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Rom Interface

This document describes a VHDL entity for a ROM interface. The entity has ports for a clock, reset, enable signals, and data inputs and outputs. The architecture contains a state machine with 5 states that controls the bus selection, wait signal, and data output based on the clock, reset and other input signals.

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Roshini M S
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33 views2 pages

Rom Interface

This document describes a VHDL entity for a ROM interface. The entity has ports for a clock, reset, enable signals, and data inputs and outputs. The architecture contains a state machine with 5 states that controls the bus selection, wait signal, and data output based on the clock, reset and other input signals.

Uploaded by

Roshini M S
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as TXT, PDF, TXT or read online on Scribd
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library ieee ;

use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.std_logic_arith.all;

entity my_rom_interface is
port (
rst_rom : in std_logic;
clk_rom : in std_logic;
rom_en_int : in std_logic;

im_reqn : in std_logic;

rom_data_in : in std_logic_vector(31 downto 0);

wait_processor : out std_logic;


bus_sel : out std_logic;
dd_ins_data : out std_logic_vector(31 downto 0)

);

end my_rom_interface ;

architecture my_rom_interface_a of my_rom_interface is

type state_type is (S0,S1,S2,S3,S4);

signal state_rom : state_type;

signal bus_sel_o : std_logic;

begin

bus_sel <= bus_sel_o after 10 ns;


--
--bus_sel <= bus_sel_o;

rom_p : process (clk_rom,rst_rom,state_rom)


begin

if clk_rom'event and clk_rom = '1' then

if rst_rom = '0' then

wait_processor <= '1';


bus_sel_o <= '0';
state_rom <= S0;
dd_ins_data <= (others => '0');

else
case state_rom is

when S0 =>
if rom_en_int = '1' then

wait_processor <= '0';


bus_sel_o <= '1';

state_rom <= S1;

end if;

when S1 =>

state_rom <= S2;

when S2 =>

bus_sel_o <= '0';


dd_ins_data <= rom_data_in;

if im_reqn = '0' then


state_rom <= S3; -- ins memory
access
else
state_rom <= S0;
wait_processor <= '1';

end if;

when S3 =>

state_rom <= S4;

when S4 =>

wait_processor <= '1';


state_rom <= S0;

when others =>


null;

end case;

end if;
end if;
end process rom_p;

end my_rom_interface_a;

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