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