Subversion Repositories epc_rfid_transponder

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--     Politecnico di Torino                                              

--     Dipartimento di Automatica e Informatica             

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--

--     Title          : EPC Class1 Gen2 RFID Tag - Inventoried and Selected Flags Controller

--

--     File name      : InvSelFlagsCtrl.vhd 

--

--     Description    : Inventoried and Selected flag controller. It provides a

--                      suitable interface with the flag model and deals with

--                      refreshing procedures.

--                      

--     Authors        : Erwing R. Sanchez <erwing.sanchezsanchez@polito.it>

--

--     Rev. History   : 29 June 06 

--                                 

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library IEEE;

use IEEE.STD_LOGIC_1164.all;

use IEEE.std_logic_unsigned.all;

entity InvSelFlagCtrl is

  generic (

    REFRESHING_CLK_CYC     : integer := 255);  -- Number of clock cycles to refresh flags

  port (

    clk   : in  std_logic;

    rst_n : in  std_logic;

    S0in  : in  std_logic;

    S1in  : in  std_logic;

    S2in  : in  std_logic;

    S3in  : in  std_logic;

    SLin  : in  std_logic;

    S0en  : in  std_logic;

    S1en  : in  std_logic;

    S2en  : in  std_logic;

    S3en  : in  std_logic;

    SLen  : in  std_logic;

    S0out : out std_logic;

    S1out : out std_logic;

    S2out : out std_logic;

    S3out : out std_logic;

    SLout : out std_logic);

end InvSelFlagCtrl;

architecture FlagController1 of InvSelFlagCtrl is

  component InvSelFlag

    port (

      S1i : in  std_logic;

      S2i : in  std_logic;

      S3i : in  std_logic;

      SLi : in  std_logic;

      S1o : out std_logic;

      S2o : out std_logic;

      S3o : out std_logic;

      SLo : out std_logic);

  end component;

-- synopsys synthesis_off

  signal S0out_i, S1out_i, S2out_i, S3out_i, SLout_i : std_logic;

  signal S1i, S2i, S3i, SLi                          : std_logic;

  signal S1o, S2o, S3o, SLo                          : std_logic;

  signal RefCnt                                      : integer;

-- synopsys synthesis_on  

begin  -- FlagController1

-- synopsys synthesis_off

  -- OUTPUT WIRES

  S0out <= S0out_i;

  S1out <= S1out_i;

  S2out <= S2out_i;

  S3out <= S3out_i;

  SLout <= SLout_i;

  REGISTERS : process (clk, rst_n)

  begin  -- process REGISTERS

    if rst_n = '0' then                 -- asynchronous reset (active low)

      S0out_i <= '0';

      S1out_i <= '0';

      S2out_i <= '0';

      S3out_i <= '0';

      SLout_i <= '0';

    elsif clk'event and clk = '1' then  -- rising clock edge

      if S0en = '1' then

        S0out_i <= S0in;

      else

        S0out_i <= S0out_i;

      end if;

      -- Flag Model Input Registers

      --S1

      if S1en = '1' then

        S1i <= S1in;

      elsif RefCnt = REFRESHING_CLK_CYC then

        S1i <= S1out_i;

      else

        S1i <= 'Z';

      end if;

      --S2

      if S2en = '1' then

        S2i <= S2in;

      elsif RefCnt = REFRESHING_CLK_CYC then

        S2i <= S2out_i;

      else

        S2i <= 'Z';

      end if;

      --S3

      if S3en = '1' then

        S3i <= S3in;

      elsif RefCnt = REFRESHING_CLK_CYC then

        S3i <= S3out_i;

      else

        S3i <= 'Z';

      end if;

      --SL

      if SLen = '1' then

        SLi <= SLin;

      elsif RefCnt = REFRESHING_CLK_CYC then

        SLi <= SLout_i;

      else

        SLi <= 'Z';

      end if;

      -- Flag Model Output Registers

      S1out_i <= S1o;

      S2out_i <= S2o;

      S3out_i <= S3o;

      SLout_i <= SLo;

    end if;

  end process REGISTERS;

  REF_COUNTER : process (clk, rst_n)

  begin  -- process REF_COUNTER

    if rst_n = '0' then                 -- asynchronous reset (active low)

      RefCnt <= 0;

    elsif clk'event and clk = '1' then  -- rising clock edge

      if RefCnt = REFRESHING_CLK_CYC then

        RefCnt <= 0;

      else

        RefCnt <= RefCnt + 1;

      end if;

    end if;

  end process REF_COUNTER;

  InvSelFlag_i : InvSelFlag

    port map (

      S1i => S1i,

      S2i => S2i,

      S3i => S3i,

      SLi => SLi,

      S1o => S1o,

      S2o => S2o,

      S3o => S3o,

      SLo => SLo);

-- synopsys synthesis_on

end FlagController1;