OK USB gurus...

EdFred

EdFred

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I could have saved myself some time had I tried this first, at least I know what the problem is, now how to fix it?

I have a Lilliput UM-80/C/T an 8" USB LCD Touch Screen Monitor. It has the mini USB jack that connects to it. The other end of the cable is a Y connector with the standard USB connection on each fork. I am attempting to connect this to a Viliv S5 running XP SP2.

The problem, only 1 USB port on the Viliv. No problem I'll get a 4 port hub because I have the USB GPS antenna that goes into this, and if I got the XM add on, they will connect with a hub as well. Well, after a few hours of uninstall reinstall I finally figured out that I can not plug both ends of the Y into the hub and plug the hub into a single USB port (figured that out, by testing on a desktop with two usb ports, and testing the 4 different configurations). So, it appears that without doing anything radical I can not have both of the Y cable ends finish off in a single USB port.

Suggestions? Hacks?
 
Is it possible that there's too much current draw for a single USB? Would a powered hub make a difference? (If so, how would you power it in flight? But that's a separate question.)
 
I think Grant's onto it - USB hub will sometimes work without external power, but usually need it for more than one device.

What voltage does the external power input for the USB hub want?
 
Bang.


Head.



Wall.



Until.




It.



Turns.




To.




Pulp.



Yes, that appears to be the problem.
 
Easy problem to fix. Dish details.
 
Agree. The only good reason that the touchscreen would need two USB ports is because they can't get enough power off one port.
 
SCCutler said:
Easy problem to fix. Dish details.
Click to expand...

Time to call the A/P to see what approval is needed to put the USB port on airplane power. If I do that, I may as well put the S5 on it too.
 
The two Type "A" ends usually are just to provide additional power to the device. In fact, one of them may provide only power (the rest of the connectors on the "extra" connector would be dead-ended and go nowhere in this case).

Does the screen only work when one or the other Type "A" connectors is used, or when either of them (but not both) are used?

-Rich

EDIT: Good grief... I don't think as many posts have EVER been made while I was making a single post...
 
RJM62 said:
The two Type "A" ends usually are just to provide additional power to the device. In fact, one of them may provide only power (the rest of the connectors on the "extra" connector would be dead-ended and go nowhere in this case).

Does the screen only work when one or the other Type "A" connectors is used, or when either of them (but not both) are used?

-Rich

EDIT: Good grief... I don't think as many posts have EVER been made while I was making a single post...
Click to expand...

One cable powers the monitor, the other controls the touch screen - or so it seems.
 
EdFred said:
One cable powers the monitor, the other controls the touch screen - or so it seems.
Click to expand...

That's possible if it's a proprietary cable, in which case I'd still agree that the problem is excessive power draw. But most twin-A to Mini-5 cables are just for extra power.

There are adapters for cars that have a USB jack with the proper voltages to charge cell phones and power other USB devices. Some of them just plug into the accessory plug / cigarette lighter and have a single USB port with only the power leads active. I have no idea if there's such a thing approved for aircraft use.

-Rich
 
It'd be pretty simple to power everything you needed off of the 12 or 24V power outlet you have. Just depends how clean you want the install I guess.
 
jesse said:
It'd be pretty simple to power everything you needed off of the 12 or 24V power outlet you have. Just depends how clean you want the install I guess.
Click to expand...

Sure, it would be dead simple for anyone who knows anything about electricity. But would it be legal?

-Rich
 
Actually, a USB connector only provides 5 volts, now that I think about it. Firewire is the confusing one.
 
RJM62 said:
Sure, it would be dead simple for anyone who knows anything about electricity. But would it be legal?

-Rich
Click to expand...
Yes. Plugging something into the outlet is not permanent.
 
I am curious - where does the monitor get the video signal ?
Is it over the USB, or is there a separate VGA or DVI connector ?

As others have said, it is likely that the monitor has 2 USBs to consume 2x the power of a standard USB port. USB ports are spec'd to have a +5 Volt power rail and can provide up to 500mA on that rail. That's only 2.5Watts per port... and many USB ports cannot provide that much power.

As a side note, I am surprised the monitor works at all without external power. 2 x 2.5W = 5W isn't much for an 8" backlit screen.

Anyway, back to your setup. Most likely you are going to need a USB hub with external power. I suspect that most externally powered USB hubs use a 5VDC input voltage from the wall transformer. It should be easy enough to find a cigarette lighter adapter that converts +12 to +5VDC to drive the USB hub. You can then use a Y-adapter on the cigarette lighter to power both the PC and the USB hub cigarette lighter adapters. I ran into this same issue, and frankly, it starts to be a kludge of cables to get everything powered. Cigarette lighters are the worst format ever for transferring power.

Edit: One more comment. You may want to check out the carputer and MP3car forums, as they have had to deal with this same problem, I'm sure...
 
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jesse said:
Yes. Plugging something into the outlet is not permanent.
Click to expand...
Correct. The only "legal" question is whether or not the 12v outlet (cigar lighter socket etc) is "legally" installed. If the USB hub power cable were wired directly to the aircraft bus that cable (assuming it's detachable from the hub) would need approval which shouldn't be hard to get if it's properly protected against overload (many A&Ps wouldn't give a second thought to signing off on that as a minor alteration).
 
Dropped the plane off at the avionics shop about 15 minutes ago.

To answer the questions. Yes the monitor runs only on dual plug USB interface. No vga, no dvi, just usb. After talking with the guys at the avionics shop what we are going to do is just install 2 female cigarette adapter plugs hidden behind the panel. I will go to radio shack and get another dc adapter to power the hub. All the power cords should remain hidden and the only cords that should be seen are the usb and the power from the S5, but those will disapper into the panel under the transponder. I am going to get a second piece of aluminum drill 2 holes in it to mount it in the panel and then cut 4 keyhole slots and slide in the monitor next to the 430. The usb hub will get tucked and velcroed up under the panel, and everything should look clean and tidy. And I will have an empty and usable cig adapter in the panel to use for somethiing else.
 
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