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7.3.4PreservingBoundary-ScanFunctionalityonRGMIIandDDR2MemoryPins
TMS320C6454
Fixed-PointDigitalSignalProcessor
SPRS311A–APRIL2006–REVISEDDECEMBER2006
Peripheralsusedforbooting,likeI2CandHPI,areautomaticallyenabledafterdevicereset.Itisnot
possibletodisabletheseperipheralsafterthebootprocessiscomplete.
TheC64x+Megamodulealsoallowsforsoftware-drivenpower-downmanagementforalloftheC64x+
megamodulecomponentsthroughitsPower-DownController(PDC).TheCPUcanpower-downpartor
theentireC64x+megamodulethroughthepower-downcontrollerbasedonitsownexecutionthreadorin
responsetoanexternalstimulusfromahostorglobalcontroller.Moreinformationonthepower-down
featuresoftheC64x+MegamodulecanbefoundintheTMS320C64x+MegamoduleReferenceGuide
(literaturenumberSPRU871).
WhentheRGMIImodeoftheEMACisnotused,theDV
DD15
,DV
DD15MON
,V
REFHSTL
,RSV13,andRSV14
pinscanbeconnecteddirectlytoground(V
SS
)tosavepower.However,thiswillpreventboundary-scan
fromfunctioningontheRGMIIpinsoftheEMAC.Topreserveboundary-scanfunctionalityontheRGMII
pins,DV
DD15
,V
REFHSTL
,RSV14,andRSV13shouldbeconnectedasfollows:
•DV
DD15
andDV
DD15MON
-connectthesepinstothe1.8-VI/Osupply(DV
DD18
).
•V
REFHSTL
-connecttoavoltageofDV
DD18
/2.TheDV
DD18
/2voltagecanbegenerateddirectlyfromthe
DV
DD18
supplyusingtwo1-kΩresistorstoformaresistordividercircuit.
•RSV13-connectthispintoground(V
SS
)viaa200-Ωresistor.
•RSV14-connectthispintothe1.8-VI/Osupply(DV
DD18
)viaa200-Ωresistor.
Similarly,whentheDDR2MemoryControllerisnotused,theV
REFSSTL
,RSV11,andRSV12pinscanbe
connecteddirectlytoground(V
SS
)tosavepower.However,thiswillpreventboundary-scanfrom
functioningontheDDR2MemoryControllerpins.Topreserveboundary-scanfunctionalityontheDDR2
MemoryControllerpins,V
REFSSTL
,RSV11,andRSV12shouldbeconnectedasfollows:
•V
REFSSTL
-connecttoavoltageofDV
DD18
/2.TheDV
DD18
/2voltagecanbegenerateddirectlyfromthe
DV
DD18
supplyusingtwo1-kΩresistorstoformaresistordividercircuit.
•RSV11-connectthispintoground(V
SS
)viaa200-Ωresistor.
•RSV12-connectthispintothe1.8-VI/Osupply(DV
DD18
)viaa200-Ωresistor.
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