Auto Link Recovery for Simplex - 12.0 English

PG074 Aurora 64B/66B LogiCORE IP Product Guide

Document ID
PG074
Release Date
2022-10-19
Version
12.0 English

The simplex Aurora 64b/66b core must follow a predefined reset sequence for the simplex cores to link up and work as expected. The simplex TX core needs to be in reset or should keep sending initialization sequences until the RX side is up. As part of RX link recovery, polarity inversion and other IP specific checks are to re-negotiate the link. If a change in polarity occurs during runtime, the core requires a complete reset sequence to recover.

The simplex auto link recovery feature in the core eliminates this requirement, thereby removing any reset sequence requirement between simplex TX and simplex RX cores.

Auto Link Recovery in Aurora 64b/66b simplex designs is based on the reception of Channel Bonding (CB) patterns. Reception of the pattern allows the RX simplex core to come up independently of the TX Simplex core bring-up. The parameter PERIODIC_CB_COUNT denotes in user_clk cycles the time from the start of one periodic CB pattern to the start of the next successive CB pattern. The minimum value is 6,080. The maximum value is 163,839. The periodic CB pattern includes transmission of CB-IDLE patterns with the appropriate spacing to help the receiver achieve channel up even if the link was down for some reason. Typically, these CB-IDLE patterns take up to 600 user-clk cycles. Spacing of these patterns are chosen to match the throughput of the earlier released core versions which were transmitting a Single CB character periodically.

Bandwidth occupancy = Number of user_clk cycles required by CB pattern/ Total number of user_clk cycles)*100.

You can increase the count based on the following formula:

PERIODIC_CB_COUNT = Minimum {1048570, INTEGER part of [{16777215*INIT_CLK_PERIOD}/{4*USER_CLK_PERIOD}]}

where,

INIT_CLK_PERIOD is init_clk time-period in ns

USER_CLK_PERIOD is user_clk time-period in ns.

IMPORTANT: Xilinx highly recommends that the maximum value be fixed at 163,839 and a change in the value should be performed with careful analysis and testing.