Xilinx 7 Series User Manual page 155

Table 4-20: RX Margin Analysis Attributes (Cont'd)
Attribute
ES_SDATA_MASK
ES_QUALIFIER
ES_QUAL_MASK
ES_EYE_SCAN_EN
Binary
ES_ERRDET_EN
Binary
7 Series FPGAs GTP Transceivers User Guide
UG482 (v1.9) December 19, 2016
Type
80-bit This attribute masks up to two cycles of the 40-bit Sdata bus. Binary 1 causes the corresponding
Hex bus bit to be masked and binary 0 leaves it unmasked. To support the statistical eye view, the error
counter accumulates the total number of unmasked 1s on the most recent cycle of the Sdata bus
(masked by ES_SDATA_MASK[39:0]). To support the scope and waveform views, the error
counter increments by only one for any non-zero number of unmasked 1s on the previous cycle of
the Sdata bus (masked by ES_SDATA_MASK[79:40]).
This attribute and ES_QUAL_MASK must also mask out unused bits. For the statistical eye view,
this attribute would assume the following values as a function of bus width:
20-bit width: ES_SDATA_MASK = (40'b1, 20'b0, 20'b1)
16-bit width: ES_SDATA_MASK = (40'b1, 16'b0, 24'b1)
Scope and waveform views require a sequence of measurements, unmasking only a single bit per
measurement.
80-bit Eye scan can qualify BER measurements based on patterns up to 20 contiguous bits long in any
Hex position in the input data. Because the data, and therefore the qualifier pattern, is not aligned, the
position of the pattern must be discovered by a barrel-shifting search. For example, looking for the
pattern 10'b0011111010 (K28.5 in 8B/10B code) with a 20-bit data width would require a
sequence of measurements such as the following, searching for a non-zero sample count at the
correct alignment:
ES_QUALIFIER = (50'b?, 10'b0011111010, 20'b?)
ES_QUALIFIER = (49'b?, 10'b0011111010, 21'b?)
ES_QUALIFIER = (48'b?, 10'b0011111010, 22'b?)
...etc... (where ? represents a DON'T CARE bit that will be masked)
The qualifier pattern is shifted only over the valid bits for the bus width (40, 32, 20, or 16).
80-bit This attribute masks those bits not included in the qualifier pattern. For example, the corresponding
Hex values for the K28.5 example above would be:
ES_QUAL_MASK = (50'b1, 10'b0, 20'b1)
ES_QUAL_MASK = (49'b1, 10'b0, 21'b1)
ES_QUAL_MASK = (48'b1, 10'b0, 22'b1)
...etc...
1-bit This bit should always be 1 when using eye scan. Setting this bit to 0 powers down the eye scan
circuitry in the PMA and forces the eye scan state to WAIT. Re-enabling eye scan functionality
requires reasserting this bit and asserting/deasserting PMA reset.
1-bit 1: Each bit of the Sdata bus is 1 if and only if the corresponding offset data sample does not agree
with the recovered data sample. This is used for the statistical eye view.
0: Each bit of the Sdata bus is the recovered data sample. Therefore, if no errors occurred, the Sdata
bus would be identical to the Rdata bus. This is used for the scope and waveform views.
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RX Margin Analysis
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