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10–14
Chapter 10: Transceiver Reconfiguration Controller
DFE
Altera Transceiver PHY IP Core
March 2012
Altera Corporation
User Guide
Table 10–12
describes the EyeQ registers that you can access.
1
All undefined register bits are reserved and must be set to 0.
Refer to
“Changing Transceiver Settings Using Register-Based Reconfiguration” on
page 10–27
for the procedures you can use to control the Eye Monitor.
DFE
The DFE is an infinite impulse response filter (non-linear) that compensates for
inter-symbol interference (ISI). Because the values of symbols previously detected are
known, the DFE engine can estimate the ISI contributed by these symbols and cancel
out this ISI by subtracting the predicted value from subsequent symbols. This
mechanism allows DFE to boost the signal to noise ratio of the received data. You can
use DFE in conjunction with the receiver's linear equalization and with the
transmitter's pre-emphasis feature.
If you enable the DFE engine, you can determine the optimal settings by monitoring
the BER of the received data at each setting and specify the DFE settings that yield the
widest eye.
Table 10–13
lists the direct DFE registers that you can access using Avalon-MM reads
and writes on reconfiguration management interface.
1
All undefined register bits are reserved.
Table 10–12. EyeQ Offsets and Values
Offset
Bits
R/W
Register Name
Description
0x0
[1]
RW
Control
Writing a 1 to this bit enables the Eye monitor.
0x1
[5:0]
RW
Horizontal phase
Taken together, the
horizontal phase
and
vertical height
specify the Cartesian x-y
coordinates of the point on the eye diagram that
you want to sample. You can increment through
64 phases over 2 UI on the horizontal axis.
0x2
[5:0]
RW
Vertical height
Taken together, the
horizontal phase
and
vertical height
specify the Cartesian x-y
coordinates of the point on the eye diagram that
you want to sample. You can specify 64 heights
over 2 UI on the vertical axis.
Table 10–13. DFE Registers (Part 1 of 2)
Recon
-fig
Addr
Bits
R/W
Register Name
Description
7’h18
[9:0]
RW
logical channel address
The logical channel address. Must be specified when
performing dynamic updates. The Transceiver
Reconfiguration Controller maps the logical address to the
physical address.