buffer port

Discussion in 'VHDL' started by Max, Sep 22, 2003.

  1. Max

    Max Guest

    I have this files:

    ------ main.vhd---------------
    entity main is
    Port ( sig : buffer std_logic);
    end main;

    architecture Behavioral of main is

    component a is
    Port ( siga : in std_logic);
    end component;
    component b is
    Port ( sigb : out std_logic);
    end component;

    begin
    aa: component a
    Port map( siga => sig);
    bb: component b
    Port map ( sigb => sig); -- here is the error
    end Behavioral;
    --
    ----------- a.vhd --------------------
    entity a is
    Port ( siga : in std_logic);
    end a;
    architecture Behavioral of a is
    begin

    end Behavioral;
    --
    ----------- b.vhd --------------------
    entity b is
    Port ( sigb : out std_logic);
    end b;
    architecture Behavioral of b is
    begin
    sigb <= '1';
    end Behavioral;
    --

    I obtain the following error in synthesis:
    ERROR:HDLParsers:1411 - main.vhd Line XX. Parameter sig of mode buffer
    can not be associated with a formal port of mode out.

    Buffer port is the same of out port, but can be read from within the
    entity, isn't it?
    So why occurs this error.

    thanks
     
    Max, Sep 22, 2003
    #1
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  2. Max,

    You will find your answer in the faq
    http://www.vhdl.org/vi/comp.lang.vhdl/FAQ1.html#buffer_ports

    Egbert Molenkamp


    "Max" <> schreef in bericht
    news:...
    > I have this files:
    >
    > ------ main.vhd---------------
    > entity main is
    > Port ( sig : buffer std_logic);
    > end main;
    >
    > architecture Behavioral of main is
    >
    > component a is
    > Port ( siga : in std_logic);
    > end component;
    > component b is
    > Port ( sigb : out std_logic);
    > end component;
    >
    > begin
    > aa: component a
    > Port map( siga => sig);
    > bb: component b
    > Port map ( sigb => sig); -- here is the error
    > end Behavioral;
    > --
    > ----------- a.vhd --------------------
    > entity a is
    > Port ( siga : in std_logic);
    > end a;
    > architecture Behavioral of a is
    > begin
    >
    > end Behavioral;
    > --
    > ----------- b.vhd --------------------
    > entity b is
    > Port ( sigb : out std_logic);
    > end b;
    > architecture Behavioral of b is
    > begin
    > sigb <= '1';
    > end Behavioral;
    > --
    >
    > I obtain the following error in synthesis:
    > ERROR:HDLParsers:1411 - main.vhd Line XX. Parameter sig of mode buffer
    > can not be associated with a formal port of mode out.
    >
    > Buffer port is the same of out port, but can be read from within the
    > entity, isn't it?
    > So why occurs this error.
    >
    > thanks
     
    Egbert Molenkamp, Sep 22, 2003
    #2
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