i.MX ProcessorsのトピックRe: QSB power

QSB power

TedMichon — Tue, 01 Nov 2011 22:45:23 GMT

Does anyone have experience getting the power consumption of the QSB down?

Our application does not need any of the audio or video functionality.

At the LINUX prompt the board draws 380 to 500 mA from the 5V main supply. Thats about 2W to 2.5W.

The Freescale app note says that LINUX can draw about 160 mW while playing an MP3 file from SD,

Is there some low power demo code I can run and/or does anyone have experiene reducing the power consumption of the QSB?

Thanks.

-Ted

Re: QSB power

TedMichon — Tue, 01 Nov 2011 22:55:18 GMT

Looks like there is 8 x (5.0-1.4)/470 x 5 = 306 mW just in the LEDs alone.

-Ted

Re: QSB power

PhilEndecott — Wed, 02 Nov 2011 14:41:45 GMT

What does cpufreq-info show?

Re: QSB power

TedMichon — Wed, 02 Nov 2011 23:56:48 GMT

OK, I'm new to this. What is cpureq-info?

-Ted

Re: QSB power

TedMichon — Thu, 03 Nov 2011 00:03:26 GMT

OK, I now understand that cpufreq-info is LINUX command that will provide the current frequency/power trade off info, but I'm more interested in what happens when the video and audio stuff is disabled or removed and when the power supplies are designed more efficiently than in the QSB. How close can I get the 2W that the QSB boots up to in LINUX down to the 160 mW listed in the App note for just processing MP3 video from an SD card. That's a BIG gap!

-Ted

Re: QSB power

PhilEndecott — Thu, 03 Nov 2011 10:53:12 GMT

> I'm more interested in what happens when the video and > audio stuff is disabled OK, try that then. What difference do you see?

Re: QSB power

TedMichon — Thu, 03 Nov 2011 20:46:49 GMT

If I knew how to disable these systems, then I would do so and then read the current. I'm just a hardware guy on this project.

(I was hoping someone had made some measurements and/or computations already.)

-Ted

Re: QSB power

PhilEndecott — Thu, 03 Nov 2011 22:21:43 GMT

To disable video, remove the video=mxc*** and tve stuff from the kernel command line.

Re: QSB power

PhilEndecott — Thu, 03 Nov 2011 22:22:48 GMT

(If your system is using a TV mode, rather than VGA, then it does cable detection, so simply removing the cable is enough to turn off at least the output drivers.)

Re: QSB power

TedMichon — Thu, 03 Nov 2011 22:27:29 GMT

Thanks Phil. As soon as we have some success building the kernel, we will remove the video as you suggest.

-Ted

Re: QSB power

FernandoGinezd1 — Fri, 04 Nov 2011 17:29:29 GMT

I'm facing the same situation.
My system needs to be in standby (operating by batteries) during some days, and the power consuption is about 360mA (too high). Is there any command (or a driver to access the PMIC) to turn off these leds?
Thanks in advance!

Re: QSB power

PhilEndecott — Sat, 05 Nov 2011 23:10:15 GMT

> turn off these leds? A soldering iron, surely....

Re: QSB power

DominicS — Mon, 07 Nov 2011 16:06:31 GMT

Are you using ethernet? if not turn that off by removing ip=dhcp in uboot parameters.

Also, I would check if any update processes are running in the background, to pull kernel packages.