igel1974
Posts: 8
Joined: Thu Oct 31, 2013 6:22 pm

Lowest power usage

Thu Oct 31, 2013 6:43 pm

Hello,

i think about to build a autonomous robot and search for an easy, cheap and low power controller. I read something about 3,5 watt, but it can be decreased by underclocking.

How much can the power usage dropped? What if i need no gpu, usb, sound, lan? I guess i only need gpio/csi.
Possible to turn all other off to save power?

I see at amazon (i am from germany) that there are 2 raspberry offers, looks both Rev. B but with different prices!?
Where is the diff. of these both?

http://www.amazon.de/Raspberry-Pi-RBCA0 ... =raspberry
http://www.amazon.de/Raspberry-Mod-Rev- ... =raspberry

greetz

ShiftPlusOne
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 6229
Joined: Fri Jul 29, 2011 5:36 pm
Location: The unfashionable end of the western spiral arm of the Galaxy

Re: Lowest power usage

Thu Oct 31, 2013 6:51 pm

If you don't need USB, you can cut about a third off the power usage with this trick:

Code: Select all

echo 0x0 | sudo tee /sys/devices/platform/bcm2708_usb/buspower
(Don't run this unless you know what you're doing)

igel1974
Posts: 8
Joined: Thu Oct 31, 2013 6:22 pm

Re: Lowest power usage

Thu Oct 31, 2013 7:03 pm

ShiftPlusOne wrote:If you don't need USB, you can cut about a third off the power usage with this trick:

Code: Select all

echo 0x0 | sudo tee /sys/devices/platform/bcm2708_usb/buspower
(Don't run this unless you know what you're doing)
Wow, USB take 1/3 off the power even nothing is connected!
So i can drop to ~2,3 watt just turn usb off. Thx for the info.

igel1974
Posts: 8
Joined: Thu Oct 31, 2013 6:22 pm

Re: Lowest power usage

Thu Oct 31, 2013 8:03 pm

I found that nice info: http://www.daveakerman.com/?page_id=1294
and decide to buy a Rev. A. that uses 1/3 of the power Rev. B takes.

I guess i can live with half of the memory.

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 26716
Joined: Sat Jul 30, 2011 7:41 pm

Re: Lowest power usage

Thu Oct 31, 2013 8:06 pm

igel1974 wrote:
ShiftPlusOne wrote:If you don't need USB, you can cut about a third off the power usage with this trick:

Code: Select all

echo 0x0 | sudo tee /sys/devices/platform/bcm2708_usb/buspower
(Don't run this unless you know what you're doing)
Wow, USB take 1/3 off the power even nothing is connected!
So i can drop to ~2,3 watt just turn usb off. Thx for the info.
Yes, the chip on the B that provides the ethernet and USB hubs is quite thirsty.
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