2.8EMACModule
2.8.1EMACModuleComponents
Clock and
reset logic
Receive
DMA engine
Interrupt
controller
Transmit
DMA engine
Control
registers
Configuration bus
EMAC
control
module
Configuration bus
RAM
State
FIFO
Receive
FIFO
Transmit MAC
transmitter
Statistics
receiver
MAC
SYNC
2.8.1.1ReceiveDMAEngine
2.8.1.2ReceiveFIFO
Architecture
ThissectiondiscussesthearchitectureandbasicfunctionoftheEMACmodule.
TheEMACmodule(Figure11)interfacestotheoutsideworldthroughtheMediaIndependentInterface
(MII)andinterfacestothesystemcorethroughtheEMACcontrolmodule.TheEMACconsistsofthe
followinglogicalcomponents:
•Thereceivepathincludes:receiveDMAengine,receiveFIFO,andMACreceiver
•Thetransmitpathincludes:transmitDMAengine,transmitFIFO,andMACtransmitter
•Statisticslogic
•StateRAM
•Interruptcontroller
•Controlregistersandlogic
•Clockandresetlogic
Figure11.EMACModuleBlockDiagram
ThereceiveDMAengineistheinterfacebetweenthereceiveFIFOandthesystemcore.Itinterfacesto
theCPUthroughthebusarbiterintheEMACcontrolmodule.ThisDMAengineistotallyindependentof
thedeviceDMA.
ThereceiveFIFOconsistsof68cellsof64byteseachandassociatedcontrollogic.TheFIFObuffers
receivedatainpreparationforwritingintopacketbuffersindevicememory,andalsoenablereceiveFIFO
flowcontrol.
EthernetMediaAccessController(EMAC)/ManagementDataInput/Output(MDIO) 38SPRUEQ6–December2007
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