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AR# 63110

Design Advisory for 7 Series GTH Transceiver Wizard: DFE incorrectly set to HOLD after adaptation in Vivado 2013.4 to 2014.4

Description

(UG476)  The 7 Series GTX/GTH Transceivers User Guide recommends GTH DFE to be used in fully auto adaptive mode. 

Starting from the 7 Series GTH Transceiver Wizard v3.1 in Vivado 2013.4 until v3.4 Rev1 in Vivado 2014.4, this is incorrectly set to hold for a GTH transceiver after convergence.

This should not be held or frozen after convergence but instead left in auto adapt mode (RXDFEAGCHOLD = 1'b0, RXDFELFHOLD = 1'b0). 

This is only applicable to the specified wizard versions in Vivado and not ISE.

Solution

This is fixed in the next version of the wizard in Vivado 2015.1, but the following can be used as a work-around:
 
Change the below code in <component_name>_rx_startup_fsm.v:
 

if(time_out_adapt)
            begin
               if(EQ_MODE == "DFE")
               begin
                  RXDFEAGCHOLD  <= `DLY 1'b1;
                  RXDFELFHOLD   <= `DLY 1'b1;
               end
               else
               begin
                  RXDFEAGCHOLD  <= `DLY 1'b0;
                  RXDFELFHOLD   <= `DLY 1'b0;
                  RXLPMHFHOLD   <= `DLY 1'b0;
                  RXLPMLFHOLD   <= `DLY 1'b0;
               end
            end  


To 
 

if(time_out_adapt)
            begin
               if(EQ_MODE == "DFE")
               begin
                  RXDFEAGCHOLD  <= `DLY 1'b0;
                  RXDFELFHOLD   <= `DLY 1'b0;
               end
               else
               begin
                  RXDFEAGCHOLD  <= `DLY 1'b0;
                  RXDFELFHOLD   <= `DLY 1'b0;
                  RXLPMHFHOLD   <= `DLY 1'b0;
                  RXLPMLFHOLD   <= `DLY 1'b0;
               end
            end  

 
 
Revision History:
01/13/2015 - Initial Release  
AR# 63110
Date Created 12/11/2014
Last Updated 05/12/2015
Status Active
Type Design Advisory
Devices
  • Virtex-7
IP
  • 7 Series FPGAs Transceivers Wizard