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[/] [ttl_library/] [trunk/] [Testbench/] [Testbench_490.vhd] - Blame information for rev 3

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1 3 david237 
-----------------------------------------------------------------------
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-- Bipolar TTL models (VHDL)                                         --
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-- David R Brooks                                                    --
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-- June, 2016.  Perth, Australia                                     --
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-- Compliance: VHDL 2008                                             --
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-- Testbench for SN74LS490N: Dual decade counter                     --
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-----------------------------------------------------------------------
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library ieee;
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    use ieee.std_logic_1164.all;
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    use ieee.std_logic_misc.all;
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    use ieee.numeric_std.all;
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    use work.LSTTL.all;
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    use work.TTLPrivate.all;
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entity Testbench_490 is     -- Top-level bench
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generic(
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    StimClk  : std_logic      := '0';
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    CheckClk : std_logic      := '1';
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    Period   : time           := 120 ns;
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    Finish   : time           :=  20 us;
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    SevLevel : severity_level := failure
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);
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end entity;
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architecture Test of Testbench_490 is
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    signal RS, NRS, C0, C1 : std_logic;
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    signal CLK             : std_logic;
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    signal J,  B           : unsigned(1 downto 0);          -- Test stimuli
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    signal D,  E           : std_logic_vector(7 downto 0);  -- Expected & actual results
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    begin
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    RS <= not NRS;
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    -----------------------------------------------------------------------
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    -- Standard testbench components
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    -----------------------------------------------------------------------
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    TB: TTLBench
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    generic map(
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        StimClk  => StimClk,
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        CheckClk => CheckClk,
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        Period   => Period,
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        Finish   => Finish,
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        SevLevel => SevLevel
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    )
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    port map(
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        J    => J,
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        B    => B,
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        CLK  => CLK,
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        RS   => NRS,
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        D    => D,
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        E    => E
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    );
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    -----------------------------------------------------------------------
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    -- Generate expected results (with zero delays)
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    -----------------------------------------------------------------------
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    CA: process(B, RS) is
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        variable NA : natural;
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    begin
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        if    RS = '1' then
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            NA := 0;
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        elsif falling_edge(B(0)) then
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            case NA is
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                when 11 | 13 | 15 => NA := NA - 9;
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                when others       => NA := NA + 1;
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            end case;
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        end if;
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        D(3 downto 0) <= std_logic_vector(to_unsigned(NA, 4));
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    end process;
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    CB: process(B, RS) is
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        variable NB : natural;
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    begin
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        if    RS = '1' then
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            NB := 0;
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        elsif falling_edge(B(1)) then
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            case NB is
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                when 11 | 13 | 15 => NB := NB - 9;
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                when others       => NB := NB + 1;
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            end case;
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        end if;
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        D(7 downto 4) <= std_logic_vector(to_unsigned(NB, 4));
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    end process;
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    -----------------------------------------------------------------------
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    -- Device Under Test...
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    -----------------------------------------------------------------------
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    DUT: SN74LS490N
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    port map(
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    X_1  => B(0),  -- CPA\
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    X_2  => RS,    -- MRA
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    X_3  => E(0),  -- Q0A
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    X_4  => '0',   -- MSA
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    X_5  => E(1),  -- Q1A
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    X_6  => E(2),  -- Q2A
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    X_7  => E(3),  -- Q3A
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    X_8  => open,  -- GND
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    X_9  => E(7),  -- Q3B
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    X_10 => E(6),  -- Q2B
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    X_11 => E(5),  -- Q1B
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    X_12 => '0',   -- MSB
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    X_13 => E(4),  -- Q0B
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    X_14 => RS,    -- MRB
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    X_15 => B(1),  -- CPB\
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    X_16 => open   -- Vcc
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);
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end architecture Test;

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