Altera Arria V GZ Avalon-ST - Manual (Page 278)

Figure B-1: Using Lane Reversal to Solve PCB Routing Problems
The following figure illustrates a PCI Express card with ×4 IP Root Port and a ×4 Endpoint on the top side
of the PCB. Connecting the lanes without lane reversal creates routing problems. Using lane reversal
solves the problem.
0
1
2
3
Root Port
3
2
1
0
Endpoint
0
1
2
3
Root Port
0
1
2
3
Endpoint
No Lane Reversal
Results in PCB Routing Challenge
With Lane Reversal
Signals Route Easily
lane
reversal
no lane
reversal
B-2 Lane Initialization and Reversal
UG-01127_avst
2014.12.15
Altera Corporation Lane Initialization and Reversal
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