Does anybody know how can I disable the automatic optimizer in Quartus II to prevent it from eliminating redundant gates ? (I am trying to implement a delay line using a cascade of inverters, which Quartus removes during compilation since they are logically redundant.) thanks,
Quartus II - Disabling the Optimizer to use gate delay
Started by ●June 17, 2004
Reply by ●June 17, 20042004-06-17
vbishtei@hotmail.com (vadim) wrote in message news:<2a613f5d.0406170517.611ae93c@posting.google.com>...> Does anybody know how can I disable the automatic optimizer in Quartus II > to prevent it from eliminating redundant gates ? > > (I am trying to implement a delay line using a cascade of inverters, which > Quartus removes during compilation since they are logically redundant.) > > thanks,Hi Vadim, Building delay chains is not recommended. You can use LCELL buffer as shown below to force a route through two lcells. module test (in,out); input in; output out; wire lcaout; lcell lca (in,lcaout); lcell lcb (lcaout,out); endmodule Hope this helps. Subroto Datta Altera Corp.
Reply by ●June 17, 20042004-06-17
Hello Vadim, In VHDL, enter the following: signal delay_gate : std_logic; attribute keep : boolean; attribute keep of lval_rowdel_delaln : signal is true; Similar construct exists for Verilog. This turns delay_gate into an LCELL of whatever is feeding it. Quartus doesn't remove LCELLs, unless Remove Redundant Logic Cells is set in your design, which by default it is off - check your .qsf or under Assignments/Settings/Analysis&Synth/More Settings. If you want to keep a redundant register, set REMOVE_DUPLICATE_REGISTERS to OFF for that register. HTH, -- Pete vbishtei@hotmail.com (vadim) wrote in message news:<2a613f5d.0406170517.611ae93c@posting.google.com>...> Does anybody know how can I disable the automatic optimizer in Quartus II > to prevent it from eliminating redundant gates ? > > (I am trying to implement a delay line using a cascade of inverters, which > Quartus removes during compilation since they are logically redundant.) > > thanks,
Reply by ●June 17, 20042004-06-17
Oops cut and paste error ... my other msg should read: attribute keep of delay_gate : signal is true; -- Pete vbishtei@hotmail.com (vadim) wrote in message news:<2a613f5d.0406170517.611ae93c@posting.google.com>...> Does anybody know how can I disable the automatic optimizer in Quartus II > to prevent it from eliminating redundant gates ? > > (I am trying to implement a delay line using a cascade of inverters, which > Quartus removes during compilation since they are logically redundant.) > > thanks,