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------------------------------------------------------------------------------- -- -- The Wishbone master module. -- -- $Id: wb_master.vhd,v 1.5 2005-06-11 10:16:05 arniml Exp $ -- -- Copyright (c) 2005, Arnim Laeuger (arniml@opencores.org) -- -- All rights reserved -- -- Redistribution and use in source and synthezised forms, with or without -- modification, are permitted provided that the following conditions are met: -- -- Redistributions of source code must retain the above copyright notice, -- this list of conditions and the following disclaimer. -- -- Redistributions in synthesized form must reproduce the above copyright -- notice, this list of conditions and the following disclaimer in the -- documentation and/or other materials provided with the distribution. -- -- Neither the name of the author nor the names of other contributors may -- be used to endorse or promote products derived from this software without -- specific prior written permission. -- -- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" -- AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, -- THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR -- PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE -- LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR -- CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF -- SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS -- INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN -- CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) -- ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE -- POSSIBILITY OF SUCH DAMAGE. -- -- Please report bugs to the author, but before you do so, please -- make sure that this is not a derivative work and that -- you have the latest version of this file. -- -- The latest version of this file can be found at: -- http://www.opencores.org/cvsweb.shtml/t48/ -- -- -- Short description: -- This design implements a simple Wishbone bus master. It connects to the -- BUS interface of the T48 uController core. -- -- The CPU clock is suppressed with en_clk_o to stall the CPU until the -- acknowledge signal from the peripheral is detected. -- -- The adr_i input selects between configuration and Wishbone address range: -- 1 - configuration range -- 0 - Wishbone range -- -- When configuration range is selected, two address register are accessible. -- 000h -> adr1 -- 001h -> adr2 -- These registers can be read and written with movx to their addresses. -- -- When Wishbone range is selected, all movx generate Wishbone bus cycles -- (either read or write) at following address: -- Wishbone address = adr2 & adr1 & address of movx -- ------------------------------------------------------------------------------- library ieee; use ieee.std_logic_1164.all; use work.t48_pack.all; entity t48_wb_master is port ( xtal_i : in std_logic; res_i : in std_logic; en_clk_o : out std_logic; -- T48 Interface ---------------------------------------------------------- ale_i : in std_logic; rd_n_i : in std_logic; wr_n_i : in std_logic; adr_i : in std_logic; db_bus_i : in std_logic_vector( 7 downto 0); db_bus_o : out std_logic_vector( 7 downto 0); -- Wishbone Interface ----------------------------------------------------- wb_cyc_o : out std_logic; wb_stb_o : out std_logic; wb_we_o : out std_logic; wb_adr_o : out std_logic_vector(23 downto 0); wb_ack_i : in std_logic; wb_dat_i : in std_logic_vector( 7 downto 0); wb_dat_o : out std_logic_vector( 7 downto 0) ); end t48_wb_master; architecture rtl of t48_wb_master is ----------------------------------------------------------------------------- -- Controller FSM ----------------------------------------------------------------------------- type state_t is (IDLE, CYC, WAIT_INACT); signal state_s, state_q : state_t; ----------------------------------------------------------------------------- -- Select signals for each range ----------------------------------------------------------------------------- signal sel_adr1_s, sel_adr2_s, sel_wb_s : boolean; signal wr_s, rd_s : boolean; signal adr_q : std_logic_vector(23 downto 0); signal wb_dat_q : std_logic_vector( 7 downto 0); begin ----------------------------------------------------------------------------- -- Select signal generation ----------------------------------------------------------------------------- sel_adr1_s <= adr_i = '1' and adr_q(word_t'range) = "00000000"; sel_adr2_s <= adr_i = '1' and adr_q(word_t'range) = "00000001"; sel_wb_s <= adr_i = '0'; wr_s <= wr_n_i = '0'; rd_s <= rd_n_i = '0'; ----------------------------------------------------------------------------- -- Process seq -- -- Purpose: -- Implements the sequential elements. -- seq: process (res_i, xtal_i) begin if res_i = res_active_c then adr_q <= (others => '0'); wb_dat_q <= (others => '0'); state_q <= IDLE; elsif xtal_i'event and xtal_i = clk_active_c then -- Address register ----------------------------------------------------- -- update lowest address byte if ale_i = '1' then adr_q(word_t'range) <= db_bus_i; end if; -- set adr1 part if wr_s and sel_adr1_s then adr_q(word_t'length*2 - 1 downto word_t'length) <= db_bus_i; end if; -- set adr2 part if wr_s and sel_adr2_s then adr_q(word_t'length*3 - 1 downto word_t'length*2) <= db_bus_i; end if; -- Data from peripheral has to be saved --------------------------------- if wb_ack_i = '1' then wb_dat_q <= wb_dat_i; end if; -- FSM state ------------------------------------------------------------ state_q <= state_s; end if; end process seq; -- ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- -- Process fsm -- -- Purpose: -- Implements the state transitions of the controller FSM. -- fsm: process (state_q, wr_s, rd_s, sel_wb_s, wb_ack_i) begin -- default assignments wb_cyc_o <= '0'; wb_stb_o <= '0'; en_clk_o <= '1'; state_s <= IDLE; case state_q is -- Idle State: Wait for read or write access ---------------------------- when IDLE => if sel_wb_s and (wr_s or rd_s) then state_s <= CYC; end if; -- WB Cycle State: Start Wishbone cycle and wait for ack ---------------- when CYC => wb_cyc_o <= '1'; wb_stb_o <= '1'; en_clk_o <= '0'; if wb_ack_i = '1' then state_s <= WAIT_INACT; else state_s <= CYC; end if; -- Wait inact State: Wait for end of T48 access ------------------------- when WAIT_INACT => if not wr_s and not rd_s then state_s <= IDLE; else state_s <= WAIT_INACT; end if; when others => null; end case; end process fsm; -- ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- -- Output multiplexer ----------------------------------------------------------------------------- db_bus_o <= adr_q(word_t'length*2 - 1 downto word_t'length) when sel_adr1_s else adr_q(word_t'length*3 - 1 downto word_t'length*2) when sel_adr2_s else wb_dat_q; ----------------------------------------------------------------------------- -- Output mapping ----------------------------------------------------------------------------- wb_adr_o <= adr_q; wb_dat_o <= db_bus_i; wb_we_o <= '1' when wr_s and sel_wb_s else '0'; end rtl; ------------------------------------------------------------------------------- -- File History: -- -- $Log: not supported by cvs2svn $ -- Revision 1.4 2005/05/10 22:36:23 arniml -- save data from wishbone bus in register bank with wb_ack -- necessary to hold data from peripheral/memory until it is read by T48 -- -- Revision 1.3 2005/05/08 10:36:07 arniml -- simplify address range: -- - configuration range -- - Wishbone range -- -- Revision 1.2 2005/05/06 18:54:03 arniml -- assign default for state_s -- -- Revision 1.1 2005/05/05 19:49:03 arniml -- initial check-in -- -------------------------------------------------------------------------------
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