Battery Power for xu4?

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Re: Battery Power for xu4?

Unread postby memeka » Sun Mar 26, 2017 8:29 pm

Using the HW encoder you can reduce CPU usage a lot. You can probably get 1080p resolution with less CPU usage.
Capping big cores at 1.6 would greatly increase battery life. Power usage is not linear e.g. From 1.8Ghz to 2Ghz you get 10% speed increase but >20% power usage, made worse by higher temps as cooling will also use power.
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Re: Battery Power for xu4?

Unread postby cdhinrichs » Mon Mar 27, 2017 7:33 am

Thanks, mad_ady.

I didn't know that about the 1st 4 cores vs the last 4. Maybe I can set those to "performance" and leave the last 4 as "conservsative". I like the idea of writing it up as a project, but I'm still developing the concept. If the point were to record video, I'd be mostly done, and in that case your suggestion to use hardware encoding is a good one. But what I really want is to try to do some real-time computer vision stuff, which needs raw frames. The purpose of doing software H.264 is really to see how much I can push the CPUs while on battery. And, I think I can push them a little further.

I didn't know about the "MFC" encoder / decoder hardware. The words "encode" and "decode" do not occur anywhere in the XU4 user manual. Neither does "MFC", but there is a word about an "XMBC". If I can get a camera to stream H.264, and then decode raw frames in hardware, then that would expand my range of choices for cameras - a lot of the "GoPrO" style outdoor cameras that have wider FOV and HDR rely on onboard H.264 encoding - you can either download the video later, or it can stream H.264, but no raw frames.

Running specific jobs on specific CPUs is good info, thanks.
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Re: Battery Power for xu4?

Unread postby cdhinrichs » Mon Mar 27, 2017 10:50 am

Hi memeka,

With my setup, I have about 75 Amp-hours of battery, so at the rated 5A for the odroid, that's 15 hours, and even at 7.5A that's still 10 hours. The difficulty really has been getting a sufficient amp draw, and controlling the ramp-up so that the batteries could cope with it.

But, I didn't know about the hardware encoder, which is very valuable to know since even once I go ahead with my computer vision project, it would still be great to have a way to save the outputs.
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Re: Battery Power for xu4?

Unread postby fassl » Wed Dec 20, 2017 5:03 am

jacky wrote:Hey,

Think that by using these cables:
http://www.amazon.com/Power-Enhancer-Fe ... le+femelle
http://www.amazon.com/niceeshop-Barrel- ... +%2F+2.1mm

And connect 2 usb on this battery
http://www.amazon.com/Upgraded-Capacity ... r+16750mAh
on 2.1A and 2.4A.

It should also work?


Thank you for this awesome tip, i can confirm that it works! I could even boot off just one of the above 2A ports and run a cpu stress test for a while without it dropping out. I then connected it with a Y adapter to the 2.1A and 1A ports (didn't read the manual) and ran stress --cpu 16 for 3-4 hours without a dropout. I did this on the debian image without manually disabling cores or adjusting frequencies so i cannot make a reason out of some problems described here, or is the debian image maybe preconfigured for this?

Another interesting thing is, the odroid can be turned on after a previous shutdown with the battery meter button! If we can make this trigger fire when the battery itself is replugged into power or the power is back one could make the odroid power up automatically, this would be awesome... Does anyone with more electrincs skill may have me a hand at this? I thought about using a monostable vibrater to trigger the poweron gpio pin if that is possible. But if a battery meter (turn odroid off on low capacity) would require the battery to be modified anyway one might just try to make the power is back trigger trigger the batteries battery meter button. I am a noob at this, i would be really greatful for any tips or pointings in the right direction.

cheers
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