Measuring Bealeboard power consumption

Hi there,

I'm working on energy-efficient systems based on ARM, so I wanted to
measure the power consumed by a Cortex-A8-based device like the
beagleboard, if possible, making charts to compare the power consumed
by the base system, with applications running, with the board on
sleep, etc.

What would be the cheapest way to measure this power consumption? Are
there cheap amperimeters that can measure power with a miliwatt
resolution, and that can provide that data via USB or Serial, so I can
plot it?

Regards,
Ismael

BB xM SRM, page 53.

j.

Note also that there are lots of possibilities to minimize the power consumption for any particular purpose. This is not trivial, though… Good luck!

siñ

The write-up says "2.5 Watts", I believe, but this must vary a lot
depending on attached peripherals, CPU activity, etc. Some of the ICs
on the board run rather hot to the touch, more than I'd have expected
for 2.5W.

Google is your friend: "usb digital ammeter". Actually, this would
be a nice application for the BB itself. Use the ADC channels to
measure its own current draw. (Easy to say, harder to do!) Has anyone
done this?

Martin

The write-up says "2.5 Watts", I believe, but this must vary a lot
depending on attached peripherals, CPU activity, etc. Some of the ICs
on the board run rather hot to the touch, more than I'd have expected
for 2.5W.

That's exactly the point: I want to play with several hardware and
software configurations, until I find the optimal balance of features/
power drain for our purposes.

Google is your friend: "usb digital ammeter".

Thanks a lot, I really didn't know what to google for, but that was
exactly what I needed. The cheapest of the devices I could find
previously was 300€

Actually, this would
be a nice application for the BB itself. Use the ADC channels to
measure its own current draw. (Easy to say, harder to do!) Has anyone
done this?

According to Jacek Radzikowski's reference, it's possible. However,
I'd rather use an external measurement tool: I don't think it's a good
idea to manipulate any object to measure the object itself, specially
if I want to measure the power consumption when the board is asleep,
booting up, etc.

I've just noticed that this email ended up in drafts folder, instead
of being sent to the list.

According to Jacek Radzikowski's reference, it's possible. However,
I'd rather use an external measurement tool: I don't think it's a good
idea to manipulate any object to measure the object itself, specially
if I want to measure the power consumption when the board is asleep,
booting up, etc.

You can always connect an external meter to the test points to measure
the voltage drops across the resistor, or remove the resistor and
connect current meter in place of it.
A simple differential amplifier and a microcontroller with ADC and
serial port should be sufficient to record current consumption for
various types of loads.

j.

The problem is that if you use SW you are measuring the power consumption of the measuring SW. And, there is a way to do this. You can read section 6.4 of the System Reference Manual. http://circuitco.com/support/index.php?title=BeagleBone

Best way is to connect a GOOD meter in series with the DC input to the board.

Gerald

If the BeagleBoard is the -xM or the original one, you can find the SRM here.

http://circuitco.com/support/index.php?title=Main_Page

Gerald