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3.12.1HandlingFIFOOverrunConditioninTCICaptureMode
3.13VideoCaptureRegisters
VideoCaptureRegisters
5.WritetoTCISTCMPL,TCISTCMPM,TCISTMSKL,andTCISTMSKMifneededtoinitiateaninterrupt,
basedonSTCabsolutetime.
6.WritetoTCITICKSifaninterruptisdesiredeveryxcyclesofSTC.
7.WritetoVPCTLtoselectTCIcaptureoperation(TCI=1).
8.WritetoVPIEtoenableoverrun(COVRA)andcapturecomplete(CCMPA)interrupts,ifdesired.
9.WritetoVCACTLtosetcapturemode(CMODE=010).
10.SetVCENbitinVCACTLtoenablecapture.
11.CapturebeginsonthefirstVCLKINArisingedgewhenCAPENAandPACSTRTarevalid.AEDMA
eventisgeneratedastriggeredbyVCATHRLD1.Whentheentirepackethasbeencaptured
(DCOUNT=VCYSTOPandVCXSTOPcombinedvalue),theFRMCbitinVCASTATissetcausingthe
CCMPxbitinVPIStobeset.ThisgeneratesaDSPinterrupt,ifCCMPxisenabledinVPIE.
12.Ifcontinuouscaptureisenabled,thevideoportbeginscapturingagainonthenextVCLKINrising
edgewhenCAPENandPACSTRTarevalid.Ifnoncontinuouscaptureisenabled,thenextdatapacket
iscapturedduringwhichtheDSPmustcleartheFRMCbitorfurthercaptureisdisabled.Ifsingle
framecaptureisenabled,captureisdisableduntiltheDSPclearstheFRMCbit.
IncaseofaFIFOoverrun,theCOVRxbitissetinVPIS.ThisconditioninitiatesaninterrupttotheDSP,if
theoverruninterruptisenabled(settingtheCOVRxbitinVPIEenablesoverruninterrupt).
TheoverruninterruptroutineshouldsettheBLKCAPbitinVCxCTLanditshouldreconfigureEDMA
channelsettings.TheEDMAchannelmustbereconfiguredforcaptureofthenextframesincethecurrent
frametransferfailed.SettingtheBLKCAPbitflushesthecaptureFIFOandblocksEDMAeventsforthe
channel.AslongastheBLKCAPbitisset,thevideocapturechannelignorestheincomingdatabutthe
internaldatacountercontinuescounting.
TheBLKCAPbitshouldbeclearedto0inordertocontinuecapture.ClearingtheBLKCAPbittakeseffect
onthenextPACSTRT.(EDMAeventsarestillgoingtobeblockedintheTCIpacketinwhichtheBLKCAP
bitiscleared.)
TheregistersforcontrollingthevideocapturemodeofoperationarelistedinTable3-13.Seethe
device-specificdatasheetforthememoryaddressoftheseregisters.
Table3-13.VideoCaptureControlRegisters
Offset
Address
(1)
AcronymRegisterNameSection
100hVCASTATVideoCaptureChannelAStatusRegisterSection3.13.1
104hVCACTLVideoCaptureChannelAControlRegisterSection3.13.2
108hVCASTRT1VideoCaptureChannelAField1StartRegisterSection3.13.3
10ChVCASTOP1VideoCaptureChannelAField1StopRegisterSection3.13.4
110hVCASTRT2VideoCaptureChannelAField2StartRegisterSection3.13.5
114hVCASTOP2VideoCaptureChannelAField2StopRegisterSection3.13.6
118hVCAVINTVideoCaptureChannelAVerticalInterruptRegisterSection3.13.7
11ChVCATHRLDVideoCaptureChannelAThresholdRegisterSection3.13.8
120hVCAEVTCTVideoCaptureChannelAEventCountRegisterSection3.13.9
140hVCBSTATVideoCaptureChannelBStatusRegisterSection3.13.1
144hVCBCTLVideoCaptureChannelBControlRegisterSection3.13.10
148hVCBSTRT1VideoCaptureChannelBField1StartRegisterSection3.13.3
14ChVCBSTOP1VideoCaptureChannelBField1StopRegisterSection3.13.4
150hVCBSTRT2VideoCaptureChannelBField2StartRegisterSection3.13.5
(1)
Theabsoluteaddressoftheregistersisdevice/portspecificandisequaltothebaseaddress+offsetaddress.Seethe
device-specificdatasheettoverifytheregisteraddresses.
70VideoCapturePortSPRUEM1–May2007
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