rtl/vhdl/c4m_jtag_tap_controller.vhdl

   1 -- A JTAG complient tap controller implementation
   2 -- This is implemented based on the IEEE 1149.1 standard
   3
   4 library ieee;
   5 use ieee.std_logic_1164.ALL;
   6
   7 use work.c4m_jtag.ALL;
   8
   9 entity c4m_jtag_tap_controller is
  10   generic (
  11     DEBUG:              boolean := false;
  12
  13     IR_WIDTH:           integer := 2;
  14     IOS:                integer := 1;
  15
  16     MANUFACTURER:       std_logic_vector(10 downto 0) := "10001111111";
  17     PART_NUMBER:        std_logic_vector(15 downto 0) := "0000000000000001";
  18     VERSION:            std_logic_vector(3 downto 0) := "0000"
  19   );
  20   port (
  21     -- The TAP signals
  22     TCK:        in std_logic;
  23     TMS:        in std_logic;
  24     TDI:        in std_logic;
  25     TDO:        out std_logic;
  26     TRST_N:     in std_logic;
  27
  28     -- The FSM state indicators
  29     RESET:      out std_logic;
  30     DRCAPTURE:  out std_logic;
  31     DRSHIFT:    out std_logic;
  32     DRUPDATE:   out std_logic;
  33
  34     -- The Instruction Register
  35     IR:         out std_logic_vector(IR_WIDTH-1 downto 0);
  36
  37     -- The I/O access ports
  38     CORE_IN:    out std_logic_vector(IOS-1 downto 0);
  39     CORE_EN:    in std_logic_vector(IOS-1 downto 0);
  40     CORE_OUT:   in std_logic_vector(IOS-1 downto 0);
  41
  42     -- The pad connections
  43     PAD_IN:     in std_logic_vector(IOS-1 downto 0);
  44     PAD_EN:     out std_logic_vector(IOS-1 downto 0);
  45     PAD_OUT:    out std_logic_vector(IOS-1 downto 0)
  46   );
  47 end c4m_jtag_tap_controller;
  48
  49 architecture rtl of c4m_jtag_tap_controller is
  50   signal S_STATE:       TAPSTATE_TYPE;
  51   signal S_NEXT_STATE:  TAPSTATE_TYPE;
  52   signal S_IRSTATE:     std_logic;
  53   signal S_DRSTATE:     std_logic;
  54   signal S_IR:          std_logic_vector(IR_WIDTH-1 downto 0);
  55
  56   signal IR_TDO:        std_logic;
  57   signal IR_TDO_EN:     std_logic;
  58   signal ID_TDO:        std_logic;
  59   signal ID_TDO_EN:     std_logic;
  60   signal IO_TDO:        std_logic;
  61   signal IO_TDO_EN:     std_logic;
  62 begin
  63   IR <= S_IR;
  64
  65   RESET     <= '1' when S_STATE = TestLogicReset              else '0';
  66   DRCAPTURE <= '1' when S_STATE = Capture and S_DRSTATE = '1' else '0';
  67   DRSHIFT   <= '1' when S_STATE = Shift   and S_DRSTATE = '1' else '0';
  68   DRUPDATE  <= '1' when S_STATE = Update  and S_DRSTATE = '1' else '0';
  69
  70   -- JTAG state machine
  71   FSM:  c4m_jtag_tap_fsm
  72     port map (
  73       TCK => TCK,
  74       TMS => TMS,
  75       TRST_N => TRST_N,
  76       STATE => S_STATE,
  77       NEXT_STATE => S_NEXT_STATE,
  78       DRSTATE => S_DRSTATE,
  79       IRSTATE => S_IRSTATE
  80     );
  81
  82   -- The instruction register
  83   IRBLOCK: c4m_jtag_irblock
  84     generic map (
  85       IR_WIDTH => IR_WIDTH
  86     )
  87     port map (
  88       TCK => TCK,
  89       TDI => TDI,
  90       TDO => IR_TDO,
  91       TDO_EN => IR_TDO_EN,
  92       STATE => S_STATE,
  93       NEXT_STATE => S_NEXT_STATE,
  94       IRSTATE => S_IRSTATE,
  95       IR => S_IR
  96     );
  97
  98   -- The ID
  99   IDBLOCK: c4m_jtag_idblock
 100     generic map (
 101       IR_WIDTH => IR_WIDTH,
 102       PART_NUMBER => PART_NUMBER,
 103       MANUFACTURER => MANUFACTURER
 104     )
 105     port map (
 106       TCK => TCK,
 107       TDI => TDI,
 108       TDO => ID_TDO,
 109       TDO_EN => ID_TDO_EN,
 110       STATE => S_STATE,
 111       NEXT_STATE => S_NEXT_STATE,
 112       DRSTATE => S_DRSTATE,
 113       IR => S_IR
 114     );
 115
 116   -- The IOS
 117   IOBLOCK: c4m_jtag_ioblock
 118     generic map (
 119       IR_WIDTH => IR_WIDTH,
 120       IOS => IOS
 121     )
 122     port map (
 123       TCK => TCK,
 124       TDI => TDI,
 125       TDO => IO_TDO,
 126       TDO_EN => IO_TDO_EN,
 127       STATE => S_STATE,
 128       NEXT_STATE => S_NEXT_STATE,
 129       DRSTATE => S_DRSTATE,
 130       IR => S_IR,
 131       CORE_OUT => CORE_OUT,
 132       CORE_IN => CORE_IN,
 133       CORE_EN => CORE_EN,
 134       PAD_OUT => PAD_OUT,
 135       PAD_IN => PAD_IN,
 136       PAD_EN => PAD_EN
 137     );
 138
 139   TDO <= IR_TDO when IR_TDO_EN = '1' else
 140          ID_TDO when ID_TDO_EN = '1' else
 141          IO_TDO when IO_TDO_EN = '1' else
 142          '0';
 143
 144   CHECK_EN: if DEBUG generate
 145     signal EN:  std_logic_vector(2 downto 0) := "000";
 146   begin
 147     EN <= IR_TDO_EN & ID_TDO_EN & IO_TDO_EN;
 148     assert EN = "000" or EN = "100" or EN = "010" or EN = "001"
 149       report "TDO conflict in c4m_jtag_tap_controller"
 150       severity ERROR;
 151   end generate CHECK_EN;
 152 end rtl;
 153
 154