Functional Description of the EMAC
Figure 17-2: EMAC High-Level Block Diagram with Interfaces
Master
Interface
DMA
Controller
TX FIFO Buffer
Controller
RX FIFO Buffer
Controller
RX FIFO Buffer
(DPRAM)
MAC
PHY
Interface
EMAC
Slave
Interface
Operation Mode
Register
DMA
CSRs
TX FIFO Buffer
(DPRAM)
There are two host interfaces to the MAC. The management host interface, a 32-bit slave interface, provides
access to the CSR set. The data interface is a 32-bit interface. It controls data transfer between the direct
memory access (DMA) controller channels and the rest of the HPS system through the NIC 301 L3
interconnect.
There is a built-in DMA controller which is optimized for data transfer between the MAC controller and
system memory. The DMA controller has independent transmit and receive engines, and a CSR set. The
transmit engine transfers data from system memory to the device port, while the receive engine transfers
data from the device port to the system memory. The controller uses descriptors to efficiently move data
from source to destination with minimal host intervention.
The EMAC also contains FIFO buffer memory to buffer and regulate the Ethernet frames between the
application system memory and the EMAC controller. On transmit, the Ethernet frames read into the
transmit FIFO buffer (1024 x 42 bits), and eventually trigger the MAC to perform the transfer. Received
Ethernet frames are stored in the receive FIFO buffer, also indicating the FIFO buffer bits fill level to the
DMA controller. The DMA controller then initiates the configured burst transfers. Both receive and transmit
transfer status are taken from the MAC and transferred to the DMA.
Host Interfaces
There are two host interfaces in the EMAC: a slave and a master. The master is connected to the L3 master
peripheral switch interface in the L3 interconnect block.
Slave
The EMAC CSR set access is provided by a slave interface. The slave is connected to the level 4 (L4) bus.
Altera Corporation
Ethernet Media Access Controller
17-9
Functional Description of the EMAC
cv_54017
2013.12.30