Freescale Semiconductor TWR-MCF52259-Ethenet User Manual page 91

How Data is Transferred in USB
USB is a token-based (packet) standard. Data is transferred
between the host and the device in a series of frames, transfers,
transactions, and packets within1 Ms/1500 byte frames.
Frame
TM
Transfer 1 Transfer 2 Transfer 3
Transaction Transaction 1 Transaction 2 Transaction 3 Transaction 1
1500 bytes / 1 Ms