Subversion Repositories epc_rfid_transponder

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--     Politecnico di Torino                                              

--     Dipartimento di Automatica e Informatica             

-------------------------------------------------------------------------------

-------------------------------------------------------------------------------     

--

--     Title          : Flash Memory USR

--

--     File name      : flashmemUSR.vhd 

--

--     Description    : Flash memory model.  

--

--     Author         : Paolo Bernardi <paolo.bernardi@polito.it>

--                                              Erwing R. Sanchez <erwing.sanchez@polito.it>

--

--     Rev. History   : E.R. Sanchez

--                              - Ready/busy input removed because not used

--                              - "Bits" generic removed

--                              - RP input removed

--                              - Command codes changed to work with Data = 16

--                      E.R. Sanchez 

--                              - Include Parameters & Initialization

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library IEEE;

use IEEE.STD_LOGIC_1164.all;

use IEEE.STD_LOGIC_ARITH.all;

use IEEE.STD_LOGIC_UNSIGNED.all;

use IEEE.std_logic_textio.all;

use STD.TEXTIO.all;

entity Flash_MeM_USR is

  generic (

    Words : integer := 256;           -- number of addresses

    Addr  : integer := 5;  -- number of pins reserved for addresses

    Data  : integer := 16

    );

  port (

    A  : in  std_logic_vector(Addr-1 downto 0);  -- Address inputs

    D  : in  std_logic_vector(Data-1 downto 0);  -- Data input

    Q  : out std_logic_vector(Data-1 downto 0);  -- Data output

    G  : in  std_logic;                 -- Output enable

    W  : in  std_logic;                 -- Write  enable

    RC : in  std_logic;                 -- Row/Column address select

    st : out std_logic                  -- Interface reset

    );

end Flash_MeM_USR;

--synopsys synthesis_on

architecture Behavioural of Flash_MeM_USR is

--synopsys synthesis_off

  type   Flash_Type is array (0 to Words-1) of std_logic_vector(Data-1 downto 0);

  signal Mem : Flash_Type := (others => (others => '1'));

  signal Addr_int : std_logic_vector((2*Addr)-1 downto 0);

  signal Data_int : std_logic_vector(Data-1 downto 0);

  signal program         : std_logic := '0';

  signal erase           : std_logic := '0';

  signal i               : natural range Words-1 downto 0;

  signal status_register : std_logic_vector(Data-1 downto 0);

  signal status          : std_logic;

  signal InitIsDoneFlag  : std_logic := '0';

  function resetVector (dim : natural) return std_logic_vector is

    variable vectorOut : std_logic_vector(dim -1 downto 0);

    variable i         : natural range dim downto 0;

  begin

    for i in 0 to dim-1 loop

      vectorOut(i) := '0';

    end loop;

    return vectorOut;

  end resetVector;

  function erase_mem (mem : Flash_Type) return Flash_Type is

    variable mem_out : Flash_Type;

    variable i       : natural range Words-1 downto 0;

  begin

    for i in 0 to Words-1 loop

      Mem_out(i) := (others => '1');    --"11111111";

    end loop;

    return mem_out;

  end erase_mem;

  --synopsys synthesis_on

begin  --BEHAVIOURAL

  --synopsys synthesis_off

  write_first : process (RC)

  begin

    if RC'event and RC = '0' then

      Addr_int(Addr-1 downto 0) <= A;

    end if;

  end process write_first;

  write_second : process (RC)

  begin

    if RC'event and RC = '1' then

      Addr_int((2*Addr)-1 downto Addr) <= A;

    end if;

  end process write_second;

  w_data : process (W)

  begin

    if W'event and W = '1' then

      if program = '1' then

        Mem(conv_integer(unsigned(Addr_int))) <= D after 50 ns;

        status_register                       <= conv_std_logic_vector(64, Data);  --"01000000"

        Data_int                              <= resetVector(Data_int'length);

        st                                    <= '0';

      elsif erase = '1' then

        Mem      <= erase_mem(Mem) after 750000000 ns;

        Data_int <= resetVector(Data_int'length);

        st       <= '1'            after 750000000 ns;

      else

        Data_int        <= D;

        status_register <= (others => '0');  --"00000000";

        st              <= '0';

      end if;

    end if;

  end process w_data;

  read_data : process (G)

  begin

    if G'event and G = '0' then

      if status = '0' then

        Q <= Mem(conv_integer(unsigned(Addr_int))) after 50 ns;

      else

        Q <= status_register after 750000000 ns;

      end if;

    elsif G'event and G = '1' then

      Q <= (others => 'U') after 50 ns;  -- "UUUUUUUU"

    end if;

  end process read_data;

  decode : process (Data_int)

  begin

    case conv_integer(Data_int) is

      when 64 =>                        -- "01000000"  program

        program <= '1';

        erase   <= '0';

        status  <= '0';

      when 32 =>                        -- "00100000"  erase

        program <= '0';

        erase   <= '1';

        status  <= '0';

      when 112 =>                       -- "01110000"  read status reg

        program <= '0';

        erase   <= '0';

        status  <= '1';

      when others =>

        program <= '0';

        erase   <= '0';

        status  <= '0';

    end case;

  end process decode;

--  -- purpose: Load Memory from file  

--  load_memory : process(A, D, G, W, RC, InitIsDoneFlag)

--    file init_mem_file       : text open read_mode is "meminit.txt";

--    variable inline, outline : line;

--    variable add             : natural;

--    variable c               : character;

--    variable Mem_var         : Flash_Type;

--  begin  -- process load_memory

--    if InitIsDoneFlag = '0' then

--      -- Clear Memory

--      for i in 0 to Words-1 loop

--        Mem_var(i) := (others => '0');

--      end loop;  -- i

--      -- Load

--      while not endfile(init_mem_file) loop

--        readline(init_mem_file, inline);

--        read(inline, add);

--        read(inline, c);

--        if c /= ':' then

--          write(outline, string'("Syntax Error"));

--          writeline(output, outline);

--          assert false report "Mem Loader Aborted" severity failure;

--        end if;

--        for i in (Data-1) downto 0 loop

--          read(inline, c);

--          if c = '1' then

--            Mem_var(add)(i) := '1';

--          elsif c = '0' then

--            Mem_var(add)(i) := '0';

--          else

--            write(outline, string'("Invalid Character-Set to '0'"));

--            writeline(output, outline);

--            Mem_var(add)(i) := '0';

--          end if;

--        end loop;  -- i

--      end loop;

--      Mem <= Mem_var;

--      InitIsDoneFlag <= '1';

--    end if;

--  end process load_memory;

--synopsys synthesis_on

end Behavioural;

--synopsys synthesis_off

configuration CFG_Flash_MeM_USR of Flash_MeM_USR is

  for Behavioural

  end for;

end CFG_Flash_MeM_USR;

--synopsys synthesis_on