Mac transmit datapath, Mac transmit datapath -4 – Altera Triple Speed Ethernet MegaCore Function User Manual
Page 40
• Avalon-ST on the system side.
• Avalon-ST sink port on transmit with the following properties:
• Fixed data width, 8 bits, in MAC variations without internal FIFO buffers; configurable data width,
8 or 32 bits, in MAC variations with internal FIFO buffers.
• Packet support using start-of-packet (SOP) and end-of-packet (EOP) signals, and partial final
packet signals.
• Error reporting.
• Variable-length ready latency specified by the
tx_almost_full
register.
• Avalon-ST source port on receive with the following properties:
• Fixed data width of 8 bits in MAC variations without internal FIFO buffers; configurable data
width, 8 or 32 bits, in MAC variations with internal FIFO buffers.
• Backpressure is supported only in MAC variations with internal FIFO buffers. Transmission stops
when the level of the FIFO buffer reaches the respective programmable thresholds.
• Packet support using SOP and EOP signals, and partial final packet signals.
• Error reporting.
• Ready latency is zero in MAC variations without internal FIFO buffers. In MAC variations with
internal FIFO buffers, the ready latency is two.
• Media independent interfaces on the network side—select MII, GMII, or RGMII by setting the Interface
option on the Core Configuration page or the
ETH_SPEED
bit in the
command_config
register.
• Control interface—an Avalon-MM slave port that provides access to 256 32-bit configuration and status
registers, and statistics counters. This interface supports the use of
waitrequest
to stall the interconnect
fabric for as many cycles as required.
• PHY management interface—implements the standard MDIO specification, IEEE 803.2 standard Clause
22, to access the PHY device management registers. This interface supports up to 32 PHY devices.
MAC variations without internal FIFO buffers implement the following additional interfaces:
• FIFO status interface—an Avalon-ST sink port that streams in the fill level of an external FIFO buffer.
Only MAC variations without internal buffers implement this interface.
• Packet classification interface—an Avalon-ST source port that streams out receive packet classification
information. Only MAC variations without internal buffers implement this interface.
Related Information
•
on page 4-15
•
on page 7-1
•
MAC Configuration Register Space
on page 6-1
•
More information about the Avalon interfaces.
MAC Transmit Datapath
On the transmit path, the MAC function accepts frames from a user application and constructs Ethernet
frames before forwarding them to the PHY. Depending on the MAC configuration, the MAC function could
perform the following tasks: realigns the payload, modifies the source address, calculates and appends the
Functional Description
Altera Corporation
UG-01008
MAC Transmit Datapath
4-4
2014.06.30