Disconnect Example - EDA Playground
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library IEEE;
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use IEEE.std_logic_1164.all;
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​
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entity testbench is
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end entity testbench;
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​
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architecture DUMMY of testbench is
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begin
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  DUT : entity work.EX_DISCONNECT(A1);
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end architecture DUMMY;
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-- THE EXAMPLES ARE DIRECTLY BELOW
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                                               library IEEE;
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                                               use IEEE.STD_LOGIC_1164.all;
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                                               entity EX_DISCONNECT is
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                                               end entity EX_DISCONNECT;
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----------------------------------------
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architecture A1 of EX_DISCONNECT is
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​
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  signal Foo : STD_LOGIC bus;
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  disconnect Foo: STD_LOGIC after 10 NS; -- then goes to 'Z'
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  signal D : STD_LOGIC;
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begin
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​
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  Logic: block (D) is -- block executes while D = '1'
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  begin
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    Foo <= guarded D; -- Foo remains '1' for up to 10 NS after D /= '1' then goes to 'Z'
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  end block Logic;
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----------------------------------------
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                                                 Stim: process
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                                                 begin
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                                                   D <= '0';
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                                                wait for 20 NS;
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                                                   D <= '1';
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                                                wait for 20 NS;
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                                                D <= '0';
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                                                wait for 15 NS;
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                                                   D <= '1';
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                                                wait for 5 NS;
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                                                D <= '0';
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                                                   wait for 15 NS;
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                                                   wait;
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                                                 end process Stim;
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                                               end architecture A1;
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# Disconnect Example
A disconnect defines the delay with which the drivers of a guarded signal are disconnected from the resolution function, when the signal is assigned by a guarded signal assignment. A driver is disconnected by assigning the signal the value null.
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## Notes
 * The list of signal names may be replaced by others or all.
 * Each signal must be declared as a guarded signal, and must be assigned in a guarded signal assignment.
 * Not synthesizable. Instead, use the types STD_LOGIC and STD_LOGIC_VECTOR, and assign the value 'Z' to a signal to represent high impedance.
 
**Don't use guarded signals or disconnection!**

Disconnect Example

A disconnect defines the delay with which the drivers of a guarded signal are disconnected from the resolution function, when the signal is assigned by a guarded signal assignment. A driver is disconnected by assigning the signal the value null.

Notes

  • The list of signal names may be replaced by others or all.
  • Each signal must be declared as a guarded signal, and must be assigned in a guarded signal assignment.
  • Not synthesizable. Instead, use the types STD_LOGIC and STD_LOGIC_VECTOR, and assign the value 'Z' to a signal to represent high impedance.

Don't use guarded signals or disconnection!

91010:0