR into self refresh mode. But arch/arm/mach-omap2/sleep33xx.c do not have code for putting DDR into self refresh mode.  Thats where I am suspecting the major power consumption is going. And I am not sure about how much PMIC would be consuming.

DO we have any exiting Linux kernel source base where, it put all peripheral into power down mode. All peripheral include DDR3, emmc, SDCARD, LAN.

Thanks and Regards

Ajay Kar

 

  • 0
    TI__Guru**** 393215 points

    Hi Ajay,

    See this wiki for AM335X power consumption: http://processors.wiki.ti.com/index.php/AM335x_Power_Consumption_Summary

    DDR3 cannot be powered down in DeepSleep0 mode. It is put in self-refresh though.

  • 0 in reply to Biser Gatchev-XID
    Prodigy 80 points

    Thanks Biser,

    I have gone through the link you provided. But it talks about processor power consumption and not about peripherals power consumption.

    My requirement is over all board power consumption. I am suspecting the kernel image I got from TI sdk 7.0 donot put DDR into self refresh mode. I have concluded this by looking into kernel source. 

    Path : arch/arm/mach-omap2/sleep33xx.c

    AS you said, it put DDR into self refresh mode. if that is the case. Board should not consume 50mA of current.  As, I can see LAN is going into power down as LED goes off.And I have manually configured HDMI chipset into lowpower using i2c commands. In my setup I have not connected any monitor to the board.

    May be the linux kernel source which I have, do not support it. Can you please help me pointing to git repository which support power down of all peripherals.

    Thanks and Regards

    Ajay Kar

  • 0 in reply to Biser Gatchev-XID
    Prodigy 80 points

    I am sorry, but I am using same SDK. Where I dont see code for DDR self refresh.

  • 0 in reply to Ajay Kar
    TI__Genius 15510 points

    In sleep33xx.S

            /* Put SDRAM in self-refresh */
            ldr     r1, [r0, #EMIF_POWER_MANAGEMENT_CONTROL]
            bic     r1, r1, #EMIF_POWER_MGMT_SR_TIMER_MASK
            orr     r1, r1, #EMIF_POWER_MGMT_WAIT_SELF_REFRESH_8192_CYCLES
            str     r1, [r0, #EMIF_POWER_MANAGEMENT_CONTROL]
            str     r1, [r0, #EMIF_POWER_MANAGEMENT_CTRL_SHDW]

            ldr     r1, [r0, #EMIF_POWER_MANAGEMENT_CONTROL]
            bic     r1, r1, #EMIF_POWER_MGMT_SELF_REFRESH_MODE_MASK
            orr     r1, r1, #EMIF_POWER_MGMT_SELF_REFRESH_MODE
            str     r1, [r0, #EMIF_POWER_MANAGEMENT_CONTROL]

            ldr     r1, dram_sync_word      @ a dummy access to DDR as per spec
            ldr     r2, [r1, #0]

    Steve K.

  • 0 in reply to Steve Kipisz
    Prodigy 80 points

    Thanks Steve

    I saw this code. But believed this code makes "on chip 64KB SDRAM" into self refresh mode, but not DDR3. I will look in the code again and get back.

    Thanks and Regards

    Ajay Kar

  • 0 in reply to Ajay Kar
    Prodigy 80 points

    Thanks Steve,

     

    I went through the code base.  If I check theoretical quiescent current analysis of all components then we should be able to achieve around 15mA. So, I am not sure where remaining 35mA is getting consumed.

    As, of now I donot have any way to check which component is consuming how much current in low power. Can you please suggest any way I can check individual component current consumption.

    And even I am not sure about how much PMIC would be consuming. I mean what PMIC would be consuming. As it remain active when we put cpu into deep sleep mode.

     

    Do you have any power analysis report on beagle bone black for complete, not only for processor?

     

    Do, you think that 12 to 15 mA with 5V supply will be possible to achieve.

  • 0 in reply to Ajay Kar
    Prodigy 80 points

    Thanks a lot your help. 

    I figured it out, where the extra power is getting consumed. On Beaglebone Black, HDMI and LAN remain active even though we put system in deep sleep mode. 

    After removing power to HDMI and LAN, The total current board use is 18mA with 5V. So, total standby power we can achieve on Beaglebone Black board is around 0.1W

    HDMI alone consume 21mA. LAN consumes 11mA.

    Just thought of sharing it. Can be useful for some body.

    Thanks and Regards

    Ajay Kar

  • 0 in reply to Ajay Kar
    Prodigy 10 points

    Hi Ajay Kar

    we are also working with a BBB for a scientific research program. We also would like to use the low power states of the BBB for battery driven applications. We are using latest Debian image (Linux version 3.8.13-bone67, Debian 7.6 wheezy).

    Problem is, we are quite new to linux, so the question is, if it would be possible to use the mentioned Debian system to use the low power features?!

    Maybe you can give some hints where to start?!

    Thanks in advance

    Christian

  • 0 in reply to Ajay Kar
    Prodigy 10 points
    Hello, How did you manage to disable LAN and HDMI Power? Using Software or did you modify the Hardware? Thank You, Regards, Christian
  • 0 in reply to Christian Artner
    Prodigy 10 points
    FWIW, the datasheet for the TDA19988 HDMI transmitter (gives a typical power consumption in "Standby Mode" (everything turned off, just listening on i2c) of 0.018 mW.

    The LAN chip (SMSC LAN8710A) gives a minimum consumption of 2.4 mW (excluding "power applied to the magnetics") in "General Power Down" mode.