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4.68NAKLimit0Register(Hostmodeonly)(HOST_NAKLIMIT0)
4.69TransmitIntervalRegister(Hostmodeonly)(HOST_TXINTERVAL)
Registers
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TheNAKLimit0Register(Hostmodeonly)(HOST_NAKLIMIT0)isshowninFigure83anddescribedin
Table84.
Figure83.NAKLimit0Register(Hostmodeonly)(HOST_NAKLIMIT0)
7540
ReservedEP0NAKLIMIT
R-0R/W-0
LEGEND:R/W=Read/Write;R=Readonly;-n=valueafterreset
Table84.NAKLimit0Register(Hostmodeonly)(HOST_NAKLIMIT0)FieldDescriptions
BitFieldValueDescription
7-5Reserved0Reserved
4-0EP0NAKLIMIT0-1FhSetsthenumberofframes/microframes(high-speedtransfers)afterwhichEndpoint0shouldtime
outonreceivingastreamofNAKresponses.Thenumberofframes/microframesselectedis2
(—1)
(wheremisthevaluesetintheregister,validvalues2-16).IfthehostreceivesNAKresponses
fromthetargetformoreframesthanthenumberrepresentedbytheLimitsetinthisregister,the
endpointwillbehalted.
Note:Avalueof0or1disablestheNAKtimeoutfunction.
TheTransmitIntervalRegister(Hostmodeonly)(HOST_TXINTERVAL)isshowninFigure84and
describedinTable85.
Figure84.TransmitIntervalRegister(Hostmodeonly)(HOST_TXINTERVAL)
70
POLINTVL_NAKLIMIT
R/W-0
LEGEND:R/W=Read/Write;-n=valueafterreset
Table85.TransmitIntervalRegister(Hostmodeonly)(HOST_TXINTERVAL)FieldDescriptions
BitFieldValueDescription
7-0POLINTVL_NAKLIMIT0-FFhForInterruptandIsochronoustransfers,definesthepollingintervalforthe
currently-selectedtransmitendpoint.ForBulkendpoints,thisregistersetsthenumberof
frames/microframesafterwhichtheendpointshouldtimeoutonreceivingastreamofNAK
responsesThereisatransmitIntervalregisterforeachconfiguredtransmitendpoint
(exceptEndpoint0).Ineachcasethevaluethatissetdefinesanumberof
frames/microframes(HighSpeedtransfers),asfollows:
TransferTypeSpeedValidvalues(m)Interpretation
InterruptLowSpeedorFullSpeed1-255Pollingintervalismframes
HighSpeed1-16Pollingintervalis2
(—1)
microframes
IsochronousFullSpeedorHighSpeed1-16Pollingintervalis2
(—1)
frames/microframes
BulkFullSpeedorHighSpeed2-16NAKLimitis2
(—1)
frames/microframes
Note:Avalueof0or1disablestheNAKtimeoutfunction.
130UniversalSerialBus(USB)ControllerSPRUGH3–November2008
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