Subversion Repositories wb_lcd

//////////////////////////////////////////////////////////////////////

////                                                              ////

////  wb_lcd.v                                                    ////

////                                                              ////

////  This file is part of:                                       ////

////  WISHBONE/MEM MAPPED CONTROLLER FOR LCD CHARACTER DISPLAYS   ////

////  http://www.opencores.org/projects/wb_lcd/                   ////

////                                                              ////

////  Description                                                 ////

////   -  Wishbone wrapper.                                       ////

////                                                              ////

////  To Do:                                                      ////

////   - nothing really                                           ////

////                                                              ////

////  Author(s):                                                  ////

////   - José Ignacio Villar, jose@dte.us.es , jvillar@gmail.com  ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

////                                                              ////

//// Copyright (C) 2009 José Ignacio Villar - jvillar@gmail.com   ////

////                                                              ////

//// This source file may be used and distributed without         ////

//// restriction provided that this copyright statement is not    ////

//// removed from the file and that any derivative work contains  ////

//// the original copyright notice and the associated disclaimer. ////

////                                                              ////

//// This source file is free software; you can redistribute it   ////

//// and/or modify it under the terms of the GNU Lesser General   ////

//// Public License as published by the Free Software Foundation; ////

//// either version 3 of the License, or (at your option) any     ////

//// later version.                                               ////

////                                                              ////

//// This source is distributed in the hope that it will be       ////

//// useful, but WITHOUT ANY WARRANTY; without even the implied   ////

//// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR      ////

//// PURPOSE.  See the GNU Lesser General Public License for more ////

//// details.                                                     ////

////                                                              ////

//// You should have received a copy of the GNU Lesser General    ////

//// Public License along with this source; if not, download it   ////

//// from http://www.gnu.org/licenses/lgpl.txt                    ////

////                                                              ////

//////////////////////////////////////////////////////////////////////

`include "lcd_defines.v"

module wb_lcd (

        //

        // I/O Ports

        //

        input                   wb_clk_i,

        input                   wb_rst_i,

        //

        // WB slave interface

        //

        input   [`WB_DAT_RNG]   wb_dat_i,

        output  reg [`WB_DAT_RNG]       wb_dat_o,

        input   [`WB_ADDR_RNG]  wb_adr_i,

        input   [`WB_BSEL_RNG]  wb_sel_i,

        input                   wb_we_i,

        input                   wb_cyc_i,

        input                   wb_stb_i,

        output  reg             wb_ack_o,

        output                  wb_err_o,

        //

        // LCD interface

        //

        output  [3:0]            SF_D,

        output                  LCD_E,

        output                  LCD_RS,

        output                  LCD_RW

        );

assign wb_err_o = 0;

wire cs = wb_cyc_i & wb_stb_i;

wire we = cs & wb_we_i;

wire re = cs & !wb_we_i;

wire special_address = (`SPECIAL_REG_ADDR_MASK == (`SPECIAL_REG_ADDR_MASK & wb_adr_i));

wire lcd_busy;

wire lcd_we = !special_address & we;

wire [`ADDR_WIDTH-1:0] lcd_addr = wb_adr_i[`ADDR_WIDTH-1:0];

wire repaint_req =  we & (wb_adr_i == `COMMAND_REG_ADDR) & (wb_dat_i == `COMMAND_REPAINT_CODE);

wire status = lcd_busy ? `STATUS_BUSY_CODE : `STATUS_IDDLE_CODE;

// wb_ack management: two clk cycles per WB access to avoid long combinational paths.

always @(posedge wb_clk_i) begin

        if(wb_rst_i)

                wb_ack_o <= 1'b0;

        else begin

                if(cs)

                        wb_ack_o <= ~wb_ack_o;

                else

                        wb_ack_o <= 1'b0;

        end

end

// Status register (only checks if lcd is busy)

always @(posedge wb_clk_i) // wb_dat_o always outputs the status register not depending on what address is being accessed

        wb_dat_o = status;

// Command register (only issues repaint commands)

reg lcd_repaint = 0;

always @(posedge wb_clk_i) begin

        if(repaint_req & !lcd_busy)

                lcd_repaint <= 1;

        else

                lcd_repaint <= 0;

end

//----------------------------------------------------------------------------

// Memory mapped LCD display controller

//----------------------------------------------------------------------------

lcd lcd(

        .clk    ( wb_clk_i ),

        .reset  ( wb_rst_i ),

        .dat    ( wb_dat_i[`DAT_RNG] ),

        .addr   ( lcd_addr ),

        .we     ( lcd_we ),

        .repaint( lcd_repaint ),

        .busy   ( lcd_busy ),

        .SF_D   ( SF_D ),

        .LCD_E  ( LCD_E ),

        .LCD_RS ( LCD_RS ),

        .LCD_RW ( LCD_RW )

        );

endmodule