going to run some cat5 cable to use for USB cams.. how many USB can i make from the 8 wires? USB 1.0 used only 2 wires for signal and 2 for power but USB 2.0 apparently uses the connector chassis for a 5th connection. can that be shared? say for a double or triple USB gang? or must be completely isolated such that only two USB can be created with 8 wires.
3+3+2(power)
USB is a serial device bus, 'gang' boy.
What's your point, Dum-Dum?
I do not believe you can share power, at least in general, since usb devices have special power modes to detect when they are on and off.
In your case it may not matter.
I would suggest you try it. At most you will burn your usb port up. Also, Many devices can be powered without using the usb supply so that is a possible option.
My only concern would be the power issue. I believe usb ports have current limiting so it's probably not a big deal if it were an issue at all.
each cam uses 2 usb data lines, a common ground and power which means you'll need 2(n + 1) lines. For 8 wires this will allow 3 cams.
I've not heard of the USB 2.0 using more than 4 wires. USB 3 will double the data lines but it is fully backwards compatible.
On a sunny day (Fri, 23 Dec 2011 08:56:37 -0500) it happened JW wrote in :
To the defense .. would make more sense to put the hub at the end of the line no?
no? would like to pack 2-3 small cams into a standard AC box so will not be room for a bub.
i will be powering all (2-3) USB devices with an external 5v supply which i am prettty sure can be connected paralell to all the connectors
i was of the impression that usb 2.0 cables require the case/chassis of the usb connectors to be attached to the shield (or 5th wire) otherwise is considered usb1.0 by the machine.
no?
How long is the cable you are attempting to use? There's a limitation of 5 meters for USB 2.0
am aware , thanks.
There are active cables.
IIRC- the USB signaling is differential, two wires (twisted pair) for Data + and Data- (3.3V levels) with a +5V and Ground and the whole thing shielded. USB on the go (OTG) is five wires. I haven't used it so far so don't know much about it.
Cat 5 has four twisted pairs and no shield. I'm sure it voids the specifications greatly but may be worth a try. Without the shield, you will probably get RF leakage. All I can say is do a test with the length of cable you intend to use before you make it permanent. A portable AM radio is useful for getting a ballpark estimate of RF leakage. It's going to be broadband.
Some USB equipment senses +5V to determine if something is present. Others only detect that a termination is present.
If you haven't done it yet, check out
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OTG is just TO GROUND or NOT TO GROUND pin 4. Not a problem with bandwidth.
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