USB Hub Issues....

[inov8tr]

There is a lot of discussion about self powered vs. bus powered USB hubs. This seems to be some what of a problem in my installation and I was hoping someone could shed some light. Mike... You mentioned the Belkin hub at the bottom of the P5V page had a switch on it so you could select the power. USB hubs available now seem to be "smart" and do the thinking for you on which power they should use. GRRRRR!!!

My issues are two fold. First I had my MacMini running this evening with the 7" Lilliput and the USB hub was plugged into the MacMini. The external power cable for the USB hub was leading off to the P1900. I noticed a little red light on in the P1900. Since the P1900 is sitting on my desk, not plugged into anything but the USB hub via the P5V, this seemed bad. Unplugging the external power plug from the USB hub turned the light off in the P1900. So my USB hub is back-feeding the P1900, I'm sure the P1900 isn't going to be "belching flames" from this since it is pretty stout. But this is really frustrating!!!

I decided to take the USB hub apart and cut the incoming 5v line from the computer, that was a bad idea... Now only the power light for the hub comes on when you plug it into the wall, but rest of the status lights for the individual ports do not light up. (No flaming please, everyone has to learn their lesson at some point) So, the thing needs the 5v from the computer to operate properly. Well this is no good since I don't want to feed it 5v from the computer. I'll have to solder that lead back on tomorrow.

So the two questions from this long winded story are:

Does anyone know of a hub that truely only runs on external power or at least has a switch so I can do the thinking for the hub???

And, what are the ramificatons of the USB hub back feeding the P1900, once I actually install it in my car and power the P1900???

Any help is much appreciated....

-David

[mikeh]

David,

I'm not sure how in the world the LED on the P1900 can be lit by an external voltage applied to the P5V....??? This does not make sense to me. However, I don't believe it will damage the P5V or P1900.

It does sound like you may have a USB hub that takes power from EITHER the external input OR the bus, which ever is ON. The only experience I have is with the Belkin, which has a power selector switch.

[inov8tr]

Do you have the model number of the Belkin that you are using so that I can try and find one. The Belkin website doesn't have anything that looks like that so maybe they have stopped making them, or I'm looking the in the wrong place.

Thanks....

[mikeh]

The model number is F5U014. The hub is about 2 yrs old.

[inov8tr]

Mike,

Thanks for all your help. After a little further investigation of my USB Hub I came up with a solution. It is a little more unconventional, but it has worked really well. Don't know that it is recommended for everyone, but it has worked for my installation. I wanted to post it in case it will help anyone else out.

Here is a link to my CarMac project, specific with photos and a description of the fix.

http://inov8tr.blogs.com/scooby/2006...b_solutio.html

[mikeh]

Outstanding! Your work is very well done. Thanks for sharing with us. Good job on isolating your power issues in the USB hub. How about posting a link to your project in our "Your Projects" section? Also, I'm sure the Mac users at MP3Car would love to see your work.

Thanks again!

[di5crete]

inov8tr, I was wondering how the power flows though out the hub at this point.

Does the power light ONLY on the hub stay on when you connect hub to computer ONLY?
Does your usb devices connected to the ports ONLY receive power when you have the external power source connected?
What lights stay on the hub when your computer is sleeping and external power source is unplugged?

Thanks for your help in advance.

[inov8tr]

Originally Posted by di5crete

inov8tr, I was wondering how the power flows though out the hub at this point.

Does the power light ONLY on the hub stay on when you connect hub to computer ONLY?
Does your usb devices connected to the ports ONLY receive power when you have the external power source connected?
What lights stay on the hub when your computer is sleeping and external power source is unplugged?

Thanks for your help in advance.

--When ONLY the computer is connected to the hub there are no lights on.
--When ONLY the external power is connected just the power light comes on, NONE of the individual port power lights.
--The USB devices connected to the ports ONLY receive power with the external supply, but they only function when both the computer and the external supply are plugged in and powered.
--The USB hub must be feed by the computer and the external 5v for all of the lights to be on and everything to function.
--When the computer is sleeping and the external supply is disconnected/powered down all the lights are off on the USB hub.
--It is impossible to wake the computer from sleep via a USB device when the external supply is disconnected/powered down because even though the processor inside the USB hub is still powered the devices plugged in are not powered.
--If the computer goes to sleep and the USB hub continues to receive power via the external 5v, all of the lights will stay on and it is possible to wake the computer from sleep via a USB device (i.e. touching the touch screen).

Hope this helps, let me know if you have any other questions....

-David

[di5crete]

David thank you very much. You answered any possible questions I had. I purchased the 4-port version of the d-link hub, but the circuitry is very differnt than the one you worked with. So I will now be purchasing the 7-port version and will do exactly what you did.

Thanks again for your support.

[inov8tr]

Cool, happy I could help out. Just make sure you skip the step where I cut the pin off of the USB plug and had to repair it. That should make your modifications go pretty quick, because then you only have to cut the trace on the board...

Good luck!!!