High Levels Logics Design: การทดลองที่ 6 ใช้ IP core สำหรับ 16x2 LCD ที่มีอยู่บนบอร์ด FPGA เพื่อแสดงข้อความ "Hello World!"

ซอฟท์แวร์ที่ใช้

1. Altera Quartus II 13.1 (32-bit) Web Edition- ModelSim

2. Altera 10.1d (Quartus II 13.1)

อุปกรณ์
1. บอร์ด Altera FPGA (WARRIOR CYCLONE3 DEV) ชิปหมายเลข EP3C10E144C8 1 บอร์ด
2. สายดาวน์โหลด ByteBlaster II Cable หรือ สายดาวน์โหลดUSB Blaster Cab 1 ชุด
3. เครื่องคอมพิวเตอร์                                      2 ชุด
4. ออสซิลโลสโคป 1 เครื่อง

ขั้นตอนการทดลอง
1.เข้า web Opencores.org  เพื่อ ดาวน์โหลด IP core
2.ทำการแก้ไขเพื่อให้แสดงข้อความ  "Hello World!" โดยใช้รหัส ASCII
3.คอมไพล์โค้ดที่แก้ไขเสร็จแล้ว จากนั้นทำการ assignment pin ของ 16x2 LCD ตามเอกสาร datasheet

Code VHDL (ส่วนที่แสดงผลบนจอ)

library ieee;
use ieee.std_logic_1164.all;

entity lcd16x2_ctrl is
  port (
    clk    : in  std_logic;
    lcd_e  : out std_logic;
    lcd_rs : out std_logic;
    lcd_rw : out std_logic;
    lcd_db : out std_logic_vector(7 downto 4));

end entity lcd16x2_ctrl;

architecture behavior of lcd16x2_ctrl is

signal timer : natural range 0 to 100000000 := 0;
  signal switch_lines : std_logic := '0';
  signal line1 : std_logic_vector(127 downto 0);
  signal line2 : std_logic_vector(127 downto 0);

constant CLK_PERIOD_NS : positive := 10; -- 100 Mhz

signal rst          : std_logic;
  signal line1_buffer : std_logic_vector(127 downto 0);
  signal line2_buffer : std_logic_vector(127 downto 0);

begin

DUT : entity work.lcd_ip
    generic map (
      CLK_PERIOD_NS => CLK_PERIOD_NS)
    port map (
      clk          => clk,
      rst          => rst,
      lcd_e        => lcd_e,
      lcd_rs       => lcd_rs,
      lcd_rw       => lcd_rw,
      lcd_db       => lcd_db,
      line1_buffer => line1_buffer,
      line2_buffer => line2_buffer);

rst <= '0';

line1(127 downto 120) <= X"20";
  line1(119 downto 112) <= X"20";
  line1(111 downto 104) <= X"48";  -- H
  line1(103 downto 96)  <= X"65";  -- e
  line1(95 downto 88)   <= X"6c";  -- l
  line1(87 downto 80)   <= X"6c";  -- l
  line1(79 downto 72)   <= X"6f";  -- o
  line1(71 downto 64)   <= X"20";
  line1(63 downto 56)   <= X"57";  -- W
  line1(55 downto 48)   <= X"6f";  -- o
  line1(47 downto 40)   <= X"72";  -- r
  line1(39 downto 32)   <= X"6c";  -- l
  line1(31 downto 24)   <= X"64";  -- d
  line1(23 downto 16)   <= X"21";  -- !
  line1(15 downto 8)    <= X"20";
  line1(7 downto 0)     <= X"20";

line2(127 downto 120) <= X"20";
  line2(119 downto 112) <= X"20";
  line2(111 downto 104) <= X"20";
  line2(103 downto 96)  <= X"20";
  line2(95 downto 88)   <= X"47";--G
  line2(87 downto 80)   <= X"41";--A
  line2(79 downto 72)   <= X"4E";--N
  line2(71 downto 64)   <= X"57";--W
  line2(63 downto 56)   <= X"41";--A
  line2(55 downto 48)   <= X"52";--R
  line2(47 downto 40)   <= X"36";--6
  line2(39 downto 32)   <= X"20";
  line2(31 downto 24)   <= X"20";
  line2(23 downto 16)   <= X"20";
  line2(15 downto 8)    <= X"20";
  line2(7 downto 0)     <= X"20";

line1_buffer <= line1;
  line2_buffer <= line2;

process(clk)
  begin
    if rising_edge(clk) then
      if timer = 0 then
        timer <= 100000000;
        switch_lines <= not switch_lines;
      else
        timer <= timer - 1;
      end if;
    end if;
    
  end process;
end architecture behavior;

Code VHDL (LCD ที่ทำเป็น bit IP)

library ieee;
use ieee.std_logic_1164.all;

entity lcd_ip is

generic (
    CLK_PERIOD_NS : positive := 20);    -- 50MHz

port (
    clk          : in  std_logic;
    rst          : in  std_logic;
    lcd_e        : out std_logic;
    lcd_rs       : out std_logic;
    lcd_rw       : out std_logic;
    lcd_db       : out std_logic_vector(7 downto 4);
    line1_buffer : in  std_logic_vector(127 downto 0);  -- 16x8bit
    line2_buffer : in  std_logic_vector(127 downto 0));

end entity lcd_ip;

architecture rtl of lcd_ip is

constant DELAY_15_MS   : positive := 15 * 10**6 / CLK_PERIOD_NS + 1;
  constant DELAY_1640_US : positive := 1640 * 10**3 / CLK_PERIOD_NS + 1;
  constant DELAY_4100_US : positive := 4100 * 10**3 / CLK_PERIOD_NS + 1;
  constant DELAY_100_US  : positive := 100 * 10**3 / CLK_PERIOD_NS + 1;
  constant DELAY_40_US   : positive := 40 * 10**3 / CLK_PERIOD_NS + 1;

constant DELAY_NIBBLE     : positive := 10**3 / CLK_PERIOD_NS + 1;
  constant DELAY_LCD_E      : positive := 230 / CLK_PERIOD_NS + 1;
  constant DELAY_SETUP_HOLD : positive := 40 / CLK_PERIOD_NS + 1;

constant MAX_DELAY : positive := DELAY_15_MS;

type op_t is record
    rs      : std_logic;
    data    : std_logic_vector(7 downto 0);
    delay_h : integer range 0 to MAX_DELAY;
    delay_l : integer range 0 to MAX_DELAY;
  end record op_t;
  constant default_op      : op_t := (rs => '1', data => X"00", delay_h => DELAY_NIBBLE, delay_l => DELAY_40_US);
  constant op_select_line1 : op_t := (rs => '0', data => X"80", delay_h => DELAY_NIBBLE, delay_l => DELAY_40_US);
  constant op_select_line2 : op_t := (rs => '0', data => X"C0", delay_h => DELAY_NIBBLE, delay_l => DELAY_40_US);

type config_ops_t is array(0 to 5) of op_t;
  constant config_ops : config_ops_t
    := (5 => (rs => '0', data => X"33", delay_h => DELAY_4100_US, delay_l => DELAY_100_US),
        4 => (rs => '0', data => X"32", delay_h => DELAY_40_US, delay_l => DELAY_40_US),
        3 => (rs => '0', data => X"28", delay_h => DELAY_NIBBLE, delay_l => DELAY_40_US),
        2 => (rs => '0', data => X"06", delay_h => DELAY_NIBBLE, delay_l => DELAY_40_US),
        1 => (rs => '0', data => X"0C", delay_h => DELAY_NIBBLE, delay_l => DELAY_40_US),
        0 => (rs => '0', data => X"01", delay_h => DELAY_NIBBLE, delay_l => DELAY_1640_US));

signal this_op : op_t;

type op_state_t is (IDLE,
                      WAIT_SETUP_H,
                      ENABLE_H,
                      WAIT_HOLD_H,
                      WAIT_DELAY_H,
                      WAIT_SETUP_L,
                      ENABLE_L,
                      WAIT_HOLD_L,
                      WAIT_DELAY_L,
                      DONE);

signal op_state      : op_state_t := DONE;
  signal next_op_state : op_state_t;
  signal cnt           : natural range 0 to MAX_DELAY;
  signal next_cnt      : natural range 0 to MAX_DELAY;

type state_t is (RESET,
                   CONFIG,
                   SELECT_LINE1,
                   WRITE_LINE1,
                   SELECT_LINE2,
                   WRITE_LINE2);

signal state      : state_t               := RESET;
  signal next_state : state_t;
  signal ptr        : natural range 0 to 15 := 0;
  signal next_ptr   : natural range 0 to 15;

begin

proc_state : process(state, op_state, ptr, line1_buffer, line2_buffer) is
  begin
    case state is
      when RESET =>
        this_op    <= default_op;
        next_state <= CONFIG;
        next_ptr   <= config_ops_t'high;
      
      when CONFIG =>
        this_op    <= config_ops(ptr);
        next_ptr   <= ptr;
        next_state <= CONFIG;
        if op_state = DONE then
          next_ptr <= ptr - 1;
          if ptr = 0 then
            next_state <= SELECT_LINE1;
          end if;
        end if;

when SELECT_LINE1 =>
        this_op  <= op_select_line1;
        next_ptr <= 15;
        if op_state = DONE then
          next_state <= WRITE_LINE1;
        else
          next_state <= SELECT_LINE1;
        end if;

when WRITE_LINE1 =>
        this_op      <= default_op;
        this_op.data <= line1_buffer(ptr*8 + 7 downto ptr*8);
        next_ptr     <= ptr;
        next_state   <= WRITE_LINE1;
        if op_state = DONE then
          next_ptr <= ptr - 1;
          if ptr = 0 then
            next_state <= SELECT_LINE2;
          end if;
        end if;

when SELECT_LINE2 =>
        this_op  <= op_select_line2;
        next_ptr <= 15;
        if op_state = DONE then
          next_state <= WRITE_LINE2;
        else
          next_state <= SELECT_LINE2;
        end if;

when WRITE_LINE2 =>
        this_op      <= default_op;
        this_op.data <= line2_buffer(ptr*8 + 7 downto ptr*8);
        next_ptr     <= ptr;
        next_state   <= WRITE_LINE2;
        if op_state = DONE then
          next_ptr <= ptr - 1;
          if ptr = 0 then
            next_state <= SELECT_LINE1;
          end if;
        end if;
      
    end case;
  end process proc_state;

reg_state : process(clk)
  begin
    if rising_edge(clk) then
      if rst = '1' then
        state <= RESET;
        ptr   <= 0;
      else
        state <= next_state;
        ptr   <= next_ptr;
      end if;
    end if;
  end process reg_state;

lcd_rw <= '0';

proc_op_state : process(op_state, cnt, this_op) is
  begin
    case op_state is
      when IDLE =>
        lcd_db        <= (others => '0');
        lcd_rs        <= '0';
        lcd_e         <= '0';
        next_op_state <= WAIT_SETUP_H;
        next_cnt      <= DELAY_SETUP_HOLD;
      
      when WAIT_SETUP_H =>
        lcd_db <= this_op.data(7 downto 4);
        lcd_rs <= this_op.rs;
        lcd_e  <= '0';
        if cnt = 0 then
          next_op_state <= ENABLE_H;
          next_cnt      <= DELAY_LCD_E;
        else
          next_op_state <= WAIT_SETUP_H;
          next_cnt      <= cnt - 1;
        end if;

when ENABLE_H =>
        lcd_db <= this_op.data(7 downto 4);
        lcd_rs <= this_op.rs;
        lcd_e  <= '1';
        if cnt = 0 then
          next_op_state <= WAIT_HOLD_H;
          next_cnt      <= DELAY_SETUP_HOLD;
        else
          next_op_state <= ENABLE_H;
          next_cnt      <= cnt - 1;
        end if;

when WAIT_HOLD_H =>
        lcd_db <= this_op.data(7 downto 4);
        lcd_rs <= this_op.rs;
        lcd_e  <= '0';
        if cnt = 0 then
          next_op_state <= WAIT_DELAY_H;
          next_cnt      <= this_op.delay_h;
        else
          next_op_state <= WAIT_HOLD_H;
          next_cnt      <= cnt - 1;
        end if;

when WAIT_DELAY_H =>
        lcd_db <= (others => '0');
        lcd_rs <= '0';
        lcd_e  <= '0';
        if cnt = 0 then
          next_op_state <= WAIT_SETUP_L;
          next_cnt      <= DELAY_SETUP_HOLD;
        else
          next_op_state <= WAIT_DELAY_H;
          next_cnt      <= cnt - 1;
        end if;

when WAIT_SETUP_L =>
        lcd_db <= this_op.data(3 downto 0);
        lcd_rs <= this_op.rs;
        lcd_e  <= '0';
        if cnt = 0 then
          next_op_state <= ENABLE_L;
          next_cnt      <= DELAY_LCD_E;
        else
          next_op_state <= WAIT_SETUP_L;
          next_cnt      <= cnt - 1;
        end if;

when ENABLE_L =>
        lcd_db <= this_op.data(3 downto 0);
        lcd_rs <= this_op.rs;
        lcd_e  <= '1';
        if cnt = 0 then
          next_op_state <= WAIT_HOLD_L;
          next_cnt      <= DELAY_SETUP_HOLD;
        else
          next_op_state <= ENABLE_L;
          next_cnt      <= cnt - 1;
        end if;

when WAIT_HOLD_L =>
        lcd_db <= this_op.data(3 downto 0);
        lcd_rs <= this_op.rs;
        lcd_e  <= '0';
        if cnt = 0 then
          next_op_state <= WAIT_DELAY_L;
          next_cnt      <= this_op.delay_l;
        else
          next_op_state <= WAIT_HOLD_L;
          next_cnt      <= cnt - 1;
        end if;

when WAIT_DELAY_L =>
        lcd_db <= (others => '0');
        lcd_rs <= '0';
        lcd_e  <= '0';
        if cnt = 0 then
          next_op_state <= DONE;
          next_cnt      <= 0;
        else
          next_op_state <= WAIT_DELAY_L;
          next_cnt      <= cnt - 1;
        end if;

when DONE =>
        lcd_db        <= (others => '0');
        lcd_rs        <= '0';
        lcd_e         <= '0';
        next_op_state <= IDLE;
        next_cnt      <= 0;
      
    end case;
  end process proc_op_state;

reg_op_state : process (clk) is
  begin
    if rising_edge(clk) then
      if state = RESET then
        op_state <= IDLE;
      else
        op_state <= next_op_state;
        cnt      <= next_cnt;
      end if;
    end if;
  end process reg_op_state;
end architecture rtl;

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