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View Full Version : [Question(s)] VIA PX5000 and battery questions



anandoc
11-02-2008, 03:32 PM
Hello friends,

This is my first post in this forum (after having read various threads) so please be easy on me if I post in the wrong section.

I am a fresh electrical engineer and have been planning and designing a Windows based PC robot for personal learning around the VIA pico-ITX architecture. I have pretty much figured out all the basics except for powering the motherboard. I am not sure what kind of batteries to use for such a purpose (NiMH, LiPo, etc etc).

Also, I am not sure how to make the motherboard "battery-aware" so that Windows can see the status of the battery and shutdown gracefully when the juice runs low (just like how laptops do it). I have bee reading loads of stuff online but there doesnt seem to be any off-the-shelf solution or a relatively easy solution for a newbie.

Any help or tips from you gurus will be highly appreciated. I am just stunned at the amount of knowledge floating around here. Thanks.

A

DresnerRobotics
11-02-2008, 05:29 PM
I already answered your question via PM, but I'll put it out here for others to benefit from as well.

I'm using a 60w PicoPSU with a 6-26v input to power my Pico-ITX board, works great.

Not sure on the 'power aware' thing, I know exactly what you're talking about though. I haven't found a third party solution for it. You'd essentially need the charging circuit guts of a laptop methinks, but the battery monitoring seems to be inherent in Windows... not exactly sure how that one works.

anandoc
11-02-2008, 09:52 PM
Not sure on the 'power aware' thing, I know exactly what you're talking about though. I haven't found a third party solution for it. You'd essentially need the charging circuit guts of a laptop methinks, but the battery monitoring seems to be inherent in Windows... not exactly sure how that one works.

Thanks for your answer here and the PM. Laptops do the power aware thing through SMBus via a I2C port methinks. So I guess the charging unit in the laptop talks to the motherboard via the SMBus and there is a generic SMBus driver which tells windows about all the battery status/charging etc. Has anyone been able to rig anything like this for a mini/pico solution? It would be great to tell windows how much battery is remaining and to shutdown the PC gracefully if the juice is running out. Thanks.

Adrenalynn
11-02-2008, 11:42 PM
There's another option - Windows includes a UPS management solution over serial. The protocol is super simple, as memory serves - it's the method that APC and Cyberpower (among others) use.

Here we go!

http://www.networkupstools.org/protocols/apcsmart.html

So you could just simply measure the analog voltage with a voltage divider and a tiny microcontroller, and then kick back the voltage as a function of the divider. Use the UPS controls to execute a shutdown when you cross a threshold. You could report a properly formated voltage level string too and have near realtime display...

anandoc
11-03-2008, 01:47 PM
There's another option - Windows includes a UPS management solution over serial. The protocol is super simple, as memory serves - it's the method that APC and Cyberpower (among others) use.

Here we go!

http://www.networkupstools.org/protocols/apcsmart.html

So you could just simply measure the analog voltage with a voltage divider and a tiny microcontroller, and then kick back the voltage as a function of the divider. Use the UPS controls to execute a shutdown when you cross a threshold. You could report a properly formated voltage level string too and have near realtime display...

That definitely looks like an option, and I had come across it while doing my research. However, it looks quite dirty. I am surprised that there are no pre-built solution for something like this and there definitely isnt much info available there either. The SMBus route looks more elegant. Maybe I will have to rip open a old laptop and see how the charging module talks to the motherboard.

Adrenalynn
11-03-2008, 02:54 PM
Well, I think it depends how you define "dirty". You're going to have to measure and report voltage either way. Both Windows Power Management and UPS Management are services under Windows.

So it comes down to which bus you send the data over. Since it's not high-speed/high-density data, the argument that sending it over a UART offloads the CPU could also be made - and then the solution becomes "less dirty" than the SMBus solution.

[shrug] Six of one, half dozen of the other, IMHO.

DresnerRobotics
11-03-2008, 03:17 PM
That definitely looks like an option, and I had come across it while doing my research. However, it looks quite dirty. I am surprised that there are no pre-built solution for something like this and there definitely isnt much info available there either. The SMBus route looks more elegant. Maybe I will have to rip open a old laptop and see how the charging module talks to the motherboard.


Mobile computers outside of laptops are a relatively new thing on the market, doesn't surprise me that there isn't much support for it

anandoc
11-03-2008, 05:27 PM
Mobile computers outside of laptops are a relatively new thing on the market, doesn't surprise me that there isn't much support for it

Thanks guys for your input. Tyberius, what make/model of battery are you using in your project to power up the pico-ITX? Thanks.

DresnerRobotics
11-04-2008, 10:02 AM
9.6v 4200mAh NiMH from batteryspace.com (http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2803)

robot maker
11-05-2008, 08:09 PM
one way you get do it is use a voltage divider to A-D INPUT on a microcontroller with usb output and write a code for it
on batteries i seem to like LI-PIO types mostly because of the weight, does have a few drawbacks ,one is hard to charge them,CV and CA charging design,second is they dont last too long,but alot of laptops are using them,weight is biggest problem i see in robots,more weight,more more torque and more amps is used,and have a longer run time before charged,also smaller size then other types of batteries


Hello friends,

This is my first post in this forum (after having read various threads) so please be easy on me if I post in the wrong section.

I am a fresh electrical engineer and have been planning and designing a Windows based PC robot for personal learning around the VIA pico-ITX architecture. I have pretty much figured out all the basics except for powering the motherboard. I am not sure what kind of batteries to use for such a purpose (NiMH, LiPo, etc etc).

Also, I am not sure how to make the motherboard "battery-aware" so that Windows can see the status of the battery and shutdown gracefully when the juice runs low (just like how laptops do it). I have bee reading loads of stuff online but there doesnt seem to be any off-the-shelf solution or a relatively easy solution for a newbie.

Any help or tips from you gurus will be highly appreciated. I am just stunned at the amount of knowledge floating around here. Thanks.

A

anandoc
01-16-2009, 08:28 PM
Hello again!

I have finally managed to acquire all the parts for my first tracks based robot (a HUGE thanks to Tyberius!).

I was playing around with the picoITX with Windows XP booted up and all and was measuring the wattage on that thing and I found out that with a 2.5" SATA drive and a USB Wifi dongle connected, my pico was only consuming about .20 A of current @ 19.75V. Even with cpuburn (running CPU at 100%), I could only bump the amperage upto a meagre .22A . This would mean that my pico is consuming 19.75V x .22A = 4.345 Watts. Thats real tiny!

I am measuring the current going into the picoPSU. Did you guys get similar numbers or am I doing something completely wrong here? Oh and I also dont have the heatsink/fan on top of it. Any feedback from ya'll would be much appreciated!

DresnerRobotics
01-16-2009, 09:07 PM
I was pulling around 13w from my 1ghz Pico-ITX. 4-5w sounds about right for the ULV 500mhz version.

Pretty cool that you can run it without a heatsink/fan though eh?

Adrenalynn
01-16-2009, 10:18 PM
The spin-up on the drive is where you'll some some substantial power drain (1A @ 5v is about average for a 5400RPM 2.5" SATA). On a read/write cycle, I'd expect 2watts and a half watt at idle - give or take.

anandoc
01-17-2009, 08:36 AM
I did extensive file copy operations to the 2.5" hard drive from the network and yet the total consumption from the picoPSU end was only .2A @ 19.75V. I just couldnt get the current to bump over .22A @19.75V. Are there any other tests that I can perform to sort of get a "worst case scenario" current usage?

Adrenalynn
01-17-2009, 03:14 PM
I think that's about the worst. And to an extent it makes sense.
1A @ 5v = 0.25A @ 20v. Of course, there's loss in any conversion, but that is a low-loss power supply intended for automobile use. I'd question the accuracy of your meter in the hundredths place.

But just use my rule of thumb: whatever you're reading in your worst imaginable case - double it. Boom. There you go, half an amp.

If you're stepping down to 12v on your final bot you'll need to test again, of course, and if you're stepping up to 24v, ditto the test again.