User manual

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How Data is Transferred in USB
Frame
Transfer 1
Transaction
Start of Frame
Transfer 2
Transaction 1
Packet 1 Packet 2 Packet 3
Transaction 2
Packet 1 Packet 2 Packet 3
Transaction 3
Packet 1 Packet 2 Packet 3
Transfer 3
Transaction 1
Packet 1 Packet 2 Packet 3
1500 bytes / 1 Ms
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.
Software – General Concepts