USB Hell, need help...

**jjakes24** · 04-20-2008, 01:56 PM

No matter what I do, I can't get all my USB devices to work at once. Here is my setup.
Infiniti G35 2003 coupe. Battery is less than a year old. Via 2.0 Gig PC, suppose to only take 20watts. M2-ATX DC-Dc converter. M2-ATX powers DVD drive at 5volts, Xenarc 705ts AT 12 Volts, and a 4 port USB hub rated at 5volts 2.1amps. Now, this is how I have everything hooked up. PC has six 2.0 USB ports. Two are used internally for Bluetooth and 802.1 Wireless. So that leaves me with 4 external ports. DVD-RW drive is powered externally and is plugged in directly to the PC by a 10ft USB Cable. The Hub is powered and hooked in directly to the PC by a 5m Active USB cable. Plugged into the hub are my ODB-II Reader and my Touchscreen. On the third USB port my GPS is plugged in. Now this is my problem. If I plug my DVD drive in, my touchscreen will work for a little but then disconnect. Sort of same thing is my ODBII is connected, if I hit on the gas, the ODBII is fine but then the touchscreen disconnects. If my DVD is plugged in alone, its fine, but if I plug other devices in, the DVD has problems reading discs or will disconnect. No matter what I do, I can't get them all to funtion together properly. I thought it might be a power problem but the hub is powered and almost everything is plugged in directly. Right now, I left my DVD and ODBII unplugged so the rest of my stuff can function but I would really like to have everything working together. I'm at a loss. I have engine noise too but think its unrelated and am picking up a ground isolator today. Can anyone help?

**JimmyFitz** · 04-20-2008, 05:19 PM

USB ports are usually limited to give up to .5A each at most. Optical drives usually need a bit more than 1 amp just to read properly. The first thing to suggest that you do is run the optical drive from a separate 5V feed, not from USB power. You can connect to the molex drive connectors off the PC power supply. Red is +5V, Black is ground. The second thing to suggest is that while you are at it, connect your powered hub to this same 5V supply so you can get more current from its ports.

**jjakes24** · 04-20-2008, 07:09 PM

Jimmy, this is already done and I thought I mentioned this in my first post. The drive and hub are powered by 5v from the PC. So in essence, its being powered by the m2-atx. This still leads me to my problems.

**JimmyFitz** · 04-20-2008, 08:33 PM

An active USB cable is for more length, not more current. From your description it isn't clear how you powered the drive or the hub. Most folks that have the kind of problem you describe resolve it by powering as I suggested. When you say you powered the drive externally, do you mean off another USB?

**SuperJ** · 04-20-2008, 08:41 PM

You're a little vague about how things are powered. Sounds like you need a hub with a separate power source (ie cig lighter)

**jjakes24** · 04-20-2008, 11:15 PM

Both the hub and DVD drive are powered by the 5 volt wires from the molex connectors on the PC's motherboard. Both the DVD Drive and hub had plugs for external power and I tested the wires with a meter so I know they are getting the 5 volts.

**JimmyFitz** · 04-20-2008, 11:47 PM

Perhaps there is a grounding issue. I am assuming that ground is also wired back to the molex? Maybe there is a faulty component in the mix.

**jjakes24** · 04-21-2008, 10:03 AM

Yes, ground is wired back to the molex. I get a power light from the hub, so if there was a faulty ground, would it even light up? I can double check the connections inside the PC case though.

**st1mpy** · 05-14-2008, 07:16 AM

I had this problem too, when I change all of the USB connections and put the Touchscreen in the first USB port.
My problem was the Touchscreen forgot his screensize and everytime calibration once I put it first no problem.

Try switching all of them. Hope it helps.

**almera** · 05-14-2008, 07:35 AM

Possible USB bandwidth problem?

How does a USB hub slow down devices?
A USB hub has to re-calculate the time left before the next sof (end of the uframe); the small extra delay added by the hardware hub could make the transaction not handled as fast as a device directly connected to the host. If several devices are connected on the hub and working in parallel (for example, a webcam + a USB flash drive + a mouse), then the USB bandwidth is shared among the devices usage.