Xilinx Virtex-6 FPGA User Manual

198 www.xilinx.com Virtex-6 FPGA GTX Transceivers User Guide
UG366 (v2.5) January 17, 2011
Chapter 4: Receiver
Table 4-12 defines the RX equalization attributes.
DFETAP3MONITOR[3:0] Out RXUSRCLK2 DFE tap 3 weight value monitor for each transceiver (3-bit
resolution plus 1-bit sign). For example, –2 is represented as
1 010.
DFETAP4[3:0] In RXUSRCLK2 DFE tap 4 weight value control for each transceiver (3-bit
resolution plus 1-bit sign). For example, –2 is represented as
1 010.
DFETAP4MONITOR[3:0] Out RXUSRCLK2 DFE tap 4 weight value monitor for each transceiver (3-bit
resolution plus 1-bit sign). For example, –2 is represented as
1 010.
DFETAPOVRD In RXUSRCLK2 Override enable for the DFE tap values.
0: Use the optimized DFE tap self-adapting values.
1: Override the DFE self-adapting values (recommended)
with the values provided by DFETAP1, DFETAP2,
DFETAP3, and DFETAP4.
RXEQMIX[9:0] In Async Receiver Equalization Control. Bits [9:3] are reserved. Only bits
[2:0] should be used.
The default is 3’b000, user specific.
Table 4-11: RX Equalizer Ports (Cont’d)
Port Dir Clock Domain Description
Table 4-12: RX Equalization Attributes
Attribute Type Description
DFE_CAL_TIME[4:0] 5-bit Binary DFE calibration time. Set to 01100 for normal operation (default).
DFE_CFG[7:0] 8-bit Binary DFE_CFG Description
[7:3] Limiter/EQAMP gain and power control
Set to 00011 (default)
[2:0] Vertical Eye measure AMP gain and power control.
Set to 011 (default)
RX_EN_IDLE_HOLD_DFE Boolean TRUE: Restores the DFE contents from internal registers after
termination of an electrical idle state for PCI Express operation. Holds
the DFE circuit in reset when an electrical idle condition is detected.
FALSE: (default)
Note: For channels with large attenuation (lossy channels typically
exceeding 15 dB at Nyquist), it is recommended that
RX_EN_IDLE_HOLD_DFE should be set to FALSE because fast
transitioning data patterns like the 101010 sequence in CJPAT/CJTPAT
can accidentally trigger an electrical idle
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Xilinx Virtex-6 FPGA Specifications

General

Brand	Xilinx
Model	Virtex-6 FPGA
Category	Transceiver
Language	English