hello guys
i read online that usb 2.0 support only half duplex communication(data can pass only in one direction at a time)
but when i try to read a file from my sandisk flash drive(2.0) and write another one to it at the same time ,no error occur
does not this oppose the half duplex theory
thank you

 

No it does not. Do you think the the guys that came with the USB bus would be so daft that you could only ever do one operation at a time until the first one was finished? Of course not.
USB is kind of similar to ethernet in the way that there are packets of data being transmitted at a time. The USB host controls the whole operation, so it for example first sends a few packets of data from the computer to the flash drive, then it tells the flash drive that it is now allowed to transmit its few packets of data back to the computer.
This switches back and forth until all transfers are done, and since the swaps of who is transmitting are very fast it looks like both are doing it at the same time, but in fact they are taking turns because the USB bus can only transmit one way at a time.

 

i read online

Error detected.

 

Technically correct, practically useless.

See time sharing