sramcontroller.vhd

SRAM_controller,资源多多共享,不亦乐乎!

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
---------------------------------------
entity sramcontroller is
port
(clock:in std_logic;
 datain:in std_logic_vector(7 downto 0);   		--------data that is prepare to write in SRAM
 memdatain:in std_logic_vector(7 downto 0);		--------data reading from SRAM
 memdataout:out std_logic_vector(7 downto 0);	--------data writing in SRAM
 dataout:out std_logic_vector(7 downto 0);
                                            	--------output data to appointed pin from SRAM
												--------in order to validate the exactitude of the program
 address:buffer integer range 0 to 2047;    	--------0->2^10   11-Bit address line
 ce:out std_logic;   							--------connect to CE#
 oe:out std_logic;								--------connect to OE#
 we:out std_logic								--------connect to WE#
);
end;
---------------------------------------------
architecture controller of sramcontroller is
signal counter:integer range 0 to 9;
signal read:std_logic;
begin
process(clock)
begin
if rising_edge(clock)then
 if counter=9 then 
   counter<=0;
 else
   counter<=counter+1;
 end if;
end if;
end process;
-------------------------------------------------
process(clock)
begin
if rising_edge(clock)then
 if counter=0 then
   ce<='1';
   if read='0'then
     memdataout<=datain;
   end if;
  elsif counter=1 then
    ce<='0';
  elsif counter=2 then
   if read='1'then
    dataout<=memdatain;
   end if;
  elsif counter=3 then
    ce<='1';
  elsif counter=4 then
    if address=2047 then					----------change to read mode if write as many as 2KB
      address<=0;
      read<='1';
    else
      address<=address+1;     				----------continue writing data to the next ROM cell
    end if;                                 ----------if it has not reach 2KB
   end if;
  end if;
end process;
oe<=not read;                               ----------read='0'(in writing mode if OE# voltage 
											----------is high,it shows that SRAM can't output data) 
---------------------------------------------------------------------------------------------------
we<=read;									----------read='0',(in writing mode,WE# voltage must be
											----------is low,or it show be in reading mode)
end;