Solved: USB bus stays powered after shutdown

S4Per · 04-13-2004, 06:35 PM

Hi All,
We had a thread on this the other day, and the solution I implemented is slightly different than the one that was proposed.

Problem: USB bus stays powered even after Opus shuts down computer, thereby draining the battery. Secondly - I needed to power my USB hub.

Solution: I have 6 USB ports on the Shuttle, but unfortunately the 4 on the back of the computer are integrated into the board. The two front ones are not, and therefore have a cable that connects the ports to the mobo. Here - we spliced in a relay for the two USB ports (splicing into the power lines) that is powered by the molex connector. So - power is supplied to the bus only when the hard drive (for example) is powered. In essence, as soon as the computer shuts down, so does power to the bus. The second relay is essentially the same, except that it's for the 5v line that runs from another molex connector to the USB hub. So - power is supplied to the hub only when the computer is on.

It's essentially like the solution that was drawn up on the other thread, but note that no diode's, and therefore no drop in voltage, were necessary to do this. It works like a charm.

Thanks for all of the help and suggestions.

-Per

MSUC5Vette · 04-14-2004, 07:05 PM

Just curious, why did you decide not to use the relay?

S4Per · 04-14-2004, 07:39 PM

Not sure what you mean. I used two relay's, but no diode's.

So, relay 1: from HD connector to 2 front USB ports (power down ports when computer shuts down), and
Relay 2: from HD connector to USB hub power (power down hub when computer shuts down).

-Per

Ricky327 · 04-15-2004, 03:23 PM

S4Per read shchua post #31 on :

http://www.mp3car.com/vbulletin/show...t=24507&page=3

Its a protection diode and you do need it...theres no voltage lost concern in that.

You dont wanna risk damaging your PSU, HDD or anything thats connected to that relay coil...I did say dont miss that diode...and do connect it the right way.

Glad you got it working anyway.

S4Per · 04-15-2004, 03:28 PM

a-ha...thanks much for the pointer. looks like i'll need to get that in there. thanks again!

UncleGeek · 04-17-2004, 08:02 AM

Do you need BOTH 5V power sources? Would this work with using only one relay on either the hub external power supply or the 5v power off the motherboard USB connector feeding the hub? Thereby eliminating one or the other power source?

S4Per · 04-17-2004, 10:30 AM

I needed to do 2 things:
1. Make sure that when the computer is off, no power gets supplied to the bus, and
2. Make sure that when the computer is off, no power is being supplied to the 'external' power supply of the USB hub.

So - two different things, therefore 2 relays.

HTH,
Per

MSUC5Vette · 04-17-2004, 02:05 PM

Quote: Originally Posted by S4Per

I needed to do 2 things:
1. Make sure that when the computer is off, no power gets supplied to the bus, and
2. Make sure that when the computer is off, no power is being supplied to the 'external' power supply of the USB hub.

So - two different things, therefore 2 relays.

HTH,
Per

Others who are considering doing this may want to look for a DP (Double Pole) relay. In this application a DP would do the same job as two relays, but would save some wiring etc. You would connect the bus to one pole, and the PS to the other.

Is anyone doing anything similar to this to control the power to their monitor? This way if you wanted to have the screen on when the car is off, but the computer running, but not supply power to the monitor to save the battery you could.

UncleGeek · 04-17-2004, 02:24 PM

S4Per,
Do you HAVE to have two seperate sources for power and why?

MUSC5vette,
I currently use a relay to power up/down my LCD display.

Ricky327 · 04-17-2004, 04:51 PM

http://www.maplin.co.uk/Search/results.asp?CartId=040417214534929&Level=1&Menu=18 &Name=Relays

As MSUC5Vette advised :

Yes use DPDT relays on the list and save a diode too

tom2112 · 04-18-2004, 09:54 AM

OK, maybe I'm dumb, but wouldn't it be easier to just use a powered USB hub (12 volt of course). Hook the powered hub to the ACC line, so it's only on when the car is on or in accessory mode. You'd also need to cut the USB cable that runs from the motherboard to the USB hub, severing the 5v feed, but leaving the data connections. That way no power is drawn from the motherboard, only the ACC line for USB devices plugged into the hub. This way you could plug your GPS (for instance) directly into the motherboard, so it's always powered, and your USB DVD drive into the hub, so it's only powered while the car is on.

Does that make sense? Or am I missing something?

TIA,
Tom

Ricky327 · 04-18-2004, 10:38 AM

OK, maybe I'm dumb, but wouldn't it be easier to just use a powered USB hub (12 volt of course).

NO

Because you will loose the power to the USB devices as soon as you take the key out. Shutdown controller do have some delay before shutting down as soon as the ignirion is gone.

What if the PC is trying to write to the USB HDD before shutting down? but you already took the power away from it?

I guess, yes it can work for some setup

UncleGeek · 04-18-2004, 11:03 AM

tom2112,
Thank you for posting what I was trying to ask.

Ricky327,

Quote:

NO

...

I guess, yes it can work for some setup

Thanks for clearing this up.

mbkowns · 04-18-2004, 01:06 PM

Quote: Originally Posted by Ricky327

OK, maybe I'm dumb, but wouldn't it be easier to just use a powered USB hub (12 volt of course).

NO

Because you will loose the power to the USB devices as soon as you take the key out. Shutdown controller do have some delay before shutting down as soon as the ignirion is gone.

What if the PC is trying to write to the USB HDD before shutting down? but you already took the power away from it?

I guess, yes it can work for some setup

just wire it to your car alarm then when you chirp your car its off and when you chirp chirp is on

simple and easy and i really hope most of you have a car alarm of some sort with this expensive hardware

......

I want to wire my car computer to my alarm hmm adding a usb hub lets see

1. Chirp Chirp ( ON ) > turn on carputer with the Power-SW pinouts + a relay to turn on the usb hub.

2. Chirp ( OFF ) > turn off carputer with the Power-SW pinouts + a relay to turn off the usb hub.

Also if you didn't want to wire it directly to the unlock/lock function of your car alarm alot of them have a accessory feature like the clifford ones do. **** you could even do this! one to turn on / turn off and one to reset the carputer.

How cool would that be! Just make sure you arm your car most of us do but you could also wire a itps so if forget it kills the power.

Cool also if your in your house and you want to sync some music over just power it on (remote start would be better for this though) and copy over and power down.

dashpc · 04-18-2004, 09:49 PM

The DSSC startup / shutdown controller will solve this easily. It has a master relay that completely pulls power to the PC. It solves these USB issues.

You can see it over at:
http://www.dashpc.com/

Click on the DSSC circuit link.

Best regards,
CB