AHB-Lite Interface

Example Code

   -------------------------------------------
   -- Support Package for AHB-Lite Protocol --
   -------------------------------------------
   library ieee;
   context ieee.ieee_std_context;

   package amba_ahbl_pkg
      generic(
         slaves_max_jg : positive := 3
      );
      is
      constant slaves_total_jc    : positive := slaves_max_jg;     -- individual slaves
      subtype  slaves_total_jrt  is natural range slaves_total_jc downto 1;

      -------------------------------------------
      -- Base types for AMBA AHB-Lite Protocol --
      -------------------------------------------
      -- AHBL Slave Select bus
      subtype  HSEL_vst          is std_logic_vector(slaves_total_jrt);

      -- AHBL Address bus
      constant HADDR_width_jc     : positive := 32;
      subtype  HADDR_jrt         is natural range HADDR_width_jc- 1 downto 0;
      subtype  HADDR_vst         is std_logic_vector(HADDR_jrt);

      -- AHBL Size control
      constant HSIZE_width_jc     : positive := 3;
      subtype  HSIZE_jrt         is natural range HSIZE_width_jc- 1 downto 0;
      subtype  HSIZE_vst         is std_logic_vector(HSIZE_jrt);

      -- AHBL Burst control
      constant HBURST_width_jc     : positive := 3;
      subtype  HBURST_jrt         is natural range HBURST_width_jc- 1 downto 0;
      subtype  HBURST_vst         is std_logic_vector(HBURST_jrt);

      -- AHBL Protection control
      constant HPROT_width_jc     : positive := 4;
      subtype  HPROT_jrt         is natural range HPROT_width_jc- 1 downto 0;
      subtype  HPROT_vst         is std_logic_vector(HPROT_jrt);

      -- AHBL Transfer Type control
      constant HTRANS_width_jc     : positive := 2;
      subtype  HTRANS_jrt         is natural range HTRANS_width_jc- 1 downto 0;
      subtype  HTRANS_vst         is std_logic_vector(HTRANS_jrt);

      -- AHBL Data bus
      constant HDATA_width_jc     : positive := 32;
      subtype  HDATA_jrt         is natural range HDATA_width_jc- 1 downto 0;
      subtype  HDATA_vst         is std_logic_vector(HDATA_jrt);

      -----------------------------------------------------
      -- Record & Array Types for AMBA AHB-Lite Protocol --
      -----------------------------------------------------
      -- Global control record for AMBA AHB-Lite bus
      type g_amba_ahb_rt is -- AMBA AHBL global record
         record
            HRESET_nl   : std_logic;     -- AHBL global reset
            HCLK_l      : std_logic;     -- AHBL global clock
         end record g_amba_ahb_rt;

      -- Slave record for AMBA AHB-Lite bus
      type s_amba_ahb_rt is -- AMBA AHBL slave return record
         record
            HREADYOUT_l : std_logic;     -- AHBL transfer complete
            HRESP_l     : std_logic;     -- AHBL transfer response
            HRDATA_vl   : HDATA_vst;     -- AHBL read data bus (32bit)
         end record s_amba_ahb_rt;

      -- Slave array for AMBA AHB-Lite bus
      type s_amba_ahb_at is
         array(slaves_total_jrt)
            of s_amba_ahb_rt;             -- Array of slave return records

      -- Master record for AMBA AHB-Lite bus
      type m_amba_ahb_rt is -- AMBA AHBL master record
         record
            HREADY_l    : std_logic;     -- AHBL transfer complete
            HADDR_vl    : HADDR_vst;     -- AHBL address bus (32bit)
            HWRITE_l    : std_logic;     -- AHBL transfer write/read control
            HSIZE_vl    : HSIZE_vst;     -- AHBL transfer size control (3bit)
            HBURST_vl   : HBURST_vst;    -- AHBL transfer burst control (3bit)
            HPROT_vl    : HPROT_vst;     -- AHBL access protection control (4bit)
            HTRANS_vl   : HTRANS_vst;    -- AHBL transfer type control (2bit)
            HMASTLOCK_l : std_logic;     -- AHBL locked transfer control
            HWDATA_vl   : HDATA_vst;     -- AHBL write data bus (32bit)
         end record m_amba_ahb_rt;

      --------------------------------------------------------
      -- Record & Array Mode Views for AHBL Composite Types --
      --------------------------------------------------------

      -- Mode view only required for master connection - slave connection is
      -- all of mode 'in'.
      -- Decoder and multiplexor function inputs by default are of mode 'in'.
      record view m_amba_ahb_rvw of m_amba_ahb_rt is
         element(
            HREADY_l    : in     std_logic;
            HADDR_vl    : out    HADDR_vst;
            HWRITE_l    : out    std_logic;
            HSIZE_vl    : out    HSIZE_vst;
            HBURST_vl   : out    HBURST_vst;
            HPROT_vl    : out    HPROT_vst;
            HTRANS_vl   : out    HTRANS_vst;
            HMASTLOCK_l : out    std_logic;
            HRDATA_vl   : out    HDATA_vst;
         );
      end record view m_amba_ahb_rvw;

      -----------------------------------------
      -- Decoder and Multiplexor Subprograms --
      -----------------------------------------
      -- Slave select decoder function
      function HSEL_decoder_f(;
            g_amba_ahb_ri : g_amba_ahb_rt;
            m_amba_ahb_ri : m_amba_ahb_rt
         ) return HSEL_vst;

      -- Slave return multiplexor function
      function slave_multiplexor_f(;
            g_amba_ahb_ri : g_amba_ahb_rt;
            m_amba_ahb_ri : m_amba_ahb_rt;
            s_amba_ahb_ai : s_amba_ahb_at
         ) return s_amba_ahb_rt;

      --------------------------------
      -- Context Clause for Package --
      --------------------------------
      context amba_ahbl_context;
         library ieee;
         context ieee.ieee_std_context;
            use work.amba_ahbl_pkg.all;
      end context amba_ahbl_context;
   end package amba_ahbl_pkg;

   -- A package body is required to define the decoder and multiplexor
   -- functions.
   package body amba_ahbl_pkg;
      -----------------------------------------
      -- Decoder and Multiplexor Subprograms --
      -----------------------------------------
      -- Slave select decoder function
      function HSEL_decoder_f(;
            g_amba_ahb_ri : g_amba_ahb_rt;
            m_amba_ahb_ri : m_amba_ahb_rt
         ) return HSEL_vst is
         variable HSEL_vv : HSEL_vst;
      begin
         ...
         return HSEL_vv;
      end function HSEL_decoder_f;

      -- Slave return multiplexor function
      function slave_multiplexor_f(;
            g_amba_ahb_ri : g_amba_ahb_rt;
            m_amba_ahb_ri : m_amba_ahb_rt;
            s_amba_ahb_ai : s_amba_ahb_at
         ) return s_amba_ahb_rt is
         variable s_amba_ahb_rv : s_amba_ahb_rt;
      begin
         ...
         return s_amba_ahb_rv;
      end function HSEL_decode_f;
   end package body amba_ahbl_pkg;

   -----------------------------------------------------------------
   -- Declare entities for AHBL Master, Slave and top-level Block --
   -----------------------------------------------------------------
   -- AHB-Lite Master Entity
   context work.amba_ahbl_context;
   entity ahbl_master_ent is(
      port(
         g_amba_ahb_ri  : in     g_amba_ahb_rt;
         s_amba_ahb_ri  : in     s_amba_ahb_rt;
         m_amba_ahb_rif : view   m_amba_ahb_rt(m_amba_ahb_rvw)
      );
   end entity ahbl_master_ent;
   architecture rtl_arch of ahbl_master_ent is
   begin(
      ....
   end architecture rtl_arch;

   -- AHB-Lite Slave Entity
   context work.amba_ahbl_context;
   entity ahbl_slave_ent is(
      port(
         g_amba_ahb_ri : in     g_amba_ahb_rt;
         HSEL_i        : in     std_logic;
         m_amba_ahb_ri : in     m_amba_ahb_rt;
         s_amba_ahb_ro : out    s_amba_ahb_rt
      );
   end entity ahbl_slave_ent;
   architecture rtl_arch of ahbl_slave_ent is
   begin(
      ....
   end architecture rtl_arch;

   ---------------
   -- Top Level --
   ---------------
   -- Top-level AHB-Lite Block Structure
   context work.amba_ahbl_context;
   entity ahbl_block_ent is(
   end entity ahbl_block_ent;

   architecture rtl_arch of ahbl_block_ent is
      signal g_amba_ahb_rs : g_amba_ahb_rt;
      signal m_amba_ahb_rs : m_amba_ahb_rt;
      signal HSEL_vs       : HSEL_vst;
      signal s_amba_ahb_rs : s_amba_ahb_rt;
      signal s_amba_ahb_as : s_amba_ahb_at;
   begin(

      -- Clock and Reset Control for AHB-Lite Block
      clk_and_rst_inst : entity clk_and_rst_ent(rtl_arch)
         port map(
            rst_o => g_amba_ahb_rs.HRESET_nl,
            clk_o => g_amba_ahb_rs.HCLK_l
         );

      -- Master Instantiation for AHB-Lite Block
      ahbl_master_inst : entity ahbl_master_ent(rtl_arch)
         port map(
            g_amba_ahb_ri  => g_amba_ahb_rs,
            s_amba_ahb_ri  => s_amba_ahb_rs,
            m_amba_ahb_rif => m_amba_ahb_rs
         );

      -- Slave Decoder
      HSEL_decoder_asgn :
         HSEL_vs                <= HSEL_decoder_f(g_amba_ahb_rs,m_amba_ahb_rs);

      -- Slave Multiplexor
      slave_multiplexor_asgn :
         s_amba_ahb_rs          <= slave_multiplexor_f(g_amba_ahb_rs,m_amba_ahb_rs, s_amba_ahb_as);

      -- HREADY decode
      HREADY_asgn :
         m_amba_ahb_rs.HREADY_l <= s_amba_ahb_rs.HREADYOUT_l;

      -- Slave Instantiations for AHB-Lite Block
      ahbl_slave3_inst : entity ahbl_slave_ent(rtl_arch)
         port map(
            g_amba_ahb_ri => g_amba_ahb_rs,
            HSEL_i        => HSEL_vs(3),
            m_amba_ahb_ri => m_amba_ahb_rs,
            s_amba_ahb_ro => s_amba_ahb_as(3)
         );
      ahbl_slave2_inst : entity ahbl_slave_ent(rtl_arch)
         port map(
            g_amba_ahb_ri => g_amba_ahb_rs,
            HSEL_i        => HSEL_vs(2),
            m_amba_ahb_ri => m_amba_ahb_rs,
            s_amba_ahb_ro => s_amba_ahb_as(2)
         );
      ahbl_slave1_inst : entity ahbl_slave_ent(rtl_arch)
         port map(
            g_amba_ahb_ri => g_amba_ahb_rs,
            HSEL_i        => HSEL_vs(1),
            m_amba_ahb_ri => m_amba_ahb_rs,
            s_amba_ahb_ro => s_amba_ahb_as(1)
         );
   end architecture rtl_arch;

Interface Connections

-- Brent Hayhoe - 2016-09-09

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