Switching off the ethernet module


5 posts
by Un4Seen » Mon Dec 17, 2012 2:01 pm
Hi!

I just saw a video about the new RPI model A being tested at AdaFruit, which is very intriguing. This video (which you can see here: http://www.youtube.com/watch?feature=player_embedded&v=byPQcTj1LC0) shows two RPIs, a model A and a model B being tested for power consumption. I assume that both of them are running "empty", without much CPU load or anything else, because they both consume relatively little power.
What really shocked me is that while model B is using 0.31A @ 5V (1.55W), model A is only using 0.1A @ 5V (0.5W). Yes, we all knew that model B consumes more power, but I was not expecting such a big difference, not by far...
This is very interesting news to me because I keep a model B running almost 24/7 and I'm one of those people who just don't like wasting power, not even 1W of it :) Also, I plan to run the RPI on a battery in the future, so that big difference really matters.
It seems that the big difference in power consumption is mostly (or entirely?) generated by the Ethernet module (which exists only on model B). I don't use the Ethernet module anyway, because I communicate with the Pi through a USB WiFi dongle. So the question which immediately came to mind was: is it somehow possible to switch off the Ethernet module on model B to reduce power consumption? I'm not really thinking of some extreme method, like soldering it off physically, rather a software-based approach like disabling it in the OS or disabling it with a firmware update. Is this possible somehow?

PS: I'm not sure at all that this is the right part of the forum to post this topic to, so if I have put it into the wrong place, I apologize.

Thanks,
Andras
Andras
http://iqjar.com
User avatar
Posts: 288
Joined: Wed Oct 31, 2012 8:43 am
Location: Cluj-Napoca, Romania
by RaTTuS » Mon Dec 17, 2012 2:12 pm
no - as it also provide the USB ports but even so you cannot switch it off
1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX - Prosliver FTW
"That's not right, the badgers have moved the goalposts."
User avatar
Posts: 5167
Joined: Tue Nov 29, 2011 11:12 am
Location: North West UK
by Un4Seen » Mon Dec 17, 2012 2:18 pm
RaTTuS wrote:no - as it also provide the USB ports but even so you cannot switch it off


Hmm. But then what provides the USB on model A, which does not have an Ethernet module?
Anyway, it's a shame it cannot be disabled. I'd buy a model A instead, but that only has 256MB of RAM. The golden solution for me would be a model which consumes as little power as model A but has as much memory as model B :)
Andras
http://iqjar.com
User avatar
Posts: 288
Joined: Wed Oct 31, 2012 8:43 am
Location: Cluj-Napoca, Romania
by RaTTuS » Mon Dec 17, 2012 2:20 pm
there is a USB on the SOC but it is only one channel, this is converted into 2 by the Ethernet / USB chip...
1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX - Prosliver FTW
"That's not right, the badgers have moved the goalposts."
User avatar
Posts: 5167
Joined: Tue Nov 29, 2011 11:12 am
Location: North West UK
by Un4Seen » Mon Dec 17, 2012 2:23 pm
RaTTuS wrote:there is a USB on the SOC but it is only one channel, this is converted into 2 by the Ethernet / USB chip...

I see. Well, one USB slot would be plenty for me.
Thank your for your answers!
Andras
http://iqjar.com
User avatar
Posts: 288
Joined: Wed Oct 31, 2012 8:43 am
Location: Cluj-Napoca, Romania