Ethernet MAC
UG0331 User Guide Revision 15.0
377
11.2.1.3.6 PEMGT MII Management
The PEMGT sub-module drives the MII Management Interface where the control and status information
is exchanged with the attached PHY.
11.2.1.4 MAC Statistics Module
The MAC Statistics module is a register-based, statistics-gathering module. The MAC Statistics module
offers 37 separate counters, which can be used either to count or to accumulate conditions (such as
dropped frames which occur as packets), that are transmitted or received. The presence of non-zero
elements in either of these statistics vectors triggers MAC Statistics module to update its statistics
counters.
The counter’s rollover condition is indicated through a carry interrupt output from the MAC Statistics
module. Each counters rollover condition can be discreetly masked from causing an interrupt by internal
masking registers.
page 427 show the mask registers for transmit and receive.
11.2.1.5 SGMII Module
The SGMII module provides an SGMII that facilitates a connection between any IEEE 802.3 standard
GMII or MII interface and an SGMII interface that is compliant with version 1.7 of the SGMII specification.
The SGMII module uses TBI to provide the 8B/10B encoding, decoding, and auto-negotiation
functionality that is defined in Clause 36 of the IEEE 802.3z specification. This allows link partners to
synchronize with each other and exchange information regarding their configuration capabilities, using a
symbol stream that has a proven industry standard. The SGMII also instantiates transmit and receive
conversion and rate adaptation modules, which allow for G/MII data/control conversion, half-duplex
control encoding, and clock domain interfacing to the SGMII clock domain. The SGMII core includes
optional modules for 10-bit comma alignment.
Both transmit and receive paths leverage the physical coding sub-layer and the auto-negotiation sub-
layers of the IEEE 802.3z specification, as explained in clauses 36 and 37. In the transmit direction, the
10-bit encoded data is serialized and output over the interface. In the receive direction, the single-bit
input is made parallel after being aligned to comma characters.
The SGMII core also includes support for MAC speeds less than gigabit rates. To maintain a constant
clock frequency at the PHY interface for all MAC speeds, the MII bus data is replicated internally to
maintain a gigabit rate at the output of the SGMII core.
TSEMAC can have separate clocks for MSS and PHY side connections. These clocks are asynchronous
to each other.
11.3
TSEMAC PHY Interfaces
This section describes the MII, GMII, and TBI fabric PHY interfaces. The PHY interfaces (MII, GMII, and
TBI) are routed to the fabric onto MSIOs in case of MII, GMII, and SERDES I/Os in case of TBI. To
implement the other PHY protocols within the fabric such as RMII, RGMII, RTBI, RevMII, and SMII, these
PHY protocols may be derived from appropriate wrappers implemented in fabric, which converts PHY
interface signals input to the FPGA fabric as shown in
. The EMAC can be
configured through Libero SoC MSS configurator by selecting the interface, line speed, and enabling the
management interface PHY interface. On reset, MSS Ethernet MAC turns the auto-negotiate of the
Ethernet PHY to OFF. Due to difference in protocol between MSS Ethernet MAC and Ethernet PHY, user
has to handle the Ethernet PHY auto negotiation through PHY driver code. The SGMII can be
implemented by means of configuring the EMAC for the TBI operation. TBI pins are routed to SERDES,
which is configured for EPCS mode to provide SGMII functionality. as shown in
.
Содержание SmartFusion2 MSS
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