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Application Wattage
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Application Wattage

by pavan168 on Mon Aug 16, 2010 2:29 am

Hi,

I'm planning to do a project. One of the things i want is to measure the ampere's into an application. so 1st i need to build an application and for that i need that ampere value from the ammeter ive plugged into the computer application. say, ive plugged the ammeter into the power that takes to the motherboard. so i want the ampere reading in my application.

How do i get these kinda values into my application? Ive no clue but i want to learn the coding and all..

Thanks :)
Last edited by pavan168 on Thu Aug 19, 2010 2:37 am, edited 1 time in total.
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Re: Measuring values in an app from a elec. device

by adafruit_support_bill on Mon Aug 16, 2010 6:08 am

The coding will depend on what device you are using to measure the current. Does your ammeter have a computer interface?

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Re: Measuring values in an app from a elec. device

by pavan168 on Mon Aug 16, 2010 6:19 am

Most probably i will be using few ammeters but it has no connection with the computer. Just the wires are connected and its not USB or anything. So how can i get the input?

Is there a way?
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Re: Measuring values in an app from a elec. device

by adafruit_support_bill on Mon Aug 16, 2010 6:47 am

There are digital ammeters with serial interfaces, but they are fairly expensive: http://www.laurels.com/dcmeter.htm

Have you looked at the Tweet-A-Watt project? http://www.ladyada.net/make/tweetawatt/
That does wireless power monitoring. One person on the forum has modified this to work over an RS-232 interface as well.

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Re: Measuring values in an app from a elec. device

by pavan168 on Mon Aug 16, 2010 6:58 am

I'll check more about the digital ammeter.

Can i measure the power consumption of the CPU with Kill-A-Watt?

+ ive to specifically measure it to a single process (e.g. firefox) and im assuming that there's no way of measuring without having to do it physically?
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Re: Measuring values in an app from a elec. device

by adafruit_support_bill on Mon Aug 16, 2010 7:26 am

Can i measure the power consumption of the CPU with Kill-A-Watt?


Do you mean only the CPU chip? Or the whole computer (power supply, disk drives, memory etc.). A Kill-A-Watt can measure the power consumption of your computer, but you would need some specialized instrumentation to isolate the power utilization of the CPU chip alone.

ive to specifically measure it to a single process (e.g. firefox)


An ammeter/wattmeter alone is not going to be able determine what power went to individual processes. You will need to measure the power consumption of the whole computer, then use the operating system process statistics to figure out what percentage of the CPU time was used by firefox. This would be an approximation, as there are other CPU-specific variables such as power-saving modes during idle time etc.

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Re: Measuring values in an app from a elec. device

by pavan168 on Mon Aug 16, 2010 7:42 am

Do you mean only the CPU chip? Or the whole computer (power supply, disk drives, memory etc.). A Kill-A-Watt can measure the power consumption of your computer, but you would need some specialized instrumentation to isolate the power utilization of the CPU chip alone.


Only the CPU chip. So would like to know if there is a special instrument to measure only the CPU itself or if i have to use the Kill-A-Watt, what instruments to use to isolate the power utilization of the CPU chip alone?

An ammeter/wattmeter alone is not going to be able determine what power went to individual processes. You will need to measure the power consumption of the whole computer, then use the operating system process statistics to figure out what percentage of the CPU time was used by firefox. This would be an approximation, as there are other CPU-specific variables such as power-saving modes during idle time etc.


Total Watt for CPU x CPU usage for that particular process (percentage) would give an approximate answer, am i right?
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Re: Measuring values in an app from a elec. device

by adafruit_support_bill on Mon Aug 16, 2010 8:14 am

The Kill-A-Watt is not going to help you measure the power consumption of the CPU chip. It is only good for measuring 120V AC power. Your CPU will be running on a much lower DC voltage.

To measure power consumption of the CPU chip, you would need to have physical access to the power pin on the chip itself, and a sensor probe small enough to attach to it. At the very least this means removing the motherboard from your computer. A test-station like this would probably do the job: http://www.teradyne.com/ict/teststation-in-circuit-test/12x.html. Lower cost options would probably involve removing the CPU chip and inserting some kind of adapter to give you access to the pins. Others with more experience in this area may have more suggestions.

Total Watt for CPU x CPU usage for that particular process (percentage) would give an approximate answer, am i right?

Yes.

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Re: Measuring values in an app from a elec. device

by pavan168 on Tue Aug 17, 2010 12:45 am

Guys is there anyway i could measure the power consumption for a particular application without having to do it physically? (like keep it at Idle then when the program is running to test it using a watt meter).

If there is no chance of doing that way, say we have to measure it physically for each application. but cant we have a way of measuring without having to do it individually for each application?
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Re: Measuring values in an app from a elec. device

by franklin97355 on Tue Aug 17, 2010 7:32 pm

Your question is not clear to me. Can you explain exactly what it is you want to measure and how you plan to connect to the part you are testing. There are ways to do just about anything if you are willing to pay for the equipment and time. It sounds like what you want won't be cheap.

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Re: Measuring values in an app from a elec. device

by pavan168 on Wed Aug 18, 2010 4:56 am

Main thin i want to do it is to calculate the power consumption to specific application. It can be any program. (e.g for firefox, Maya) like wise....
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Re: Measuring values in an app from a elec. device

by adafruit_support_bill on Wed Aug 18, 2010 8:56 am

It would be a lot easier if you were to measure the total system power consumption of your PC, or even just the motherboard. It would also be a more meaningful result. Applications such as Firefox consume more than just CPU cycles, they render graphics, communicate over the ethernet interface and write files to disk. All of those things consume power.

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Re: Measuring values in an app from a elec. device

by pavan168 on Thu Aug 19, 2010 2:09 am

when it comes to a task you cant think of the easy way out and specially calculating total PC power consumption is not the requirement. Anyone can do that dude! But this is major. Thanks for your help though.

I'm still figuring out a way?
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Re: Application Wattage

by richms on Thu Aug 19, 2010 5:43 am

If you can find a way to do it, then you will make millions by making it so people can invoice for the use of their CPU.

IMO, it cant be done.

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Re: Application Wattage

by franklin97355 on Thu Aug 19, 2010 10:58 am

IMO, it cant be done.

Sure it can. all you need to do is build a board that goes between the cpu socket and the cpu so you can pull all the power pins out and measure them. If you have enough time and money (almost) anything is possible.

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