Idle
TX State
Idle
Setup
Interrupts
Interrupts
Interrupts
Interrupts
Interrupts
IN Data
Phase
IN Data
Phase
IN Data
Phase
Status Phase
(OUT)
Sequence #1
Sequence #2
Sequence #3
Setup
Interrupts
Interrupts
Interrupts
Interrupts
Interrupts
OUT Data
Phase
OUT Data
Phase
OUT Data
Phase
Status Phase
(IN)
Idle
RX State
Idle
CPU actions
Load FIFO &
Set TxPktRdy
Load FIFO &
Set TxPktRdy
Load FIFO &
Set TxPktRdy &
Set DataEnd
Unload Device Req.
& Clear RxPktRdy
CPU actions
UnLoad FIFO &
Clear RxPktRdy
Unload Device Req.
& Clear RxPktRdy
Unload FIFO &
Clear RxPktRdy
Unload FIFO &
Clear RxPktRdy
Set DataEnd
Interrupts
Status Phase
(IN)
Setup
Interrupts
Idle
CPU actions
Unload Device Req. &
Clear RxPktRdy &
Set DataEnd
(NO DATA Phase)
Functional Description
Figure 16-4. Sequence of Transfer
1705
SPRUH73H – October 2011 – Revised April 2013
Universal Serial Bus (USB)
Copyright © 2011–2013, Texas Instruments Incorporated