Eye Outline Scan Mode; Ports And Attributes - Xilinx Virtex-6 FPGA User Manual

Chapter 4: Receiver

Eye Outline Scan Mode

This method provides diagnostic information related to the deterministic eye shape,
particularly the vertical eye opening. Setting RX_EYE_SCANMODE to 01 suspends the
DFE adaptation (if enabled). In this mode, DFEEYEDACMON provides a value between 0
and 31 that is proportional to the eye height at the phase offset determined by
RX_EYE_OFFSET.
This method measures the vertical opening corresponding to a high BER using the Scan
Sampler (see
taken into account. However, this method does not corrupt received data that continues to
be detected using the data sampler. Eye outline scan mode can thus be employed while
data continues to be received without error.
X-Ref Target - Figure 4-18

Ports and Attributes

Table 4-26
Table 4-26: RX Margin Analysis Ports
Port
RXDATA[31:0]
DFEEYEDACMON[4:0]
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212
Figure 4-16) so that no additional eye closure due to random jitter or noise is
E
100 mV
0 mV
–100 mV
Figure 4-18: Vertical Eye Height vs. RX_EYE_OFFSET
defines the RX margin analysis ports.
Dir Clock Domain
Out RXUSRCLK2 The user needs to detect data errors on RXDATA in order to monitor
the bit error rate of the link.
Out RXUSRCLK2 Average vertical eye height (voltage domain) used by the DFE as an
optimization criterion.
11111: Indicates approximately 200 mV
opening.
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D
0 0
RX_EYE_OFFSET
DFEEYEDACMON
Internal Eye Opening
Description
Virtex-6 FPGA GTX Transceivers User Guide
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1
UG366_c4_50_120809
of internal eye
PPD
UG366 (v2.5) January 17, 2011