How to pass a global data type to an entity?

[Weng Tianxiang]

Hi,
I would like a help:
How to pass a global data type to an entity?

This is the statements I wrote and it has errors.

LIBRARY ieee;
USE ieee.std_logic_1164.all;
use ieee.numeric_std.all; -- for "unsigned"
LIBRARY unisim;
USE UNISIM.VCOMPONENTS.ALL;

package NewType is
type ByteType is array(7 downto 0) of std_logic_vector(7 downto 0);
end NewType;

entity AModule is port (
DataIn : ByteType;
...
);
end AModule;

architecture A of AModule is
....
end A;

What is wrong?

Thank you.

Weng

 

[Jonathan Bromley]

On 20 Sep 2005 08:35:13 -0700, "Weng Tianxiang" <wtx@umem.com> wrote:

This is the statements I wrote and it has errors.

LIBRARY ieee;
USE ieee.std_logic_1164.all;
use ieee.numeric_std.all; -- for "unsigned"
LIBRARY unisim;
USE UNISIM.VCOMPONENTS.ALL;

package NewType is
type ByteType is array(7 downto 0) of std_logic_vector(7 downto 0);
end NewType;

entity AModule is port (
DataIn : ByteType;
[...]

Two related problems:

(1)
LIBRARY and USE clauses do NOT apply to the whole source
file. They apply only to the next design unit.
Design unit = package, package body, entity, architecture,
configuration.
So, your LIBRARY and USE clauses apply only to the package.
You need to repeat them just before the entity.

(2)
Creating a package in a source file does NOT make the
package available to other design units in the source file.
So, you need to "USE" the package just before the entity
that needs it.

The solution....

LIBRARY ieee;
USE ieee.std_logic_1164.all; -- Only this is needed for NewType

package NewType is
type ByteType is array(7 downto 0) of std_logic_vector(7 downto 0);
end NewType;
--------------------------------------------------------------
LIBRARY ieee;
USE ieee.std_logic_1164.all;
use ieee.numeric_std.all;
LIBRARY unisim;
USE UNISIM.VCOMPONENTS.ALL;

USE work.NewType.all; -- needed to make "ByteType" visible

entity AModule is port (
DataIn : ByteType;

Note that it is now OK to put the two design units in two
separate source files. This is probably a good idea anyway.

HTH
--
Jonathan Bromley, Consultant

DOULOS - Developing Design Know-how
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[Mike Treseler]

Weng Tianxiang wrote:

How to pass a global data type to an entity?

Put your global package in a separate file.
Otherwise I have to compile AModule and
its parents just to use your byte type in myModule.

Use subtypes of standard vectors not new types.

Add:
use work.global_package.all;
at the top of AModule.


-- Mike Treseler
-----------------------------------------------------------------
-- File global_package.vhd
library ieee;
use ieee.std_logic_1164.all; -- for std_logic_vector

package global_package is
subtype byte_t is std_logic_vector(7 downto 0);
end package global_package;

-----------------------------------------------------------------
-- File AModule
library ieee;
use ieee.std_logic_1164.all; -- for std_logic_vector
use ieee.numeric_std.all; -- for unsigned
use work.global_package.all;

entity AModule is port (
DataIn : in byte_t;
DataOut : out unsigned(byte_t'range) -- make use of package
);
end entity AModule;

architecture synth of AModule is
begin
DataOut <= unsigned(DataIn); -- make use of unsigned
end architecture synth;
-----------------------------------------------------------------

 

[Weng Tianxiang]

Hi Mike, Jonathan,
I learn from your answers several times.

Thank you very much.

Weng