USB ports.. the "how" and "why"..

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USB ports.. the "how" and "why"..

Postby Karlsweldt » Fri Feb 10, 2006 5:24 am

USB ports are not a mystery.. they work well, when connected right. But there are differences in the standards. The older USB port is considered as "Type 1", whereas the newer design is considered as "Type 2". What is the difference? Only in the speed at which the data is communicated! The ports and wiring of both are identical. There may be differences in the ads that declare the USB-2 port connections being the only ones to use, but that is not so! The older ports will work just fine, with the USB-2 standards. However, newer devices may list themselves as being only USB-2 compliant, and not work with older USB-1 setups. Read the requirements on the package or brochure. For older USB-1 devices, they will be recognized properly on USB-2 setups, and work properly. There is backward-compatiblity for USB ports, but not forward-compatibility. Some newer devices may work well on older USB-1 ports, but will so state in their requirements and the brochure that they are compatible. If it is not so stated, the device will not be recognized or work on older ports. You cannot "upgrade" an existing USB port. The chipset must be changed, which is near-impossible. Best to disable the on-board feature, and install a device card that has the new standards. Check the status of your USB ports from the 'control panel' System icon, hardware/device manager. There may be a controller for each USB port. There should be a notation about "USB2.0" or "enhanced" ports to denote the USB-2 type. Some mobos combine older USB-1 ports with newer USB-2 ports on the same mobo. The rear ports should be considered as being USB-2 standard. Again, the mobo handbook should detail their status.
Some very old Compaq systems had a non-standard USB port. Do not use these ports with modern devices.

The wire color for the USB header may be standardized, but the header pins may not be.
If the pinout configuration does not match your header, you stand a chance of destroying the USB device, or the USB controller/traces.
Check your mobo handbook, there should be diagrams of how the ports are configured.

Standard color-coding for USB ports:
Black, with different sheath than other leads.. shield lead, as ground only.
Black, as signal ground/power ground.
Green, as data (-) lead.
White, as data (+) lead.
Red, as Vcc or +5 volts.

The pin blocks may be set for parallel or staggered configuration. With a 10-pin connector, you may have to release the wire connector and place it in its appropriate slot. For those 10-pin headers, it is not required to use a second "shield" ground lead. One is sufficient.

For further information:
USB Port Standards.
USB "Everything".
USB cabling and mobo pinouts.
Karlsweldt
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Re: USB ports.. the "how" and "why"..

Postby olly » Fri Jul 14, 2006 1:12 pm

Karlsweldt wrote:Some newer devices may work well on older USB-1 ports, but will so state in their requirements and the brochure that they are compatible.


Not entirely true, I have loads of USB 2 devices that only mention being USB 2 compatible in their documentation and nothing about USB 1 at all, yet they work fine in USB 1 ports.
olly
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Postby Karlsweldt » Sat Jul 15, 2006 5:16 am

This link from everything USB should be self-explanatory. With any USB device, it may be adaptable to any USB port configuration.. or be restricted to specific fields of speed and recognition. The specs on the package or brochure will denote "for USB 2.0 only" or "compatible with all USB ports" in so many words, more or less. If a device can only be used on a USB 2.0 port, its data speed is set to one standard.. and is not backward-compatible. With the USB ports, there is backward-compatibility so any older device can be used with the newer standard, but some devices cannot be used on the older standard due to data speed.
If a device is not recognized on a USB 2.0 port, that will be due to the driver or device information file not being available. With any USB device that is newer than the OS inception date, or any device for that matter, drivers will be needed for recognition of its features/operation. It will be listed as an "unknown" device until the associated driver/inf file is presented to the OS.
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