Xilinx 7 Series User Manual page 152

Chapter 4: Receiver
Figure 4-22
bus contains the data samples, and each bit of the 40-bit Sdata bus is one if and only if the
corresponding data sample and offset sample are not equal. (See ES_ERRDET_EN in
page
X-Ref Target - Figure 4-22
Rdata
PMA
Interface
Sdata
Two consecutive cycles of Sdata are masked by ES_SDATA_MASK[79:0] (i.e., bit-by-bit Sdata[i]
AND NOT mask[i]). The algebraic sum of bits [39:0] of this result is the number of errors to be
added in the error counter.
Two consecutive cycles of Rdata are compared with the pattern in ES_QUALIFIER[79:0], and that
result is masked by (i.e., bit-by-bit ORed with) ES_QUAL_MASK[79:0]. The logical AND of this
result determines whether the prescaler/sample counter is incremented and the errors added to the
error counter. For a statistical eye, ES_QUAL_MASK is 80'b1, so the sample counter and error
counter accumulate on every cycle. ES_SDATA_MASK unmasks only the current data (bit 39 and
below; see the description of RX_DATA_WIDTH) to avoid double counting errors because they
appear first in the lower 40 bits and then in the upper 40 bits on the next cycle.
Alternate use modes produce scope-like displays by unmasking a sequence of Rdata bits (up to 20),
causing error and sample accumulation only if Rdata matches ES_QUALIFIER in that range of bits.
In these use modes, only one Sdata bit per measurement is unmasked. In diagnostic use modes,
Rdata and Sdata are frozen and can be read out through the DRP interface when:
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152
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describes the portion of the PCS architecture that supports eye scan. The 40-bit Rdata
155.)
Filter
Count
FIFO
Qualifier
FIFO
Figure 4-22: PCS Architecture to Support Eye Scan
An error occurs,
A count qualifier occurs,
A fabric port causes a trigger, or
A trigger is forced via an attribute write.
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ES_VERT_OFFSET
ES_HORZ_OFFSET
Sample es_sample_count
Prescaler
Counter
Error
Counter
ES_SDATA_MASK
es_control_status
State
Machine
ES_EYE_SCAN_EN
7 Series FPGAs GTP Transceivers User Guide
Table 4-20,
ES_QUALIFIER
ES_QUAL_MASK
ES_PRESCALE
DRP
es_error_count
Interface
es_rdata
es_sdata
ES_CONTROL
ES_ERRDET_EN
UG482_c4_11_041012
UG482 (v1.9) December 19, 2016