Sleep Raspberry Pi

Hello Everyone,
I build meteorological balloon and I want to reduce power consumption.
How can I sleep Raspberry Pi ?
Is there any way to do it.
Project will be on A+.
Thanks
Reply to
Janek Jaracz
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Only relevant article I can find focusses on using a switching regulator instead of Pi's inbuilt linear regulator,
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I am guessing that the peripheral chips draw power irrespective of usage.
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Reply to
The Natural Philosopher
The A+ (and the B+) both have switching regulators to take the 5v to 3.3 and 1.8v.
Other than there, there really isn't much you can do - other than go through all of Dave Ackermans blogs, etc. to see how he does it. I suspect "big batteries" is the way forward.
You can't really "sleep" the Pi, however you can halt it - in a way that it can be woken by an external signal (either toggle the reset line or pull one of the I2C pins to 0v) but that's a complete re-boot...
Gordon
Reply to
Gordon Henderson
I haven't looked at the hardware manual in a while, but I would be *very* surprised if the CPU didn't have significant power down features. I know this chip is designed for set top boxes rather than cell phones, but nearly every CPU these days has power reduction features.
If not, the OP might want to consider some other products like a Beagle Bone or even a lower end device like an Arduino. I know weight is a major issue for airborne applications and I'm sure there are plenty of other choices that will do the job easily. The MSP430 is a very capable CPU and can sleep using no more power than a wrist watch.
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Rick
Reply to
rickman
Sure, but Linux already uses them. Apparently he wants to save even more power. Indeed that can be done using "halt".
Reply to
Rob
Does the CPU have a built in timer to wake the processor back up?
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Rick
Reply to
rickman
No idea... but I think the CPU sleeps any time there is no process ready to run. It will wake up when an interrupt arrives.
Reply to
Rob
Equally to the point, what does the OP want the RPi to do and/or control?
We don't know anything about that. If its something fairly simple, maybe a single chip solution like one of the PICAXEs could handle it. That would be cheaper, lighter and maybe even lower powered than using an RPi. OTOH, if he's planning to carry something that doesn't like really cold temperatures, e.g. some types of camera, he may find that using a well- insulated box and bigger batteries is the way to go because keeping the RPi running contributes to keeping the payload warm.
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martin@   | Martin Gregorie 
gregorie. | Essex, UK 
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Reply to
Martin Gregorie
I want to sleep or halt RPI after operation or if currently do nothing. For example, if camera take a photo then RPI save picture and information fro m sensors to log and go to sleep or halt.
W dniu pi?tek, 19 grudnia 2014 15:18:58 UTC+1 u?ytkownik Martin G regorie napisa?:
Reply to
Janek Jaracz
So I'm certainly not an electronics expert but what about using a flip-flop timer or something like that. Set it, halt the Pi, the first flop turns off the power, a capacitor discharges, another flop and at that point it turns back on?
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Knute Johnson
Reply to
Knute Johnson
Have you measured power consumption to know whether the effort of stopping it is worth it?
FWIW, here are the numbers for my series 2 model B, which I run headless, so the only active 'periperals' are the wired ethernet interface and the SD-card, an 8GB micro-USB card in an adapter. The power consumption was measured with a standard Maplins wattmeter fitted between the mains socket and the USB power supply. I have a switch fitted in the USB power cable. Here are the numbers I read off the wattmeter.
1) RPi booting up: 2.8 - 3.0 w 2) RPi booted, logged in over SSH, sitting idle: 2.4 - 2.5 w 3) as (2) but compiling a C program: 2.7 - 2.8 w 4) RPi halted. Only red LED on: 0.6 w 5) power switch in USB cable OFF: 0.0 w
IOW the USB PSU doesn't use any power when there's no load on it but I have no idea of its efficiency under load.
The RPi seems to use about 1.9w with the SSH session active but no user programs running and about 2.2w while the C compiler is running.
I have no way of knowing how much power the ethernet interface uses.
I'd guesstimate 0.1w per lit LED since they are quite bright, so an active model B could easily be using 400 - 500 mW just flashing its lights at you.
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martin@   | Martin Gregorie 
gregorie. | Essex, UK 
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Reply to
Martin Gregorie
What will actually trigger an 'activity'? Is it just one thing or one of many?
How frequently will the Pi need to wake up and (roughly) how long for?
How long can the triggering source hold on to it's data before the Pi *must* be able to accept it?
Depending on the number/type of peripherals and relative power consumption, it may be better to keep the Pi running all the time and use it to switch the peripherals on and off.
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W J G
Reply to
Folderol
Disable it and compare, see
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(disables the complete usb hub, though).
Reply to
A. Dumas
Only way to wake it from halt is a hard reset, leading to a full reboot. So, no.
Reply to
A. Dumas
I have not measured it, but the difference is less than I expected to see. On an Intel PC the difference is much, much more.
Reply to
Rob
No. However this can be implemented with a gertduino board (and possibly others, but thats one I have 1st hand experience of, as I wrote some code for it)
You can tell the RTC CPU on the Gertduino what time you want woken up then execute a halt/shutdown, then at the appropriate time the Pi will be rebooted.
I'd fit bigger batteries.
Gordon
Reply to
Gordon Henderson
The OP is using a model A+ which doesn't have an Ethernet interface or USB hub.
Gordon
Reply to
Gordon Henderson
A. Because it spoils the flow.
Q. Why is top posting considered bad?
Reply to
mm0fmf
My RPi is only ever run headless, which makes that a little difficult. Not that I care about my Pi's power consumption particularly: its certainly low enough for anything I'll use it for.
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martin@   | Martin Gregorie 
gregorie. | Essex, UK 
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Reply to
Martin Gregorie
Yes, I know that, thanks.
I don't have any version an RPi A so I measured what I've got and posted that as a, hopefully, useful set of numbers.
I mentioned the network port and USB PSU efficiency as power losses the OP won't have and muttered about the LEDs as something he can disable, disconnect or rip out to save somewhere around 25-30% of his RPi's power consumption.
As mine showed a higher power requirement while booting than when it was doing some moderately intensive computation, you can also conclude that booting it, doing whatever needs doing and then shutting it down until the next active point might use more power than leaving it running. Unless, that is, its active period is a lot shorter than the duty cycle.
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martin@   | Martin Gregorie 
gregorie. | Essex, UK 
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Reply to
Martin Gregorie

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