i want to know how usb port connection is interface with usb device
ie power to the device data input and output.

 

I suggest you start at the Wikipedia link.

Jan Axelson's books under "Further reading" are most recommended.

 

You're in for a very very long read.
The physical specification are quiet simple, the transfer protocol and enumeration methods required are.... Very complex. The USB 2.0 specification is over 650 pages long.

Full specifications can be found here.
http://www.usb.org/developers/docs/

 

You're in for a very very long read.
The physical specification are quiet simple, the transfer protocol and enumeration methods required are.... Very complex. The USB 2.0 specification is over 650 pages long.

<shrug> Never read it, but I've done several USB based apps.

Of course, a good code library is my best friend.

 

I have done 2 USB projects using readily available code as the basis.

waitingforfriday.com has a few USB projects and supplies circuit diagrams and software.

 

If the OP is trying to know about the power side of the USB connection, thats is not as difficult as the transactions involved.

 

Here is a good article on USB charging and specs.
http://www.extremetech.com/computin...ks-or-how-to-avoid-blowing-up-your-smartphone

 

The article is also incorrect. The standard allowance for USB ports is 100ma before enumeration regardless of it's version, to get more power out of a port a bus protocol request must be made regardless of USB version. USB 3.0 and USB on the go apparently after enumeration allow up to 1.8amps to be drawn only for power usage, 1.5amps is the limit if the communication lines are still used and that's only for low speed communication. High speed prohibits anything more than 100ma on the power lines during communication

Virtually every wall adapter and a large portion of USB root devices technically violate the USB specs when used as a charging port, and that doesn't even account for voltage variations.

 

The article is also incorrect. The standard allowance for USB ports is 100ma before enumeration regardless of it's version, to get more power out of a port a bus protocol request must be made regardless of USB version. USB 3.0 and USB on the go apparently after enumeration allow up to 1.8amps to be drawn only for power usage, 1.5amps is the limit if the communication lines are still used and that's only for low speed communication. High speed prohibits anything more than 100ma on the power lines during communication

Would you please site a source for your information. If you are going to contridict an official source you should list credible evidence to back up your statement.

 

i want to know how usb port connection is interface with usb device
ie power to the device data input and output.

The power is simply about 5 volts (usually between 4.8 and 5.2), and different versions are able to source different amounts of current. I once heard that 1.0 can source 100mA, 2.0 200mA, and 3.0 300mA, but I have since learned that it isn't that simple. But you get the idea, anyway.

The device drivers you install on your computer are what read the data on the USB port and tell the computer what to do from there.