[SOLVED] How usb works internally ?

[kdg007]

I read a lot about USB functions but i cannot find proper explanation about how Data is exchanged.For example if i connect a device like my iphone(or any other USB devices) to my computer ,how the computer recognises and how the D+ /D- in usb pins work to transfer the data ?



Thank you in advance @@

 

[nikhildascl]

The driver software installed in the PC, drives the datas, decode, encode and do what the function needed.

 

[ramesh007]

hi i think this could be the reason These USB
connectors let you attach everything from mice to printers to your
computer quickly and easily. The operating system supports USB as
well, so the installation of the device drivers is quick and easy, too.
Compared to other ways of connecting devices to your computer
(including parallel ports, serial ports and special cards that you
install inside the computer's case)When the host powers up, it queries all of the devices connected to the bus and assigns each one an
address. This process is called enumeration -- devices are also enumerated when they connect to
the bus.

 

[nikhildascl]

Have little help from here

 

[kdg007]

hmm... so what about the ID that i heard ...that when u connect a USB device to the computer,the device has to be recognised by the host(computer) for that it has an ID that will send to the computer.???
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1)Bulk - A device like a printer, which receives data in one big packet, uses the bulk transfer mode. A block of data is sent to the printer (in 64-byte chunks) and verified to make sure it's correct.
ans) ?? 64 bytes of chunks are 64 x 8 = 512 binary digits rights ? so which pin D+/D- of the usb cable does this operation ?

 

[nikhildascl]

I am not good in these thing so Wikipedia may help little and also look here

 

[kdg007]

thank you but i did looked into those things before..none of them have the complete explanation.

 

[nikhildascl]

That's right. Hope i can help more in future and i will collect more for you and i will post all those things here

---------- Post added at 21:58 ---------- Previous post was at 21:47 ----------

D+ and D- pins are data pins. The USB works on the principle of serial data transmission.

 

[kdg007]

when we are talking about data ..that means its current signals or voltage ? right ? 1010101 -> 1 is certain level of voltage and 0 is no voltage ...how much current is supplied through the D+/D- pins? and i understand the voltages are between 0 - 0.3 for low and 2.8 to 3.6 for high
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this is what i am trying to understand,in engineering level--> how the currents,voltages work while the data transmission through D-/D+ PINS, WHEN THE USB DEVICE IS CONNECTED TO THE COMPUTER.
USB signals are transmitted on a twisted-pair data cable with 90Ω ±15%(how did they came up with this value ???????????????)

 

[nikhildascl]

https://www.geoffknagge.com/uni/elec101/essay.shtml

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It uses max 5.2V i think and a current max upto 500mA.

 

[kjm]

u can get a usb specification sheet from usb.org . This will solve all your doubts for sure.