
The following table defines the RX buffer attributes.
Table 65: RX Buffer Attributes
Attribute
Type
Description
CH[0/1]_RX_PCS_CFG0
16-bit Binary
Reserved. Use the recommended value from the
Wizard.
CH[0/1]_RXFIFO_UNDERFLOW
1-bit Binary
A value of 1 indicates FIFO underflow.
For channel 0, bit[8] of DRP Address
0x48B
.
For channel 1, bit[8] of DRP Address
0x68B
.
Note
:
This is a read-only attribute.
CH[0/1]_RXFIFO_OVERFLOW
1-bit Binary
A value of 1 indicates FIFO overflow.
For channel 0, bit[9] of DRP Address
0x48B
.
For channel 1, bit[9] of DRP Address
0x68B
.
Note
:
This is a read-only attribute.
RX FEC
The Integrated KP4 Reed-Solomon Forward Error Correction (RS-FEC) provides a robust multi-bit
error detection/correction algorithm that protects up to 2 x 58 Gb/s or 1x116 Gb/s electrical and
optical links. This section describes the operation of the Integrated KP4 RS-FEC within the
Ult™ device GTM transceivers.
KP4 FEC is based on the RS(544,514) code, which encodes message blocks of 5140 bits to
produce codewords of 5440 bits. For a detailed description of the RS-FEC sublayer in Ethernet,
including the definition of the KP4 FEC code, refer to clause 91 of the IEEE Standard for Ethernet
(IEEE Std 802.3-2015). The same FEC code is used in other standards such as OTN FlexO and
Interlaken.
The Integrated KP4 RS-FEC for each GTM dual is composed of two logical slices for each
channel. These can operate as two independent RS-FEC processing units at up to 58 Gb/s each,
or as one unified unit at up to 116 Gb/s. When operating at up to 116 Gb/s, data is transmitted
and received over four virtual FEC lanes as described in IEEE 802.3-2015 clause 91. When
operating as 2 x 58 Gb/s, data can be transmitted and received over two virtual FEC lanes per
58 Gb/s channel, or as a raw data stream (one virtual lane) with optional PN scrambling for
backplane operations. The general principle of operation of the FEC is the same whichever mode
is chosen.
Chapter 4: Receiver
UG581 (v1.0) January 4, 2019
Virtex Ult GTM Transceivers
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