TM
Software – General Concepts
The General USB Process
How Data is Transferred in USB
For each transaction there are three types of packets that
communicate the data between host and device:
Transaction Transaction
Packet 1
Packet 2
Packet 3
Packet 1
Packet 2
Packet 3
1. Token Packet – the header that defines what follows
2. Optional Data Packet – contains the data being transmitted
3. Status/Handshake Packet – used to acknowledge transactions
and provide a means of error correction