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3.9PinMultiplexing
3.9.1HardwareControlledPinMultiplexing
TMS320DM355
DigitalMediaSystem-on-Chip(DMSoC)
SPRS463A–SEPTEMBER2007–REVISEDSEPTEMBER2007
•Powermanagement
–DeepsleepandfastNANDbootcontrol
•BandwidthManagement
–BusmasterDMAprioritycontrol
FormoreinformationontheSystemControlModulerefertotheARMSubsystemUser'sGuide.
TheDM355makesextensiveuseofpinmultiplexingtoaccommodatethelargenumberofperipheral
functionsinthesmallestpossiblepackage.Inordertoaccomplishthis,pinmultiplexingiscontrolledusing
acombinationofhardwareconfiguration(atdevicereset)andsoftwarecontrol.Noattemptismadebythe
DM355hardwaretoensurethattheproperpinmuxinghasbeenselectedfortheperipheralsorinterface
modebeingused,thusproperpinmuxingconfigurationistheresponsibilityoftheboardandsoftware
designers.AnoverviewofthepinmultiplexingisshowninTable3-12.
Table3-12.PeripheralPinMuxOverview
PeripheralMuxedWithPrimaryFunctionSecondaryFunctionTertiaryFunction
VPFE(videoin)GPIOandSPI2VPFE(videoin)SPI2GPIO
VPBE(videoout)GPIO,PWM,andRTOVPBE(videoout)PWMandRTOGPIO
AEMIFGPIOAEMIFGPIOnone
ASP0GPIOASP0GPIOnone
MMC/SD1GPIOandUART2MMC/SD1GPIOUART2
CLKOUTGPIOCLKOUTGPIOnone
I2CGPIOI2CGPIOnone
UART1GPIOUART1GPIOnone
SPI1GPIOSPI1GPIOnone
SPI0GPIOSPI0GPIOnone
UsetheAsynchronousEMIFconfigurationpins(AECFG[3:0])forhardwarepinmuxcontrol.AECFG[3:0]
controlthepartitioningoftheAEMIFaddressesandGPIOsatreset,whichallowsyoutoproperly
configurethenumberofAEMIFaddresspinsrequiredbythebootdevicewhileunusedaddressespinsare
availableasGPIOs.ThesesettingsmaybechangedbysoftwareafterresetbyprogrammingthePinMux2
registerThePinMux2registerisintheSystemControlModule.AsshowninTable3-13,thenumberof
addressbitsenabledontheAEMIFisselectablefrom0to16.Pinsthatarenotassignedtoanother
peripheralandnotenabledasaddresssignalsbecomeGPIOs(exceptEM_A[2:1]).Theenabledaddress
signalsarealwayscontiguousfromEM_BA[1]upwards;bitscannotbeskipped.Theexceptiontothisare
EM_A[2:1].Thesesignals(canbeusedto)representtheALEandCLEsignalsfortheNANDFlashmode
oftheAEMIFandarealwaysenabled.NotethatEM_A[0]doesnotrepresentthelowestAEMIFaddress
bit.DM355supportsonly16-bitand8-bitdatawidthsfortheAEMIF.In16-bitmode,EM_BA[1]represents
theLSaddressbit(thehalf-wordaddress)andEM_BA[0]representstheMSaddressbit(A[14]).In8-bit
mode,EM_BA[1:0]representthe2LSaddressbits.Notethatadditionalselectionsareavailableby
programmingthePinMux2registerinsoftwareafterboot.NotethatAECFGselectionof‘0010’selects
OneNANDinterface.TheAEMIFneedstooperateinthehalf-ratemode(full_rate=0)tomeetfrequency
requirements.SoftwareshouldnotchangethePINMUX2registersettingtoaffecttheAEMIFrate
operation.AsoftresetoftheAEMIFshouldbeperformedanytimearatechangeismade.
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