vk3pb
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Request for ultra low power pi

Sat Nov 23, 2013 11:37 am

Hi all

I'd like to make a request for an ultra low power pi at some point in the future.

Yes I know that the model A can be run below 1 watt but I want a reduction in power by a magnitude or more.

Why? Think about the crystal sets you used to make when you were a kid. They were able to tune a local AM radio signal and provide enough power to drive a crystal earphone. If the power consumption of a pi could be reduced to these levels then a pi could be run off a simple coil and capacitor and a few diodes. There would be no need for a solar cell.

Also such a low power pi would enable users to develop applications where the pi would run off batteries fro months or even years. This would considerably expand the uses that the Pi could be put to.

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joan
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Re: Request for ultra low power pi

Sat Nov 23, 2013 11:41 am

Quite agree. I want a Pi which uses microwatts. That would last for centuries with a single AAA cell.

MoosePi
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Re: Request for ultra low power pi

Sat Nov 23, 2013 11:43 am

When will there be a NEW Raspberry Pi?

http://www.raspberrypi.org/phpBB3/viewt ... 63&t=56598
Pi Forum Search and Google yields answers to many questions

DominusPi
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Re: Request for ultra low power pi

Sat Nov 23, 2013 11:59 am

I believe if you underclock it and make it stop checking for USB, Ethernet .. (Or whatever you don't need) signals, you will already considerably reduce the consumption.

I'm absolutely no expert, just rational thoughts here :roll:
Cheers !

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mahjongg
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Re: Request for ultra low power pi

Sat Nov 23, 2013 12:51 pm

perhaps I want a horse that "runs" on one sugar cube for a year!
advances in biological science should make that possible for sure :!: :mrgreen: :roll:

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mahjongg
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Re: Request for ultra low power pi

Sat Nov 23, 2013 12:59 pm

DominusPi wrote:I believe if you underclock it and make it stop checking for USB, Ethernet .. (Or whatever you don't need) signals, you will already considerably reduce the consumption.
the model A already doesn't have an Ethernet Chip, and "stop checking" for USB won't make the USB hardware magically disappear, so even "in rest" it will still use about the same energy. An Active USB port will use energy, but most of it will go in sending signals to another USB device, without such a device attached no energy is used by trying to send those signals. So almost no power is saved by turning the USB stack off if already no USB devices are connected. Not that there are many other, better ways, to save some energy. Even when you use them all they won't lead to "a reduction in power by a magnitude or more." that is they won't allow the PI to run on a tenth of the current power.
Perhaps though you can reduce the power consumption with 10% or so using all the tricks that are imaginable, like underclocking.

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DexOS
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Re: Request for ultra low power pi

Sat Nov 23, 2013 1:06 pm

This is where i think a bare metal OS, has a big advantage over OS like linux.
It would make a great compo in the bare metal part of the forum.
The winner would be the one that got a Model A to last the longest on a set of batteries and flash a led etc. :idea:
Batteries not included, Some assembly required.

totoharibo
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Re: Request for ultra low power pi

Sat Nov 23, 2013 1:30 pm

arduino ?

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aTao
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Re: Request for ultra low power pi

Sat Nov 23, 2013 1:35 pm

If you want minimal power, you dont want an OS, If you havent got an OS you dont need a computer, a microcontroller should do the job. All said, pick a different system.

Or run it from PV panels. In that case if you can see it, it will run.
>)))'><'(((<

Heater
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Re: Request for ultra low power pi

Sat Nov 23, 2013 1:42 pm

Try an Espruino board.

Some of the lowest power consumption but useful computers today are single chip micro-controllers like the STM32 series. Down to about a hundred micro-amps when resting, ready to respond to any input change. Will run on a battery for weeks or months.

These MCU are often complex to program but now you can write useful applications for them in JavaScript. No operating system just a very small JS interpreter, very easy to use. The Espruino board is designed around these principals. Offering 48 I/O pins and UART, SPI etc.

Check out Espruino here:
http://www.espruino.com/

The Espruino software is open source and easy to build for many other STM32 boards from a variety of manufacturers.
Memory in C++ is a leaky abstraction .

hippy
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Re: Request for ultra low power pi

Sat Nov 23, 2013 2:29 pm

vk3pb wrote:I'd like to make a request for an ultra low power pi at some point in the future.
If the technology ever exists I am sure you will get it.

I would like an engine which can deliver 200kph, pull a 40-tonne trailer, and do so consuming a thimble of fuel a year. Such an engine doesn't exist. I can have the speed and pulling power if I accept higher consumption or I can have lower consumption without the speed or pulling power. Those are the choices today.

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redhawk
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Re: Request for ultra low power pi

Sat Nov 23, 2013 3:22 pm

Why? Think about the crystal sets you used to make when you were a kid. They were able to tune a local AM radio signal and provide enough power to drive a crystal earphone. If the power consumption of a pi could be reduced to these levels then a pi could be run off a simple coil and capacitor and a few diodes. There would be no need for a solar cell.
This is a baseless argument you might as well use a abacus instead of a calculator because it doesn't require batteries.
The Pi's power requirement for the Model A is pretty low as it is but the SD card and the SoC must have 3.3v to function correctly and 5v is required to power USB devices.
I believe you could probably improve power efficiency by replacing the 3.3v linear regulator with a switch mode as long as there is sufficient noise filtering.

Richard S.

Heater
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Re: Request for ultra low power pi

Sat Nov 23, 2013 4:26 pm

Odd how one can build a crystal set and not learn anything from it.
Memory in C++ is a leaky abstraction .

MoosePi
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Re: Request for ultra low power pi

Sat Nov 23, 2013 6:47 pm

...could I power this new super duper Pi from a Potato ? http://www.crystalradio.net/contest/paul2.html
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mahjongg
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Re: Request for ultra low power pi

Sat Nov 23, 2013 10:15 pm

MoosePi wrote:...could I power this new super duper Pi from a Potato ? http://www.crystalradio.net/contest/paul2.html
there are some microcontrollers today you could power from a "potato battery", like this one http://www.futurlec.com/News/Microchip/nanoWatt.shtml
In fact the swiss managed to design a "computer chip" many decades ago, to put inside a watch, and run it from a button battery. off course such a chip doesn't create HDMI video! In fact the HDMI connection signals alone would use a hundred times more energy than this chip!

vk3pb
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Re: Request for ultra low power pi

Sun Nov 24, 2013 2:18 am

by aTao » Sat Nov 23, 2013 11:35 pm
"If you want minimal power, you dont want an OS, If you havent got an OS you dont need a computer, a microcontroller should do the job. All said, pick a different system.

Or run it from PV panels. In that case if you can see it, it will run."

You don;t always have access or room for solar panels for all applications. As for microcontrollers they could not handle sophisticated tasks like decoding digital radio transmissions.

I want/need low power consumption and the power of a computer so that my applications can run for years but do very sophisticated things.

cheers Peter

Heater
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Re: Request for ultra low power pi

Sun Nov 24, 2013 2:32 am

vkp3b,
I want/need low power consumption and the power of a computer so that my applications can run for years but do very sophisticated things.
I get the impression that the computer builders of the world have been working on these performance/power/size issues since Babbage. They have done amazingly well so far.

Perhaps if you told us more about what you want to do we could find some alternative solutions.
Memory in C++ is a leaky abstraction .

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Re: Request for ultra low power pi

Sun Nov 24, 2013 9:04 am

vk3pb wrote:by aTao » Sat Nov 23, 2013 11:35 pm
"If you want minimal power, you dont want an OS, If you havent got an OS you dont need a computer, a microcontroller should do the job. All said, pick a different system.

Or run it from PV panels. In that case if you can see it, it will run."

You don;t always have access or room for solar panels for all applications. As for microcontrollers they could not handle sophisticated tasks like decoding digital radio transmissions.

I want/need low power consumption and the power of a computer so that my applications can run for years but do very sophisticated things.

cheers Peter
You are asking for something that doesn't really exist. High CPU power requires a lot of electrical power. Hence Smartphone batteries last about a day....
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merlin32768
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Re: Request for ultra low power pi

Sun Nov 24, 2013 9:42 am

This is an interesting topic - after all, who doesn't want to save our hard-earned pennies from the clutches of the evil energy companies?

On a purely practical note, the Pi is already an extremely economical computer to run, and although it's always great when you can reduce power consumption even further, the law of diminishing returns comes into play, with the result that while it may well be possible to reduce the Pi's energy consumption a tad, it will come at the cost of reduced performance and/or functionality.

What I would like to see are some creative ideas on alternative methods of powering the Pi which may be appropriate for certain applications.

First of all, the power consumption of the Pi, based purely on the recommended PSU ratings, would be around 3.75W (750mA at 5V). Personally I like to have a PSU capable of at least 1A to have a safety margin, particularly on systems that are running at a slight overclock and which have to handle complex throughput and display activities (Raspbmc etc).

At this kind of power levels, the Pi is a perfect candidate for being run from relatively small batteries (a smartphone type battery is cheap to buy these days and with the addition of a voltage regulator (a 7805 will fit the bill nicely) will happily run the Pi for a few hours. (Be careful though as these batteries need a fairly special charger for safe use - never try to charge a Li-Ion battery with a home-made charger unless you REALLY know what you're doing).

What would be really cool (perhaps for developing markets in countries where the power infrastructure is not as good as that here in the west) would be a Pi-powered laptop/netbook. A standard laptop battery would run a Pi all day and all night. Of course the display panel would use quite a bit of power, but replacing the standard CFL backlight with an LED one would go a long way to cutting this, just as it has on large-screen TVs. Incorporate a small USB hub and you'd have enough connectivity for the keyboard, touchpad, drives etc and still have a couple of free ports. There would be plenty of power in reserve to run a powered USB hub so you won't have power issues and the thing could have a solar panel incorporated into the lid for free charging.

This has to be a project worth pursuing.

Remember that even at 2A, a 5V supply is still only 10W - compare that with the average laptop these days where the PSU is rated at 19V at around 4A - equating to nearly 80W!

The Pi is a potential solution to a great many energy related computing issues and given the way it has been embraced by the maker community, I can see an amazing future for it...

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Re: Request for ultra low power pi

Sun Nov 24, 2013 9:49 am

Basically just running a single PLL is going to cost about 15mW

No it's not possible on this chip...

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vk3pb
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Re: Request for ultra low power pi

Sun Nov 24, 2013 10:37 am

Heater

The idea I have is a remote controlled boat capable of self steering itself across an ocean and also receiving and sending messages and images.

Solar panels = extra weight + size. The less power I use the smaller I can make the craft.

cheers Peter

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Re: Request for ultra low power pi

Sun Nov 24, 2013 10:49 am

The Pi (and ARM) is low power (300ma) relative to a laptop/PC, comparable to a phone but not ultra low power.

If you want truly low power usage while processing you'd be better off looking at arduino or similar which can run at < 10ma
and much less when in sleep mode

A crystal radio, which can run with no battery - gets a TINY amount of current from radio waves,
what you are missing is exactly how little power a crystal set really operates on.

I was interested in this a while back so did a few tests - tuned to a strong station with a big 20 ft antenna - 0.02ma (voltage similarly tiny)
- still 1000 times too little to run even an arduino

Solar power can give plenty in comparison !

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Burngate
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Re: Request for ultra low power pi

Sun Nov 24, 2013 12:00 pm

vk3pb wrote:The idea I have is a remote controlled boat capable of self steering itself across an ocean and also receiving and sending messages and images.
Solar panels = extra weight + size. The less power I use the smaller I can make the craft.
I'm sure you've considered these, but they're just the questions that sprang to mind when I read this.

How will the boat be powered? Some sort of motor is going to use a lot more energy than the Pi. Maybe you're thinking of wind power?

Power for the steering mechanism? Again, I would guess at higher power consumption than the Pi, though I'm willing to be proved wrong.

Receiving messages may be low power, depending on bandwidth, etc. and assuming a regular transmission schedule - listen for five minutes once a day, for instance, and otherwise keep the receiver powered down.
And assuming the transmitter can be directional and high power.

However transmitting images may be a problem.
The bigger the image, the more data, so either higher data rate or longer transmission time. Either way, more energy
Unlike a balloon, your boat will be at sea level, so after the first few miles you won't be able to see it. Assuming the ocean is going to be the Atlantic, it will be upto 800km away from land, so you'll have to increase either the tx power or the rx sensitivity. Inverse square law and all that!
So it looks like this will eat into your energy budget more than the Pi will.

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Re: Request for ultra low power pi

Sun Nov 24, 2013 1:06 pm

I had the N1VG APRS weather station with a 7 Ah lead acid battery and 6 W solar panel running for two (or three?) years continuously until it stopped last June due to thunderstrom. Now I am putting my experience from that project to a solar powered computing project. See

https://github.com/oh7bf/RaspiPwr12V/wi ... spberry-Pi

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Re: Request for ultra low power pi

Sun Nov 24, 2013 3:31 pm

Nice to hear some one talk about Crystal sets
must be some one around my age
I made my first Crystal set in 1945 when I was 14.
Bought the Cats whisker diode from Curry's
Wound a coil of Double Cotton coverd wire.
Used a pair of BBC head phones I was given.
Yes it would be nice to have a very low power Pi
But you don't get anything for nothing, The outputs
would have to feed into buffer stages to to be of any use
But we are talking about times to come, But one never knows
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