Subversion Repositories lcd_block

`timescale 1ns / 1ps

module lcd_controller(

    input rst,

    input clk,

    input rs_in,

         input [7:0] data_in,

    input strobe_in,

    input [7:0] period_clk_ns,

    output lcd_e,

    output [3:0] lcd_nibble,

    output lcd_rs,

    output lcd_rw,

    output disable_flash,

    output reg done

    );

        // States for FSM that initialize the LCD

        localparam lcd_init_rst = 1;

        localparam lcd_init_wait = 2;

        localparam lcd_init_write_03_01 = 3;

        localparam lcd_init_wait_4ms = 4;

        localparam lcd_init_write_03_02 = 5;

        localparam lcd_init_wait_100us = 6;

        localparam lcd_init_write_03_03 = 7;

        localparam lcd_init_wait_40us = 8;

        localparam lcd_init_write_02 = 9;

        localparam lcd_init_wait_50us = 10;

        localparam lcd_init_state_done = 11;

        localparam lcd_init_strobe = 12;

        reg [3:0] lcd_init_states, lcd_init_state_next; // Declare two variables of 4 bits to hold the FSM states

        reg [23:0] counter_wait_lcd_init;

        reg [8:0] counter_wait_strobe_lcd_init, counter_wait_stabilize_lcd_init;

        reg [23:0] time_wait_lcd_init;

        reg [3:0] lcd_init_data_out;  // FSM output LCD_DATA

        reg lcd_init_e_out;           // FSM output LCD_E

        reg lcd_init_done;

        // States for FSM that send data to LCD

        localparam lcd_data_rst = 1;

        localparam lcd_data_wait_1us = 2;

        localparam lcd_data_wr_nibble_high = 3;

        localparam lcd_data_wr_nibble_low = 4;

        localparam lcd_data_strobe = 5;

        localparam lcd_data_wait_40us = 6;

        localparam lcd_data_done = 7;

        reg [19:0] time_wait_lcd_data;

        reg [19:0] counter_wait_lcd_data;

        reg [8:0] counter_wait_strobe_lcd_data, counter_wait_stabilize_lcd_data;

        reg [3:0] lcd_data_states, lcd_data_state_next;  // Declare two variables of 4 bits to hold the FSM states

        reg [3:0] lcd_data_data_out;     // FSM output LCD_DATA

        reg lcd_data_e_out;                             // FSM output LCD_E

        /*

                Initialize LCD...

        */

        always @ (posedge clk)

        begin

                if (rst)        // Reset synchronous

                        begin

                                lcd_init_states <= lcd_init_rst;

                                counter_wait_lcd_init <= 0;

                                counter_wait_strobe_lcd_init <= 0;

                                counter_wait_stabilize_lcd_init <= 0;

                                lcd_init_e_out <= 0;

                                lcd_init_done <= 0;

                                lcd_init_data_out <= 0;

                        end

                else

                        begin

                                case (lcd_init_states)

                                        lcd_init_rst:

                                                begin

                                                        // Wait for 15ms to power-up LCD

                                                        time_wait_lcd_init <= 15000000;

                                                        lcd_init_states <= lcd_init_wait;

                                                        lcd_init_state_next <= lcd_init_write_03_01;

                                                end

                                        // Wait for a configured time in (ns) and go to other state in (lcd_init_state_next)

                                        lcd_init_wait:

                                                begin

                                                        counter_wait_lcd_init <= counter_wait_lcd_init + period_clk_ns;

                                                        if (counter_wait_lcd_init >= time_wait_lcd_init)

                                                                begin

                                                                        lcd_init_states <= lcd_init_state_next;

                                                                        counter_wait_lcd_init <= 0;

                                                                end

                                                end

                                        // Strobe the LCD for at least 240 ns

                                        lcd_init_strobe:

                                                begin

                                                        // We need to wait at least 40ns to stabilize the data before strobing the data... 

                                                        counter_wait_stabilize_lcd_init <= counter_wait_stabilize_lcd_init + period_clk_ns;

                                                        if (counter_wait_stabilize_lcd_init >= 40)

                                                                begin

                                                                        lcd_init_e_out <= 1;

                                                                        // After we got a strobe high hold for more 240 ns

                                                                        counter_wait_strobe_lcd_init <= counter_wait_strobe_lcd_init + period_clk_ns;

                                                                        if (counter_wait_strobe_lcd_init >= 240)

                                                                                begin

                                                                                        lcd_init_states <= lcd_init_state_next;

                                                                                        counter_wait_stabilize_lcd_init <= 0;

                                                                                        counter_wait_strobe_lcd_init <= 0;

                                                                                        lcd_init_e_out <= 0;

                                                                                end

                                                                end

                                                end

                                        lcd_init_write_03_01:

                                                // Send 0x3 and pulse LCD_E for 240ns 

                                                begin

                                                        lcd_init_data_out <= 4'h3;

                                                        lcd_init_states <= lcd_init_strobe;     // Strobe for at least 230 ns                                           

                                                        lcd_init_state_next <= lcd_init_wait_4ms;

                                                end

                                        lcd_init_wait_4ms:

                                                begin

                                                        time_wait_lcd_init <= 4100000;  // Wait for 4.1ms

                                                        lcd_init_states <= lcd_init_wait;

                                                        lcd_init_state_next <= lcd_init_write_03_02;

                                                end

                                        lcd_init_write_03_02:

                                                // Send 0x3 and pulse LCD_E for 240ns 

                                                begin

                                                        lcd_init_data_out <= 4'h3;

                                                        lcd_init_states <= lcd_init_strobe;     // Strobe for at least 230 ns                                           

                                                        lcd_init_state_next <= lcd_init_wait_100us;

                                                end

                                        lcd_init_wait_100us:

                                                begin

                                                        time_wait_lcd_init <= 100000;   // Wait for 100us

                                                        lcd_init_states <= lcd_init_wait;

                                                        lcd_init_state_next <= lcd_init_write_03_03;

                                                end

                                        lcd_init_write_03_03:

                                                // Send 0x3 and pulse LCD_E for 240ns 

                                                begin

                                                        lcd_init_data_out <= 4'h3;

                                                        lcd_init_states <= lcd_init_strobe;     // Strobe for at least 230 ns                                           

                                                        lcd_init_state_next <= lcd_init_wait_40us;

                                                end

                                        lcd_init_wait_40us:

                                                begin

                                                        time_wait_lcd_init <= 40000;    // Wait for 40us

                                                        lcd_init_states <= lcd_init_wait;

                                                        lcd_init_state_next <= lcd_init_write_02;

                                                end

                                        lcd_init_write_02:

                                                // Send 0x2 and pulse LCD_E for 240ns 

                                                begin

                                                        lcd_init_data_out <= 4'h2;

                                                        lcd_init_states <= lcd_init_strobe;     // Strobe for at least 230 ns                                           

                                                        lcd_init_state_next <= lcd_init_wait_50us;

                                                end

                                        lcd_init_wait_50us:

                                                begin

                                                        time_wait_lcd_init <= 50000;    // Wait for 50us

                                                        lcd_init_states <= lcd_init_wait;

                                                        lcd_init_state_next <= lcd_init_state_done;

                                                end

                                        lcd_init_state_done:

                                                begin

                                                        lcd_init_done <= 1;

                                                        lcd_init_state_next <= lcd_init_state_done;

                                                end

                                endcase

                        end

        end

        // On the most cases you can only write to the display...

        assign lcd_rw = 0;

        assign lcd_rs = rs_in;

        assign disable_flash = 1;

        // Will assign the output of the FSM init or the FSM data depending if initialization is already done

        assign lcd_e = (!lcd_init_done) ? lcd_init_e_out : lcd_data_e_out;

        assign lcd_nibble = (!lcd_init_done) ? lcd_init_data_out : lcd_data_data_out ;

        /*

                FSM that deals to send data to the LCD (nibble High + nibble Low)

        */

        always @ (posedge clk)

        begin

                if (~lcd_init_done)

                        begin

                                lcd_data_e_out <= 0;

                                lcd_data_data_out <= 0;

                                lcd_data_states <= lcd_data_rst;

                                done <= 0;

                                counter_wait_stabilize_lcd_data <= 0;

                                counter_wait_lcd_data <= 0;

                                counter_wait_strobe_lcd_data <= 0;

                        end

                else

                        begin

                                case (lcd_data_states)

                                        lcd_data_rst:

                                                begin

                                                        done <= 0;

                                                        // Start to send data when strobe_in =1

                                                        if (strobe_in == 1)

                                                                begin

                                                                        lcd_data_states <= lcd_data_wr_nibble_high;

                                                                end

                                                        else

                                                                lcd_data_states <= lcd_data_rst;

                                                end

                                        lcd_data_wr_nibble_high:

                                                begin

                                                        // First send the high nibble

                                                        lcd_data_data_out <= data_in[7:4];

                                                        lcd_data_states <= lcd_data_strobe;

                                                        lcd_data_state_next <= lcd_data_wait_1us;

                                                end

                                        lcd_data_strobe:

                                                begin

                                                        // We need to wait at least 40ns to stabilize the data before strobing the data... 

                                                        counter_wait_stabilize_lcd_data <= counter_wait_stabilize_lcd_data + period_clk_ns;

                                                        if (counter_wait_stabilize_lcd_data >= 40)

                                                                begin

                                                                        lcd_data_e_out <= 1;

                                                                        // After we got a strobe high hold for more 240 ns

                                                                        counter_wait_strobe_lcd_data <= counter_wait_strobe_lcd_data + period_clk_ns;

                                                                        if (counter_wait_strobe_lcd_data >= 240)

                                                                                begin

                                                                                        lcd_data_states <= lcd_data_state_next;

                                                                                        counter_wait_stabilize_lcd_data <= 0;

                                                                                        counter_wait_strobe_lcd_data <= 0;

                                                                                        lcd_data_e_out <= 0;

                                                                                end

                                                                end

                                                end

                                        // Wait for 1us before sending the low nibble

                                        lcd_data_wait_1us:

                                                begin

                                                        counter_wait_lcd_data <= counter_wait_lcd_data + period_clk_ns;

                                                        if (counter_wait_lcd_data >= 1000)

                                                                begin

                                                                        lcd_data_states <= lcd_data_wr_nibble_low;

                                                                        counter_wait_lcd_data <= 0;

                                                                end

                                                end

                                        lcd_data_wr_nibble_low:

                                                begin

                                                        // After send the low nibble

                                                        lcd_data_data_out <= data_in[3:0];

                                                        lcd_data_states <= lcd_data_strobe;

                                                        lcd_data_state_next <= lcd_data_wait_40us;

                                                end

                                        // Wait for 40us before sending the next byte

                                        lcd_data_wait_40us:

                                                begin

                                                        counter_wait_lcd_data <= counter_wait_lcd_data + period_clk_ns;

                                                        if (counter_wait_lcd_data >= 40000)

                                                                begin

                                                                        lcd_data_states <= lcd_data_done;

                                                                        counter_wait_lcd_data <= 0;

                                                                end

                                                end

                                        lcd_data_done:

                                                begin

                                                        // Signal that we done sending the data

                                                        done <= 1;

                                                        lcd_data_states <= lcd_data_rst;

                                                end

                                endcase

                        end

        end

endmodule