DS537 Datasheet, PDF (109/148 Pages) Xilinx, Inc – LogiCORE IP XPS LL TEMAC

LogiCORE IP XPS LL TEMAC (v2.03a)
Loopback
There are two possible loopback positions:
• Loopback in the Hard TEMAC silicon component. When placed into loopback, data is routed from the
transmitter to the receiver path at the last possible point in the PCS/PMA sublayer. This is immediately before
the RocketIO transceiver interface. When placed into loopback, a constant stream of Idle code groups is
transmitted through the RocketIO transceiver. Loopback in this position allows test frames to be looped back
within the system without allowing them to be received by the link partner (the device connected on the other
end of the Ethernet. The transmission of Idles allows the link partner to remain in synchronization so that no
fault is reported.
• Loopback in the RocketIO transceiver. The RocketIO transceiver can be switched into loopback and will route
data from the transmitter path to the receiver path within the RocketIO transceiver. However, this data is also
transmitted out of the RocketIO transceiver and so any test frames used for a loopback test will be received by
the link partner.
Loopback can be enabled or disabled by writing to the SGMII Management Control Register bit 14 (Table 100 on
page 117) while the loopback position can be controlled by writing the SGMII Management Loopback Control
Register bit 0 (Table 111 on page 122).
1000BASE-X PCS/PMA
Please refer to UG194 Virtex-5 FPGA Embedded Tri-Mode Ethernet MAC User Guide for an equivalent diagram of
the clock management scheme when the XPS_LL_TEMAC parameter C_INCLUDE_IO = “1”. When the parameter
C_INCLUDE_IO = “0”, MGTCLK_P connects directly to the RocketIO GTP/GTX; hence the IBUFDS is not used.
PCS/PMA
The Physical Coding Sublayer (PCS) for 1000BASE-X operation is defined in IEEE 802.3 clause 36 and 37 and
performs the following:
• Encoding (and decoding) of GMII data octets to form a sequence of ordered sets
• 8B/10B encoding (and decoding) of the sequence ordered sets
• 1000BASE-X Auto-Negotiation for information exchange with the link partner
The Physical Medium Attachment (PMA) for 1000BASE-X operation is defined in IEEE 802.3 clause 36 and
performs the following:
• Serialization (and de serialization) of code-groups for transmission (and reception) on the underlying serial
PMD
• recovery of clock from the 8B/10B coded data supplied by the PMD
1000BASE-X PCS/PMA functionality is provided by connecting the Hard TEMAC silicon component to a RocketIO
transceiver.
PMD
The Physical Medium Dependent (PMD) sublayer is defined in IEEE 802.3 clause 38 for 1000BASE-LX and
1000BASE-SX (long and short wave laser). This type of PMD is provided by the external GBIC or SFP optical
transceiver which should be connected directly to the ports of the RocketIO transceiver.
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