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1.3FunctionalBlockDiagram
Configuration bus
DMA memory
transfer controller
Peripheral bus
EMAC control module
EMAC module MDIO module
MII bus MDIO bus
EMAC/MDIO
interrupt
DSP interrupt
controller
Introduction
Figure1showsthethreemainfunctionalmodulesoftheEMAC/MDIOperipheral:
•EMACcontrolmodule
•EMACmodule
•MDIOmodule
TheEMACcontrolmoduleisthemaininterfacebetweenthedevicecoreprocessorandtheEMAC
moduleandMDIOmodule.TheEMACcontrolmodulecontainsthenecessarycomponentstoallowthe
EMACtomakeefficientuseofdevicememory,plusitcontrolsdeviceinterrupts.TheEMACcontrol
moduleincorporates8K-byteinternalRAMtoholdEMACbufferdescriptors.
TheMDIOmoduleimplementsthe802.3serialmanagementinterfacetointerrogateandcontrolupto32
EthernetPHYsconnectedtothedevice,usingasharedtwo-wirebus.HostsoftwareusestheMDIO
moduletoconfiguretheautonegotiationparametersofeachPHYattachedtotheEMAC,retrievethe
negotiationresults,andconfigurerequiredparametersintheEMACmoduleforcorrectoperation.The
moduleisdesignedtoallowalmosttransparentoperationoftheMDIOinterface,withverylittle
maintenancefromthecoreprocessor.
TheEMACmoduleprovidesanefficientinterfacebetweentheprocessorandthenetworkedcommunity.
TheEMAConthisdevicesupportsboth10Base-T(10Mbits/sec),and100BaseTX(100Mbits/sec),in
eitherhalf-duplexorfull-duplexmode,withhardwareflowcontrolandquality-of-service(QOS)support.
Figure1alsoshowsthemaininterfacebetweentheEMACcontrolmoduleandtheCPU.Thefollowing
connectionsaremadetothedevicecore:
•TheperipheralbusconnectionfromtheEMACcontrolmoduleallowstheEMACmoduletoreadand
writebothinternalandexternalmemorythroughtheDMAmemorytransfercontroller.
•TheEMACcontrolmodule,EMAC,andMDIOallhavecontrolregisters.Theseregistersare
memory-mappedintodevicememoryspaceviathedeviceconfigurationbus.Alongwiththese
registers,thecontrolmodule’sinternalRAMismappedintothissamerange.
•TheEMACandMDIOinterruptsarecombinedintoasingleinterruptwithinthecontrolmodule.The
interruptfromthecontrolmodulethengoestotheDSPinterruptcontroller.
TheEMACandMDIOinterruptsarecombinedwithinthecontrolmodule,soonlythecontrolmodule
interruptneedstobemonitoredbytheapplicationsoftwareordevicedriver.ThecombinedEMAC/MDIO
interruptisconnectedtotheDSPinterruptINT43,throughtheDSPinterruptcontroller.
Figure1.EMACandMDIOBlockDiagram
12EthernetMediaAccessController(EMAC)/SPRU941A–April2007
ManagementDataInput/Output(MDIO)
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