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2.8
EMAC Module
2.8.1
EMAC Module Components
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
2.8.1.1
Receive DMA Engine
2.8.1.2
Receive FIFO
Architecture
This section discusses the architecture and basic function of the EMAC module.
The EMAC module (
Figure 11
) interfaces to the outside world through the Media Independent Interface
(MII) and interfaces to the system core through the EMAC control module. The EMAC consists of the
following logical components:
•
The receive path includes: receive DMA engine, receive FIFO, and MAC receiver
•
The transmit path includes: transmit DMA engine, transmit FIFO, and MAC transmitter
•
Statistics logic
•
State RAM
•
Interrupt controller
•
Control registers and logic
•
Clock and reset logic
Figure 11. EMAC Module Block Diagram
The receive DMA engine is the interface between the receive FIFO and the system core. It interfaces to
the CPU through the bus arbiter in the EMAC control module. This DMA engine is totally independent of
the device DMA.
The receive FIFO consists of 68 cells of 64 bytes each and associated control logic. The FIFO buffers
receive data in preparation for writing into packet buffers in device memory, and also enable receive FIFO
flow control.
Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO)
38
SPRUEQ6 – December 2007
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