Xilinx Virtex UltraScale+ FPGAs

Each GTM transceiver features several loopback modes to facilitate tesng:
• Near-end PCS Loopback (Path 1 in the above gure). While in Near-end PCS Loopback, the RX
XCLK domain is clocked by the TX parallel clock (TX XCLK).
• Near-end PMA loopback (path 2 in the above gure).
• Far-end PCS Loopback (path 3 in the above gure). The transceiver in far-end PCS loopback
must use the same reference clock used by the transceiver that is the source of the loopbak
data.
Ports and Attributes
The following table denes the loopback ports.
Table 23: Loopback Ports
Port Dir
Clock
Domain
Description
CH[0/1]_LOOPBACK[2:0] In Async Loopback control for channel 0/1:
3’b000: Normal operation.
3’b001: Near-End PCS Loopback.
3’b010: Near-End PMA Loopback.
3’b011: Reserved.
3’b100: Reserved.
3’b101: Reserved.
3’b110: Far-End PCS Loopback.
The following table denes the loopback aributes.
Table 24: Loopback Attributes
Attribute Type Description
CH[0/1]_TX_LPBK_CFG0 16-bit Reserved. Use the recommended value from the Wizard.
CH[0/1]_TX_LPBK_CFG1 16-bit Reserved. Use the recommended value from the Wizard.
Dynamic Reconfiguration Port
The dynamic reconguraon port (DRP) allows the dynamic change of parameters of the
GTM_DUAL primives. The DRP interface is a processor-friendly synchronous interface with an
address bus (DRPADDR) and separate data buses for reading (DRPDO) and wring (DRPDI)
conguraon data to the primives. An enable signal (DRPEN), a read/write signal (DRPWE), and
a ready/valid signal (DRPRDY) are the control signals that implement read and write operaons,
indicate operaon compleon, or indicate the availability of data.
Chapter 2: Shared Features
UG581 (v1.0) January 4, 2019 www.xilinx.com
Virtex UltraScale+ GTM Transceivers 47
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