RoboSK
Posts: 3
Joined: Tue Mar 20, 2012 12:54 pm

Re: Wakeup ?

Tue Mar 20, 2012 12:59 pm

Hi, is possible Wakeup Raspberry Pi on "alarm" (date/time) as on "PC" with ACPI ?

thanks

User avatar
RaTTuS
Posts: 10406
Joined: Tue Nov 29, 2011 11:12 am
Location: North West UK

Re: Wakeup ?

Tue Mar 20, 2012 1:08 pm

possibly - however you may find that the RPi uses less power than you imagine so it can be On all the time and set to do things at various times.

YMMV

and once it is running it will be able to get a clock signal from the internet [if connected]
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX
Covfefe

User avatar
SN
Posts: 1014
Joined: Mon Feb 13, 2012 8:06 pm
Location: Romiley, UK
Contact: Website

Re: Wakeup ?

Tue Mar 20, 2012 2:11 pm

plug it into one of those light timer plugs
Steve N – binatone mk4->intellivision->zx81->spectrum->cbm64->cpc6128->520stfm->pc->raspi ?

RoboSK
Posts: 3
Joined: Tue Mar 20, 2012 12:54 pm

Re: Wakeup ?

Tue Mar 20, 2012 2:28 pm

thx but it not good solution for "DVR"

User avatar
SN
Posts: 1014
Joined: Mon Feb 13, 2012 8:06 pm
Location: Romiley, UK
Contact: Website

Re: Wakeup ?

Tue Mar 20, 2012 4:17 pm

you;d be surprised actually, a 20 programme, 7 day digital timer socket is only £10.99 at Homebase http://www.homebase.co.uk/weba.....tsid:18771



And the only reason I mention this is that I have a 'sort of equivalent' setup in my car which has a Blackvue DR400G Bullet Cam mounted in the windscreen which only runs when the car is running – so in effect its timing is entirely driven by when its got power to it 0 what it does have is an internal battery which gives it the 10 seconds it needs to power down cleanly though
Steve N – binatone mk4->intellivision->zx81->spectrum->cbm64->cpc6128->520stfm->pc->raspi ?

RoboSK
Posts: 3
Joined: Tue Mar 20, 2012 12:54 pm

Re: Wakeup ?

Wed Mar 21, 2012 3:33 pm

auto scheduler &&& - me hope for "it is possible" - but if no then it is not problem...

XAPBob
Posts: 91
Joined: Tue Jan 03, 2012 2:40 pm

Re: Wakeup ?

Wed Mar 21, 2012 4:05 pm

Given that the power usage is so low (4W at full burn) you're probably best off just stopping anything that loops through CPU (e.g. XMBC UI) and anything chewing through the CPU (1080p video playing) and lettin ghte chip power regulation do it's thing.

Then cron can start up a recording process when required.

GizmoB73
Posts: 80
Joined: Fri Jan 27, 2012 12:51 pm

Re: Wakeup ?

Wed Mar 21, 2012 4:27 pm

XAPBob said:


Given that the power usage is so low (4W at full burn) you're probably best off just stopping anything that loops through CPU (e.g. XMBC UI) and anything chewing through the CPU (1080p video playing) and lettin ghte chip power regulation do it's thing.

Then cron can start up a recording process when required.



I would agree with XAPBob, as power usage could be trimmed very low, then why not leave it running?  Without an RTC you can't really shutdown and wake up at a specific time very easily.  I have no doubt that there might be an RTC add-on by some inventive soul, but do you really need one?

Just make sure you have a UPS solution (or big capacitor...) so that it doesn't go off and stay off in the case of a blip in the mains power supply.

User avatar
Gert van Loo
Posts: 2482
Joined: Tue Aug 02, 2011 7:27 am
Contact: Website

Re: Wakeup ?

Wed Mar 21, 2012 6:07 pm

The ARM can be powered down as well as large parts of the GPU. All you have running is the GPU core processor with some minimal peripherals (e.g. timer) at a very low frequency.Your power consumption will be extreemly low. I don't think that is yet possible, but that is just a matter of time for an ARM request to 'power down' is added to the ARM command set.

dom
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 5307
Joined: Wed Aug 17, 2011 7:41 pm
Location: Cambridge

Re: Wakeup ?

Wed Mar 21, 2012 8:13 pm

Currently the ARM frequency is fixed at 700MHz (a different fixed value can be specified in config.txt).

I'd like to support the cpufreq mechanism in linux to allow different profiles (e.g. performance or power saving), and the ARM frequency will vary with processor load.

It needs some plumbing, but it can be done. There's more important things to do now, but this is on the list.

(As an aside, the GPU does this sort of thing by default).

User avatar
RaTTuS
Posts: 10406
Joined: Tue Nov 29, 2011 11:12 am
Location: North West UK

Re: Wakeup ?

Thu Mar 22, 2012 8:42 am

Awesome info dom [can you give yourself an avatar] and gert
How To ask Questions :- http://www.catb.org/esr/faqs/smart-questions.html
WARNING - some parts of this post may be erroneous YMMV

1QC43qbL5FySu2Pi51vGqKqxy3UiJgukSX
Covfefe

Bakul Shah
Posts: 320
Joined: Sun Sep 25, 2011 1:25 am

Re: Wakeup ?

Thu Mar 22, 2012 9:50 am

In the 9514 (ethernet/USB) datasheet I read 4.2mA in Suspend2 mode. But it also says 42mA for `magnetic power'! Persumably that will be drawn even in Suspend2 mode? It would be interesting to know the present minimum current draw and see how low it can be brought down with some tweaking (when I get my Pi I will measure this if no one beats me to it).

While the Pi power use is low compared to a PC, it may not be low enough in situations where a battery must last a long time. For such uses probably the thing to try is to gate power using an ATtiny (in power down mode it uses mere µAmps as only its watchdog timer runs). So every N second it wakes up, supplies power and asserts a signal to the Pi to let it know it is being woken up (as opposed to powered up for the first time). Then the battle shifts to how quickly can the Pi come up to speed! The AVR board can also do some low level sensor processing before deciding to wake up the Pi.

Return to “General discussion”