Enabling 64B/66B Mode; Rx 8B/10B Block; Functional Description; Ports And Attributes - Xilinx Virtex-6 FPGA User Manual

Chapter 4: Receiver

Enabling 64B/66B Mode

Follow these steps to enable the 64B/66B mode in the GTH receiver:
1.
2.
3.
4.

RX 8B/10B Block

Functional Description

The GTH transceiver includes an 8B/10B decoder to decode RX data without consuming
FPGA resources. The decoder includes status signals to indicate errors and incoming
control sequences.
Serial data must be aligned to symbol boundaries before it can be used as parallel data. To
make alignment possible, transmitters send a recognizable sequence, usually called a
comma. The receiver searches for the comma in the incoming data. When it finds a comma,
the receiver moves the comma to a byte boundary so the received parallel words match the
transmitted parallel words. The receiver's 8B/10B block includes an alignment block that
detects the following commas: K28.1, K.28.5, and K28.7.

Ports and Attributes

Table 4-17
.
Table 4-17: RX 8B/10B Block Ports
Port
RXCODEERR0[7:0]
RXCODEERR1[7:0]
RXCODEERR2[7:0]
RXCODEERR3[7:0]
126
Set PCS_MODE_LANE<n>[7:4] to 4'b0001.
Set PCS_RESET_LANE<n> to 0xF3FE.
Set PCS_RESET_1_LANE<n>[1:0] to 2'b10.
Set RX_FABRIC_WIDTH<n> to "6466."
defines RX 8B/10B block ports.
Dir Clock Domain
Out RXUSERCLKIN0
RXUSERCLKIN1
RXUSERCLKIN2
RXUSERCLKIN3
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Description
These outputs indicate an error occurred on RXDATA<n> or they
are used as an extension of RXDATA<n> depending on the mode
selected in the receive datapath:
8B/10B: These outputs indicate that RXDATA<n> is the result of
an 8B/10B code error.
RXCODEERR<n>[7] corresponds to RXDATA<n>[63:56]
RXCODEERR<n>[6] corresponds to RXDATA<n>[55:48]
RXCODEERR<n>[5] corresponds to RXDATA<n>[47:40]
RXCODEERR<n>[4] corresponds to RXDATA<n>[39:32]
RXCODEERR<n>[3] corresponds to RXDATA<n>[31:24]
RXCODEERR<n>[2] corresponds to RXDATA<n>[23:16]
RXCODEERR<n>[1] corresponds to RXDATA<n>[15:8]
RXCODEERR<n>[0] corresponds to RXDATA<n>[7:0]
64B/66B: RXCODEERR<n>[0] indicates a 64B/66B code error.
RXCODEERR<n>[7:1] are not used for this mode.
Raw mode: These outputs are used as part of RXDATA<n>[79:72].
Virtex-6 FPGA GTH Transceivers User Guide
UG371 (v2.0) February 16, 2010