diff --git a/lcd_driver.vhd b/lcd_driver.vhd
index 0c3f48c..9550d3e 100644
--- a/lcd_driver.vhd
+++ b/lcd_driver.vhd
@@ -25,8 +25,6 @@
--
-- Dependencies:
--
--- Revision:
--- Revision 0.01 - File Created
-- Additional Comments:
--
----------------------------------------------------------------------------------
@@ -50,60 +48,56 @@ entity lcd_driver is
wait_between : natural := 37; -- wait 37us
wait_pause : natural := 1520); -- wait 1.52ms
- Port ( clk : in STD_LOGIC; -- Systemclock (50MHz)
- reset : in STD_LOGIC; -- Initialize display controller
- data : in STD_LOGIC_VECTOR (7 downto 0); -- either one ascii char (8bit) or new cursor position (0-31)
- new_character : in STD_LOGIC; -- a new character is available on the data bus
- new_pos : in STD_LOGIC; -- a new cursor position is available on the data bus
- auto_incr_cursor : in STD_LOGIC; -- the cursor should automatically be incremented after writing a new character
- lcd_db : out STD_LOGIC_VECTOR (7 downto 0); -- lcd databus
- lcd_en : out STD_LOGIC; -- lcd enable
- lcd_rw : out STD_LOGIC; -- lcd read/write
- lcd_rs : out STD_LOGIC); -- lcd register select
+ Port ( clk : in STD_LOGIC; -- Systemclock (50MHz)
+ reset : in STD_LOGIC; -- Initialize display controller
+ data : in STD_LOGIC_VECTOR (7 downto 0); -- either one ascii char (8bit) or new cursor position (0-31)
+ new_character : in STD_LOGIC; -- a new character is available on the data bus
+ new_pos : in STD_LOGIC; -- a new cursor position is available on the data bus
+ auto_incr_cursor : in STD_LOGIC; -- the cursor should automatically be incremented after writing a new character
+ busy : out STD_LOGIC; -- 1 when sending stuff
+ lcd_db : out STD_LOGIC_VECTOR (7 downto 0); -- lcd databus
+ lcd_en : out STD_LOGIC; -- lcd enable
+ lcd_rs : out STD_LOGIC); -- lcd register select
end lcd_driver;
architecture Behavioral of lcd_driver is
-- type definitions
type display_state is (
- INIT, -- initialization, wait for 40ms to pass
- SEND_FS1, -- send the function set
- SEND_FS2, -- send the function set
- SEND_SD, -- send the display ON/OFF control
- SEND_CD, -- send a clear
- SEND_ES, -- send entry mode set
- WAITING1, -- wait and toggle lcd_en
- WAITING2, -- wait and toggle lcd_en
- WAITING3, -- wait and toggle lcd_en
- DONE); -- initialization done
+ INIT, -- initialization, wait for 40ms to pass
+ SEND_FS1, -- send the function set
+ SEND_FS2, -- send the function set
+ SEND_SD, -- send the display ON/OFF control
+ SEND_CD, -- send a clear
+ SEND_ES, -- send entry mode set
+ WAITING1, -- wait and toggle lcd_en
+ WAITING2, -- wait and toggle lcd_en
+ WAITING3, -- wait and toggle lcd_en
+ DONE); -- initialization done
-- signals
- signal init_done : STD_LOGIC := '0'; -- 1 when initialization done, else 0
+ signal cur_state : display_state := INIT; -- cur_state register
+ signal next_state : display_state := INIT; -- next_state register
+ signal ret_state : display_state := INIT; -- ret_state register
+ signal next_ret_state : display_state := INIT; -- next_ret_state register
- signal cur_state : display_state := INIT; -- cur_state register
- signal next_state : display_state := INIT; -- next_state register
- signal ret_state : display_state := INIT; -- ret_state register
- signal next_ret_state : display_state := INIT; -- next_ret_state register
-
- signal cur_counter : unsigned(NBITS-1 downto 0) := (others => '0'); -- n bit counter signal
- signal next_counter : unsigned(NBITS-1 downto 0) := (others => '0');
- signal ret_counter : unsigned(NBITS-1 downto 0) := (others => '0'); -- n bit counter signal
+ signal cur_counter : unsigned(NBITS-1 downto 0) := (others => '0'); -- current counter
+ signal next_counter : unsigned(NBITS-1 downto 0) := (others => '0'); -- next current counter
+ signal ret_counter : unsigned(NBITS-1 downto 0) := (others => '0'); -- return current counter
signal next_ret_counter : unsigned(NBITS-1 downto 0) := (others => '0');
- signal next_lcd_db : STD_LOGIC_VECTOR(7 downto 0) := (others => '0'); -- next lcd databus
- signal next_lcd_en : STD_LOGIC := '0'; -- next lcd enable
- signal next_lcd_rw : STD_LOGIC := '0'; -- next lcd read/write
- signal next_lcd_rs : STD_LOGIC := '0'; -- next lcd register select
+ signal next_lcd_db : STD_LOGIC_VECTOR(7 downto 0) := (others => '0'); -- next lcd databus
+ signal next_lcd_en : STD_LOGIC := '0'; -- next lcd enable
+ signal next_lcd_rs : STD_LOGIC := '0'; -- next lcd register select
- signal cur_lcd_db : STD_LOGIC_VECTOR(7 downto 0) := (others => '0'); -- next lcd databus
- signal cur_lcd_en : STD_LOGIC := '0'; -- next lcd enable
- signal cur_lcd_rw : STD_LOGIC := '0'; -- next lcd read/write
- signal cur_lcd_rs : STD_LOGIC := '0'; -- next lcd register select
+ signal cur_lcd_db : STD_LOGIC_VECTOR(7 downto 0) := (others => '0'); -- next lcd databus
+ signal cur_lcd_en : STD_LOGIC := '0'; -- next lcd enable
+ signal cur_lcd_rs : STD_LOGIC := '0'; -- next lcd register select
-- constants
- constant INIT_COUNT : natural := clk_freq / (1000000 / wait_init); -- number of clock cycles for 40ms
- constant PAUSE_COUNT : natural := clk_freq / (1000000 / wait_between); -- number of clock cycles for 37us
- constant CLEAR_DISPLAY_COUNT : natural := clk_freq / (1000000 / wait_pause); -- number of clock cycles for 1.52ms
+ constant INIT_COUNT : natural := clk_freq / (1000000 / wait_init); -- number of clock cycles for 40ms
+ constant PAUSE_COUNT : natural := clk_freq / (1000000 / wait_between); -- number of clock cycles for 37us
+ constant CLEAR_DISPLAY_COUNT : natural := clk_freq / (1000000 / wait_pause); -- number of clock cycles for 1.52ms
begin
@@ -120,7 +114,6 @@ begin
ret_counter <= (others => '0');
cur_lcd_db <= (others => '0');
cur_lcd_en <= '0';
- cur_lcd_rw <= '0';
cur_lcd_rs <= '0';
elsif rising_edge(clk) then -- synchronous on clk
cur_state <= next_state;
@@ -129,7 +122,6 @@ begin
ret_counter <= next_ret_counter;
cur_lcd_db <= next_lcd_db;
cur_lcd_en <= next_lcd_en;
- cur_lcd_rw <= next_lcd_rw;
cur_lcd_rs <= next_lcd_rs;
end if;
end process REGS;
@@ -138,24 +130,23 @@ begin
-- type : sequential
-- inputs : clk, cur_state
-- outputs : none
- NSL: process(clk, cur_state, cur_counter, cur_lcd_db, cur_lcd_en, cur_lcd_rw, cur_lcd_rs, ret_state, ret_counter) is
+ NSL: process(clk, cur_state, cur_counter, cur_lcd_db, cur_lcd_en, cur_lcd_rs, ret_state, ret_counter) is
begin
- next_state <= cur_state; -- state stays the same
next_counter <= cur_counter + 1; -- increment counter
+
+ next_state <= cur_state;
next_lcd_db <= cur_lcd_db;
next_lcd_en <= cur_lcd_en;
- next_lcd_rw <= cur_lcd_rw;
next_lcd_rs <= cur_lcd_rs;
next_ret_state <= ret_state;
next_ret_counter <= ret_counter;
- case cur_state is -- switch on current state
- when INIT =>
+ case cur_state is
+ when INIT => -- switch on current state
next_lcd_db <= "00000000";
next_lcd_en <= '0';
- next_lcd_rw <= '0';
next_lcd_rs <= '0';
next_counter <= (others => '0');
@@ -163,11 +154,10 @@ begin
next_ret_counter <= to_unsigned(INIT_COUNT, NBITS);
next_state <= WAITING2;
- when SEND_FS1 =>
+ when SEND_FS1 => -- first function set
next_lcd_db <= "00111000";
next_lcd_en <= '1';
- next_lcd_rw <= '0';
next_lcd_rs <= '0';
next_counter <= (others => '0');
@@ -175,11 +165,10 @@ begin
next_ret_counter <= to_unsigned(PAUSE_COUNT, NBITS);
next_state <= WAITING1;
- when SEND_FS2 =>
+ when SEND_FS2 => -- second function set
next_lcd_db <= "00111000";
next_lcd_en <= '1';
- next_lcd_rw <= '0';
next_lcd_rs <= '0';
next_counter <= (others => '0');
@@ -187,11 +176,10 @@ begin
next_ret_counter <= to_unsigned(PAUSE_COUNT,NBITS);
next_state <= WAITING1;
- when SEND_SD =>
+ when SEND_SD => -- display ON/OFF setting
next_lcd_db <= "00001111";
next_lcd_en <= '1';
- next_lcd_rw <= '0';
next_lcd_rs <= '0';
next_counter <= (others => '0');
@@ -199,11 +187,10 @@ begin
next_ret_counter <= to_unsigned(PAUSE_COUNT,NBITS);
next_state <= WAITING1;
- when SEND_CD =>
+ when SEND_CD => -- clear display
next_lcd_db <= "00000001";
next_lcd_en <= '1';
- next_lcd_rw <= '0';
next_lcd_rs <= '0';
next_counter <= (others => '0');
@@ -211,11 +198,10 @@ begin
next_ret_counter <= to_unsigned(CLEAR_DISPLAY_COUNT,NBITS);
next_state <= WAITING3;
- when SEND_ES =>
+ when SEND_ES => -- entry set mode
next_lcd_db <= "00000110";
next_lcd_en <= '1';
- next_lcd_rw <= '0';
next_lcd_rs <= '0';
next_counter <= (others => '0');
@@ -223,15 +209,21 @@ begin
next_ret_counter <= to_unsigned(PAUSE_COUNT,NBITS);
next_state <= WAITING1;
- when DONE =>
+ when DONE => -- initialization done
next_lcd_db <= "00000000";
next_lcd_en <= '1';
- next_lcd_rw <= '0';
next_lcd_rs <= '0';
- init_done <= '1';
+
+ if(new_character == '1') then -- send data
+ next_counter <= (others => '0');
+ next_ret_state <= DONE;
+ next_ret_counter <= to_unsigned(PAUSE_COUNT,NBITS);
+ next_state <= WAITING1;
+ next_lcd_db <= data;
+ end if;
- when WAITING1 =>
+ when WAITING1 => -- wait with jump
if(cur_counter >= ret_counter) then
next_state <= WAITING2;
@@ -241,7 +233,7 @@ begin
next_lcd_en <= '1';
- when WAITING2 =>
+ when WAITING2 => -- wait without jump
if(cur_counter >= ret_counter) then
next_state <= ret_state;
@@ -249,7 +241,7 @@ begin
next_lcd_en <= '0';
- when WAITING3 =>
+ when WAITING3 => -- wait with counter reset
if(cur_counter >= PAUSE_COUNT) then
next_state <= WAITING2;
@@ -264,8 +256,7 @@ begin
-- Output logic
lcd_db <= cur_lcd_db;
lcd_en <= cur_lcd_en;
- lcd_rw <= cur_lcd_rw;
lcd_rs <= cur_lcd_rs;
+ busy <= '0' when cur_state == DONE else '1';
-end Behavioral;
-
+end Behavioral;
\ No newline at end of file
diff --git a/yasg.gise b/yasg.gise
index e01d8aa..edda31c 100644
--- a/yasg.gise
+++ b/yasg.gise
@@ -258,7 +258,9 @@
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