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AR# 58562

MIG 7 Series RLDRAM3 - tWTR counter logic causes controller to lock up


Version Found: v2.0 Rev1
Version Resolved: See (Xilinx Answer 54025)

In some cases, when performing a Write command followed by a Read command, the "twtr_ok" signal inside *_rld_mc.v deasserts and always remains Low. This causes the memory controller to lock up, preventing any commands from being sent to the DRAM.


This is a RTL bug found in the initialization logic of "twtr_cnt" inside the *_rld_mc.v module.

To work around the issue, the following RTL changes can be made inside *_rld_mc.v:

always @ (posedge clk)
      if (rst_clk) begin
         twtr_cnt[0] <= #TCQ RLD_TWTR; 
         twtr_cnt[1] <= #TCQ RLD_TWTR; 
         prev_wr_pointer_twtr <= #TCQ 'h0;
      // when 4 write requests are issued in a user clock cycle

Revision History
12/18/2013 - Initial release

AR# 58562
Date Created 11/26/2013
Last Updated 12/06/2013
Status Active
Type Known Issues
  • Kintex-7
  • Virtex-7
  • MIG 7 Series