Freescale Semiconductor TWR-MCF52259-Ethenet - Manual (Page 110)

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The General USB Process
Frames in More Detail
Each frame begins with a Start of
Frame packet followed by the
hosts transactions to device
endpoints for data transfer.
The host may schedule
transactions anywhere in the
frame, but they must complete
within the frame.
The host schedules
transactions within 1mS
frames for low and full
speed.
Token Data Handshake
Transfers may span
multiple frames.
Control, Interrupt,
Bulk,
Isochronous
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1 Ms Frame
Transfer 1
Transaction
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Transfer 2
Transaction 1
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t 1
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t 2
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t 3
Transaction 2
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t 1
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t 2
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t 3
Transaction 3
P
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t 1
P
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t 2
P
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t 3
Transfer N
Transaction 1
P
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t 1
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t 2
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t 3
U
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Transfer 1
Transaction
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