1. USB uses differential s i g n als for data transmission. It improves the
noise immunity. USB interface has the ability 10 supply power to the
connecting devices. Two connection lines (Ground and Power) of the U 5
B interface an: dedicated for carrying power. It can supply power up to
500 mA at 5 V.USB supports four different types of data transfers,
namely: Control transfer, Bulk transfer. Isochronous tran s fer and I
nterrupt transfer

2. Control transfer is used by USB system software: to query, configure an
d issue commands to the USB device.

3. Bulk transfer is used for sending a block of data to a device. Bulk transfer
supports error checking and correction. Transferring data to a printer is
an example for bulk transfer.

4. Isochronousd ata_ transferis usedfor real-time data
communication. In Isochronous transfer, data is transmitted as a stream in
realtime, isochronous transfer doesn’t support error checking and _ re-
transmission of data in case of any transmission loss. All streaming devices
like audio devices and medical equipment for data collection make use of
the isochronous transfer.

5. Interrupt transfer is used for transferring small amount of data.
Interrupt transfer mechanism makes use of polling technique to see

whether the USB device has any data to send.