Subversion Repositories 16x2_lcd_display_driver

/*

16x2 LCD DEMO

DESCRIPTION

        Demo for 16X2 LCD.

        Example Hello World!

IO DETAILS

        clk             >>      Clock

        rst             >>      Reset

        start   >>      Start process

        rs              >>      LCD Register select

        en              >>      LCD Enable

        lcd_data        >>      LCD Data pins

AUTHOR:

        Name:   Jagadeesh J

        Email:  jagadeeshj@kenosys.in

        Tel:    +91-8098701730

COMPANY:

        KENOSYS EMBEDDED SOLUTIONS, SALEM, TAMILNADU, INDIA

 This program is free software: you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation, either version 3 of the License, or

   (at your option) any later version.

   This program 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 General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program.  If not, see <http://www.gnu.org/licenses/>.

 */

 module lcd_fpga (

        input clk,rst,start,

        output rs,en,

        output [7:0]lcd_data

);

parameter SIZE = 5'd16; //SIZE OF MEMORY

reg [7:0]mem[0:SIZE-1];

reg [7:0]data_reg, data_next;

reg [1:0]state_reg, state_next;

reg [3:0]count_reg, count_next;

reg cd_next, cd_reg;

reg d_start_reg, d_start_next;

wire done_tick;

initial

begin

        mem[0] = 8'h38;          //LCD_mode 8 bit

        mem[1] = 8'h06;         //Entry mode

        mem[2] = 8'h0E;         //Curson on

        mem[3] = 8'h01;         //Clear Display

        mem[4] = 8'h48;         //H

        mem[5] = 8'h45;         //E

        mem[6] = 8'h4C;         //L

        mem[7] = 8'h4C;         //L

        mem[8] = 8'h4F;         //O

        mem[9] = 8'h20;         // 

        mem[10] = 8'h57;        //W     

        mem[11] = 8'h4F;        //O

        mem[12] = 8'h52;        //R

        mem[13] = 8'h4C;        //L

        mem[14] = 8'h44;        //D

        mem[15] = 8'h21;        //!

end

//States

localparam [1:0] IDLE            = 2'b00,

                                        INIT            = 2'b01,

                                        DISP            = 2'b10,

                                        FIN             = 2'b11;

//LCD Driver Instantiation                                      

lcd_16x2_8bit DUT (

        .data(data_reg),

        .clk(clk),

        .rst(rst),

        .start(d_start_reg),

        .cd(cd_reg),

        .lcd_data(lcd_data),

        .rs(rs),

        .en(en),

        .done_tick(done_tick)

        );

always@(posedge clk, negedge rst)

begin

        if(!rst)

        begin

                state_reg       <= IDLE;

                count_reg       <= 0;

                data_reg        <= 0;

                cd_reg          <= 0;

                d_start_reg <= 0;

        end

        else

        begin

                state_reg       <= state_next;

                count_reg       <= count_next;

                data_reg        <= data_next;

                cd_reg          <= cd_next;

                d_start_reg <= d_start_next;

        end

end

always@*

begin

        state_next = state_reg;

        count_next = count_reg;

        data_next = data_reg;

        cd_next = cd_reg;

        d_start_next = d_start_reg;

        case(state_reg)

                IDLE:

                begin

                        if(!start)

                                state_next = INIT;

                end

                INIT:   //LCD INITIALIZE CMDS

                begin

                        data_next = mem[count_reg];

                        d_start_next = 1'b1;

                        cd_next = 0;

                        if(done_tick)

                        begin

                                d_start_next = 0;

                                count_next = count_reg+1'b1;

                                if(count_reg > 8'd2)

                                        state_next = DISP;

                        end

                end

                DISP:   //DISPLAY CHARACTERS

                begin

                        data_next = mem[count_reg];

                        d_start_next = 1'b1;

                        cd_next = 1;

                        if(done_tick)

                        begin

                                d_start_next = 0;

                                count_next = count_reg+1'b1;

                                if(count_reg > SIZE-2)

                                        state_next = FIN;

                        end

                end

                FIN:

                begin

                        data_next = 0;

                        d_start_next = 0;

                        cd_next = 0;

                        state_next = IDLE;

                end

        endcase

end

endmodule