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5.6General-PurposeInput/Output(GPIO)
5.6.1GPIOPeripheralInput/OutputElectricalData/Timing
TMS320DM355
DigitalMediaSystem-on-Chip(DMSoC)
SPRS463A–SEPTEMBER2007–REVISEDSEPTEMBER2007
TheGPIOperipheralprovidesgeneral-purposepinsthatcanbeconfiguredaseitherinputsoroutputs.
Whenconfiguredasanoutput,awritetoaninternalregistercancontrolthestatedrivenontheoutputpin.
Whenconfiguredasaninput,thestateoftheinputisdetectablebyreadingthestateofaninternal
register.Inaddition,theGPIOperipheralcanproduceCPUinterruptsandEDMAeventsindifferent
interrupt/eventgenerationmodes.TheGPIOperipheralprovidesgenericconnectionstoexternaldevices.
TheGPIOpinsaregroupedintobanksof16pinsperbank(i.e.,bank0consistsofGPIO[0:15]).There
areatotalof7GPIObanksinthe,becausethehas104GPIOs.
TheGPIOperipheralsupportsthefollowing:
•Upto1043.3vGPIOpins,GPIO[103:0]
•Interrupts:
–Upto10uniqueGPIO[9:0]interruptsfromBank0
–Upto7GPIO(bankaggregated)interruptsignals,onefromeachofthe7banksofGPIOs
–Interruptscanbetriggeredbyrisingand/orfallingedge,specifiedforeachinterruptcapableGPIO
signal
•DMAevents:
–Upto10uniqueGPIODMAeventsfromBank0
–Upto7GPIO(bankaggregated)DMAeventsignals,onefromeachofthe7banksofGPIOs
•Set/clearfunctionality:Firmwarewrites1tocorrespondingbitposition(s)tosetortoclearGPIO
signal(s).ThisallowsmultiplefirmwareprocessestotoggleGPIOoutputsignalswithoutcriticalsection
protection(disableinterrupts,programGPIO,re-enableinterrupts,topreventcontextswitchingto
antherprocessduringGPIOprogramming).
•SeparateInput/Outputregisters
•Outputregisterinadditiontoset/clearsothat,ifpreferredbyfirmware,someGPIOoutputsignalscan
betoggledbydirectwritetotheoutputregister(s).
•Outputregister,whenread,reflectsoutputdrivestatus.This,inadditiontotheinputregisterreflecting
pinstatusandopen-drainI/Ocell,allowswiredlogicbeimplemented.
FormoredetailedinformationonGPIOs,seetheDocumentationSupportsectionfortheGeneral-Purpose
Input/Output(GPIO)ReferenceGuide.
Table5-10.TimingRequirementsforGPIOInputs(seeFigure5-12)
DM355
NO.UNIT
MINMAX
1t
w(GPIH)
Pulseduration,GPIxhigh52ns
2t
w(GPIL)
Pulseduration,GPIxlow52ns
Table5-11.SwitchingCharacteristicsOverRecommendedOperatingConditionsforGPIOOutputs
(seeFigure5-12)
DM355
NO.PARAMETERUNIT
MINMAX
3t
w(GPOH)
Pulseduration,GPOxhigh26
(1)
ns
4t
w(GPOL)
Pulseduration,GPOxlow26
(1)
ns
(1)Thisparametervalueshouldnotbeusedasamaximumperformancespecification.Actualperformanceofback-to-backaccessesofthe
GPIOisdependentuponinternalbusactivity.
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