Datafreak
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Re: Wake-on-LAN (WOL)

Tue Aug 30, 2011 1:35 pm

Hi,
it is possible to wake up Raspberry Pi with a magic packet?
If not, would it possibility at the next revision?

Gruß,
Datafreak

Johannes
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Re: Wake-on-LAN (WOL)

Tue Aug 30, 2011 1:38 pm

The Raspberry Pi is either on or not connected to the power supply. When it's on, you don't need to wake it up, and when it's not powered, nothing will wake it up.

eggn1n3
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Re: Wake-on-LAN (WOL)

Tue Aug 30, 2011 1:48 pm

I guess Datafreak means if the R-Pi can be waken up from standby/hibernation mode by using wake-on-LAN. Normally this should be supported by the chipset (LAN9512). According to the specs it does (http://www.smsc.com/index.php?.....38;pid=135).

Johannes
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Re: Wake-on-LAN (WOL)

Tue Aug 30, 2011 3:31 pm

There is no standby/hibernation mode. It's either without power or it's on. There is no power switch either. You plug in the power supply and it starts. To turn it off, you unplug it.

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Lob0426
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Re: Wake-on-LAN (WOL)

Tue Aug 30, 2011 3:52 pm

Wake on LAN has to be supported by both the chipset and the OS. In a PC it also has to be supported by BIOS, but that is because it is part of the I/O chipset. The LAN9512 chipset has it's own settings. Linux does support Wake on LAN and a low power mode. I do not know if the ARM supports a low power mode but I believe it does. The chip family was designed for cell phones.
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marris2208
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Re: Wake-on-LAN (WOL)

Tue Aug 30, 2011 4:03 pm

Of course it's standby/hibernation, Linux supports it! 8O

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Lob0426
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Re: Wake-on-LAN (WOL)

Tue Aug 30, 2011 4:32 pm

Nope not what I said. It should support it. The OS supports it, the LAN chipset supports it. And I would not be surprised if a cell phone chipset supports a low power mode, not hibernation or you would not get your calls(standby). A cell phone wakes from standby for an incoming call. So I will be surprised if it cannot work. Of course since the alpha board came in at 1.35 watts I do not know why you would bother to put it to sleep at all! It was only using a little over 2 watts when running full out. The wall wart to power it will "waste" more energy than the RasPi uses. And you cannot put the wall wart to sleep!
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eggn1n3
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Re: Wake-on-LAN (WOL)

Tue Aug 30, 2011 8:42 pm

Thinking about it.... it`s also the power supply that needs to support it. With a PC with normal ATX power supply the PC is able to switch off the power (remaining just a bit of power to make it possible to switch the power back on again later). With the R-pi you only have an always on power supply that can only be switched off by removing the power connector. Johannes, this is what you mean, right?

Johannes
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Re: Wake-on-LAN (WOL)

Tue Aug 30, 2011 11:21 pm

What I mean is that there is no suspend mode. There's on and there's off. See abishur's comment here: http://www.raspberrypi.org/?pa.....038;t=2.10. With no suspend mode and no soft power off, WOL is pointless. The CPU and the GPU will use only a fraction of 1W when they're idle. Why do you want WOL? Keep the device on and use the OS for reacting to network events.

eggn1n3
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Re: Wake-on-LAN (WOL)

Wed Aug 31, 2011 7:32 am

I cannot find anything in the forums about the fact that suspend mode is not supported. Abishur's comment only refers to Liz comment about having only power on OR power off. The problem is that the power supply doesn't support a real suspend mode. It might be that the R-Pi can be in some power safe mode http://infocenter.arm.com/help.....index.html. If you are running the R-Pi on batteries anything will help to save power....

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abishur
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Re: Wake-on-LAN (WOL)

Wed Aug 31, 2011 1:23 pm

Does a cell phone support suspend mode? I can use setCPU on my android to lower the clock speed of the processor when it's not in use, but I can't put it into the standby. We'll have to take a hard look at the specs for the ARM11 (or just wait for one of the r-pi team to comment on this ;) ), but it's my guess that it doesn't support a suspend/standby mode.
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ryao
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Re: Wake-on-LAN (WOL)

Sun Sep 11, 2011 5:21 am

Quote from eggn1n3 on August 31, 2011, 08:32
I cannot find anything in the forums about the fact that suspend mode is not supported. Abishur's comment only refers to Liz comment about having only power on OR power off. The problem is that the power supply doesn't support a real suspend mode. It might be that the R-Pi can be in some power safe mode http://infocenter.arm.com/help.....index.html. If you are running the R-Pi on batteries anything will help to save power....

Wake On LAN is implemented using a microcontroller that is always on. The Raspberry Pi is also a microcontroller that is always on. Adding a microcontroller to it to get Wake On LAN functionality would just increase the power draw. Suspend is also implemented using microcontrollers and it would suffer from the same problem.

iAreNewb
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Re: Wake-on-LAN (WOL)

Sun Sep 11, 2011 5:40 am

Power supplies are described by their max power draws, I think. If the R-Pi doesn't draw the maximum, the power supply will not supply the maximum. (This is in reference to wall warts) In terms of batteries, this is also definitely true, so no extra equipment is required to implement WoL.

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