1–8
Chapter 1: Cyclone IV Transceivers Architecture
Transmitter Channel Datapath
February 2015
Altera Corporation
at time
n
+ 2 is encoded as a positive disparity code group. In the same example, the
current running disparity at time
n
+ 5 indicates that the K28.5 in time
n
+ 6 should be
encoded with a positive disparity. Because
tx_forcedisp
is high at time
n
+ 6, and
tx_dispval
is high, the K28.5 at time
n
+ 6 is encoded as a negative disparity code
group.
Miscellaneous Transmitter PCS Features
The transmitter PCS supports the following additional features:
■
Polarity inversion—corrects accidentally swapped positive and negative signals
from the serial differential link during board layout by inverting the polarity of
each bit. An optional
tx_invpolarity
port is available to dynamically invert the
polarity of every bit of the 8-bit or 10-bit input data to the serializer in the
transmitter datapath.
shows the transmitter polarity inversion feature.
1
tx_invpolarity
is a dynamic signal and might cause initial disparity errors
at the receiver of an 8B/10B encoded link. The downstream system must be
able to tolerate these disparity errors.
Figure 1–9. Transmitter Polarity Inversion
Con
v
erted data output to the
transmitter serializer
Output from transmitter PCS
0
1
1
1
0
0
1
0
0
0
MSB
tx_in
v
polarity = HIGH
LSB
1
0
0
0
1
1
0
1
1
1
MSB
LSB
Summary of Contents for Cyclone IV
Page 10: ...x Chapter Revision Dates Cyclone IV Device Handbook March 2016 Altera Corporation Volume 1...
Page 14: ...I 2 Section I Device Core Cyclone IV Device Handbook March 2016 Altera Corporation Volume 1...
Page 274: ...vi Contents Cyclone IV Device Handbook February 2015 Altera Corporation Volume 2...
Page 440: ...iv Contents Cyclone IV Device Handbook December 2016 Altera Corporation Volume 3...
Page 442: ...vi Chapter Revision Dates Cyclone IV Device Handbook December 2016 Altera Corporation Volume 3...
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