Setting The Tx Driver; Amplitude (Swing); Post-Cursor Emphasis - Xilinx Virtex-6 FPGA User Manual

Chapter 3: Transmitter
Table 3-15: TX Configurable Driver Attributes (Cont'd)
Notes:
1. The hexadecimal values for TX_CFG0_LANE<n> assume that the defaults for the other bits in the

Setting the TX Driver

The TX amplitude and swing controls are set via attributes using the DRP or the
Management interface.

Amplitude (Swing)

The override bit has to be set as specified:
•
•
•

Post-Cursor Emphasis

The override bit has to be set as specified:
•
•
100
Attribute
TX_CFG1_LANE0
TX_CFG1_LANE1
TX_CFG1_LANE2
TX_CFG1_LANE3
TX_PREEMPH_LANE0
TX_PREEMPH_LANE1
TX_PREEMPH_LANE2
TX_PREEMPH_LANE3
register are used and that the channel is powered up and not in reset.
TX_CFG1_LANE<n>[9] = tx_swing_ovrrd_en = 1'b1
TX_CFG0_LANE<n>[6:3] = tx_swing (see
settings)
TX_CFG0_LANE<n>[2:0] = tx_ibias (see
TX_CFG1_LANE<n>[8] = tx_premptap_ovrrd_en = 1'b1
TX_PREEMPH_LANE<n>[7:4] = tx_postcursor
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Type
16-bit Binary This attribute enables the differential voltage
swing and the pre-cursor and post-cursor
transmit emphasis.
[15:10]: Reserved. Tie these inputs to
6'b000011.
[9]: This bit gives control to tx_swing in the
TX_CFG0_LANE<n> registers for voltage
swing control (tx_swing_ovrrd_en). Set this bit
to 1'b1.
[8]: This bit gives control to tx_postcursor and
tx_precursor in the TX_PREEMPH_LANE<n>
attribute for transmit post-cursor and
pre-cursor emphasis (tx_premptap_ovrrd_en).
Set this bit to 1'b1.
[7:0]: Reserved. Tie these inputs to 8'h00.
16-bit Binary This attribute controls the pre-cursor and
post-cursor transmit emphasis. For pre-emphasis
and post-emphasis settings, see
Driver.
[15:8]: Reserved. Tie these inputs to 8'hA0.
[7:4]: Pre-emphasis settings for the first
post-cursor (tx_postcursor).
[3:0]: Pre-emphasis settings for the pre-cursor
or the second post-cursor (tx_precursor).
Table 3-15
Table 3-15
Virtex-6 FPGA GTH Transceivers User Guide
Description
Setting the TX
for voltage swing control
for voltage swing control settings)
UG371 (v2.0) February 16, 2010