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3.2.1.1SetupPhase
Transaction
scheduled
TxPktRdy
and SetupPkt
both set
?
SETUP token sent
DATA0 oacket sent
?
received
Stall
No
Yes
Yes
No
RxStall set
TxPktRdy cleared
Error Count cleared
interrupt generated
Command not
supported by
target
TxPktRdy cleared
Error Count cleared
Interrupt generated
Yes
?
No
ACK
received
Transaction
complete
No
NAK
received
?
Yes
?
NAK limit
reached
No
Yes
Error count
cleared
incremented
Error count
NAK Timeout set
Endpoint halted
Interrupt generated
?
Error
count=3
No
Error bit set
TxPktRdy cleared
Error Count cleared
interrupt generated
Yes
Implies problem
at peripheral end
of connection.
Transaction deemed
complete
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USBControllerHostandPeripheralModesOperation
FortheSETUPPhaseofacontroltransaction(Figure9),thesoftwaredrivingtheUShostdeviceneeds
to:
1.Loadthe8bytesoftherequiredDevicerequestcommandintotheEndpoint0FIFO.
2.SetSETUPPKTandTXPKTRDY(bits3and1ofHOST_CSR0,respectively).
Note:Thesebitsmustbesettogether.
ThecontrollerthenproceedstosendaSETUPtokenfollowedbythe8-bytecommandtoEndpoint0of
theaddresseddevice,retryingasnecessary.(Onerrors,controllerretriesthetransactionthreetimes.)
Figure9.SetupPhaseofaControlTransactionFlowChart
SPRUGH3–November2008UniversalSerialBus(USB)Controller45
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