Here's the deal. I added a radioshack USB hub to my system because I was running out of ports and I wanted to hook up my USB wireless adapter. The hub can be self powered (can't support the wifi adapter in this mode - too much current) as well as take 5v from the supplied adapter. I hacked off the AC end of the cable and hooked it up to the 5v rail from the opus, so it's drawing its 5v at up to 2.4A from the Opus.
However, I have one problem. The wifi adapter and most other devices will power on and then immediately shut off when they detect that there is not enough power available to them. I don't know how they do this, but they do, and it's a hardware thing not software - this all happens within a split second.
When I turn on the system, the hub comes right on, as do the USB devices, then they power off just like they would if the hub was self-powered (not enough power). Now, if I unplug all the devices and plug them back in everything works fine. Best I can tell, here's what's happing. The OPUS is powering up the USB 5v a split second before it powers up the 5v rail that is supplying the extra current to the hub, and in that split second, the USB devices have time to power up, think there's not enough power (5v rail hasn't been energized) and shut off. Shortly after, the 5v rail comes on and it can fully support everything once I unplug and replug all of the devices.
Is there any way I can make this work? I figure I just need to make the hub wait until the 5v rail is powered up before it turns on. I figured I would do this by cutting the 5v+ from the usb cable so it didn't have power until it got it from the 5v rail, but when I do this Windows doesn't even recognize the hub. For some reason it needs to be drawing power from the USB 5v line to be recognized. I verified this on other computers as well.
Can anyone figure out a solution?
Thanks in advance,
are you using WinXP or Win2k?
2007 Honda Fit Sport 1.5L SOHC-VTEC
Originally Posted by MrPerfectionest
It hasn't. This all happens within a split second. Like I said, this is a hardware problem, not software. There is not enough power for all the USB devices once the 5v USB bus comes up, so they shut off. Nothing to do with Windows turning them off. And they won't come back on (and stay on) until the extra current is available from the 5v rail. Once it's there, they'll stay on fine. I just don't want to have to unplug and replug every USB device every time I turn the car on...
Does that make sense?
Ugh. Did you read my post? I HAVE enough power, it's just not getting supplied right.Originally Posted by Montanaja
Again... I think the easiest fix would be a 5v POL.
You could try wiring your 5v from your opus directly to the usb connection for your usb hub (obviously disconnecting the existing usb power supply first..)??
It seems a bit weird that the hub doesn't work when the 5v usb supply is disconnected and the hub is running on an external supply (never tried it before).
Re-boxed Dell Optiplex GX110 PIII 733 256Mb RAM
Modified Sproggy PSU
Custom made automatic start-up/ shut-down controller
Dual 2.5" HDDs
Laptop DVD Reader
D-Link FM Radio
5" PSOne LCD
Installed and working. 75% complete.