Xilinx 7 Series User Manual page 166

Chapter 4: Receiver
Ports and Attributes
Table 4-25
Table 4-25: RX Byte and Word Alignment Ports
Port Name
RXBYTEISALIGNED
RXBYTEREALIGN
RXCOMMADET
RXCOMMADETEN
RXPCOMMAALIGNEN
RXMCOMMAALIGNEN
166
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defines the RX byte and word alignment ports.
Dir Clock Domain
Out RXUSRCLK2 This signal from the comma detection and realignment circuit is High
to indicate that the parallel data stream is properly aligned on byte
boundaries according to comma detection.
There are several cycles after RXBYTEISALIGNED is asserted before
aligned data is available at the FPGA RX interface.
RXBYTEISALIGNED responds to plus comma alignment when
RXPCOMMAALIGNEN is TRUE. RXBYTEISALIGNED responds
to minus comma alignment when RXMCOMMAALIGNEN is TRUE.
Some conditions when this signal could deviate from the expected
behavior are discussed in
Out RXUSRCLK2 This signal from the comma detection and realignment circuit indicates
that the byte alignment within the serial data stream has changed due to
comma detection.
Data can be lost or repeated when alignment occurs, which can cause
data errors (and disparity errors when the 8B/10B decoder is used).
Out RXUSRCLK2 This signal is asserted when the comma alignment block detects a
comma. The assertion occurs several cycles before the comma is
available at the FPGA RX interface.
In RXUSRCLK2 RXCOMMADETEN activates the comma detection and alignment
circuit.
Bypassing the comma and alignment circuit reduces RX datapath
latency.
In RXUSRCLK2 Aligns the byte boundary when comma plus is detected.
In RXUSRCLK2 Aligns the byte boundary when comma minus is detected.
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Description
0: Parallel data stream not aligned to byte boundaries
1: Parallel data stream aligned to byte boundaries
Alignment Status Signals, page
0: Byte alignment has not changed
1: Byte alignment has changed
0: Comma not detected
1: Comma detected
0: Bypass the circuit
1: Use the comma detection and alignment circuit
0: Disabled
1: Enabled.
0: Disabled
1: Enabled.
7 Series FPGAs GTP Transceivers User Guide
163.
UG482 (v1.9) December 19, 2016