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Power management on Beagleboard xM

Other Parts Discussed in Thread: TFP410, DM3730

Hello,

 

I'm working on the BeagleBoard xM board (http://beagleboard.org/hardware/design),

and i'm trying to minimize the power consumption on Idle Mode.

 

I use the Linux from

AM35x-OMAP35x-PSP-SDK-03.00.01.06

AM35x-OMAP35x-LINUX-PSP-04.02.00.07

 

 

Before coming in Idle mode, set the GPIO output to reduce power consumption :

 

GPIO210 = 0

   turn OFF the external USB Hub (USBHOST_PWR_EN)

 

GPIO147 = 0

   turn OFF the 3 ports USB Hub (USB2HS_nRST)

 

 GPIO211=1

   turn OFF the LEDB PMU

 

GPIO194=0

    turn OFF the TFP410

 

Enter in Idle Mode :

echo mem > /sys/power/state

 

And I've a power consumption of 200mW.

 

I attempt to turn OFF the 26MHz Oscillator which going into the DM3730.

Normally, when the DM3730 enter in Idle Mode, It set its output SYS_CLKREQ to 0, and the companion chip turn OFF the 26MHz by the signal CLKEN.

 

But the DM3730 doesn't low this SYS_CLKREQ.

I've verified the register PRM_POLCTRL which have a good configuration :

CLKOUT_POL = 0

CLKREQ_POL=1

 

Is it because of power domain or clock domain don't turn OFF ?

 

Does it exists other technique to get lower power consumption ?

 

Thanks