[SOLVED] Need help for driving an 16x2 lcd

[gv260ea]

Couple of days ago i got an Xilinx Spartan 3E Starter board. I thought it would be a good board to start with FPGAS:grin:. I did couple of examples without copying the code as I want to learn vhdl and not to copy. Then i wanted to write the character H to the on board 16x2 lcd display. I screwed around for a whole day and. I got nothing:-?. Could someone figure out what's wrong with this code and what sould be fixed. Other than beeing untidy.
Here is the code. Thank you for helping me.

----------------------------------------------------------------------------------
-- Company: 
-- Engineer: 
-- 
-- Create Date:    11:00:06 06/27/2013 
-- Design Name: 
-- Module Name:    LCD - Behavioral 
-- Project Name: 
-- Target Devices: 
-- Tool versions: 
-- Description: 
--
-- Dependencies: 
--
-- Revision: 
-- Revision 0.01 - File Created
-- Additional Comments: 
--
----------------------------------------------------------------------------------
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
-- Uncomment the following library declaration if using
-- arithmetic functions with Signed or Unsigned values
--use IEEE.NUMERIC_STD.ALL;

-- Uncomment the following library declaration if instantiating
-- any Xilinx primitives in this code.
--library UNISIM;
--use UNISIM.VComponents.all;

entity LCDS is
	port(
	   CLK : in STD_LOGIC;
		LCD_E : out STD_LOGIC := '0';
		LCD_RS : out STD_LOGIC := '0';
		LCD_RW : out STD_LOGIC := '0';
		SF_D : out STD_LOGIC_VECTOR(11 downto 8) := "0000"
			);
end LCDS;

architecture Behavioral of LCDS is
	type Init is (W413, W2003, W43,W42,Done);
	type Conf is(FS40,EMS,DOF,DOF2,DOF3,Done);
	type LCD is (Writing,Ready);
	type PDelay is (US1,US200,MS5,none);
	type Chars is (H,Done);
	signal Chars_s : Chars := H;
	signal PDelay_s : PDelay := none ;
	signal Init_s : Init := W413 ;
	signal Conf_s : Conf := FS40 ;
	signal LCD_s : LCD := Writing ;
	signal Counter : STD_LOGIC_VECTOR(26 downto 0);
	signal PCounter : STD_LOGIC_VECTOR(1 downto 0);
	begin
		Display : Process (CLK)			
			begin
			if rising_edge(CLK) then
				if PDelay_s = none then
					Counter <= (others => '0');				
					if not(init_s = Done) then
						Case Init_s is
							when W413 =>
							LCD_RS <= '0';
							SF_D <= X"3";
							PDelay_s <= MS5;
							Init_s <= W2003;
							when W2003 =>
							SF_D <= "0000";
							PDelay_s <= US200;						
							Init_s <= W43;
							SF_D <= X"3";
							when W43 => 
							SF_D <= "0000";
							PDelay_s <= US200;						
							Init_s <= W42;
							SF_D <= X"3";
							when W42 =>
							SF_D <= "0000";
							PDelay_s <= US200;						
							Init_s <= Done;
							SF_D <= X"2";
							when others => NULL;
						End Case;		
					End if;
					if not(Conf_s = Done) then
						Case Conf_s is
							when FS40 => 		
							if PCounter = "00" then
							LCD_E <= '0';
							LCD_RS <= '0';
							SF_D <= X"8";
							LCD_E <= '1';
							PDelay_s <= US1;
							PCounter <= "01";
							elsif PCounter = "01"then
							LCD_E <= '0';
							PDelay_s <= MS5;
							PCounter <= "10";
							elsif PCounter = "10" then
							SF_D <= X"2";
							PDelay_s <= US1;
							PCounter <= "11";
							elsif PCounter = "11" then
							LCD_E <= '0';
							PCounter <= "00";
							PDelay_s <= MS5;
							Conf_s <= EMS;
							End if;
							when EMS =>
							if PCounter = "00" then
							LCD_E <= '0';
							LCD_RS <= '0';
							SF_D <= X"8";
							LCD_E <= '1';
							PDelay_s <= US1;
							PCounter <= "01";
							elsif PCounter = "01"then
							LCD_E <= '0';
							PDelay_s <= MS5;
							PCounter <= "10";
							elsif PCounter = "10" then
							SF_D <= X"0";
							PDelay_s <= US1;
							PCounter <= "11";
							elsif PCounter = "11" then
							LCD_E <= '0';
							PCounter <= "00";
							PDelay_s <= MS5;
							Conf_s <= DOF;
							End if;
							-------
							when DOF =>
							if PCounter = "00" then
							LCD_E <= '0';
							LCD_RS <= '0';
							SF_D <= X"1";
							LCD_E <= '1';
							PDelay_s <= US1;
							PCounter <= "01";
							elsif PCounter = "01"then
							LCD_E <= '0';
							PDelay_s <= MS5;
							PCounter <= "10";
							elsif PCounter = "10" then
							SF_D <= X"0";
							PDelay_s <= US1;
							PCounter <= "11";
							elsif PCounter = "11" then
							LCD_E <= '0';
							PCounter <= "00";
							PDelay_s <= MS5;
							Conf_s <= DOF2;
							End if;
							-----
							when DOF2 =>
							if PCounter = "00" then
							LCD_E <= '0';
							LCD_RS <= '0';
							SF_D <= X"6";
							LCD_E <= '1';
							PDelay_s <= US1;
							PCounter <= "01";
							elsif PCounter = "01"then
							LCD_E <= '0';
							PDelay_s <= MS5;
							PCounter <= "10";
							elsif PCounter = "10" then
							SF_D <= X"0";
							PDelay_s <= US1;
							PCounter <= "11";
							elsif PCounter = "11" then
							LCD_E <= '0';
							PCounter <= "00";
							PDelay_s <= MS5;
							Conf_s <= DOF3;
							End if;
							-------
							when DOF3 =>
							if PCounter = "00" then
							LCD_E <= '0';
							LCD_RS <= '0';
							SF_D <= X"C";
							LCD_E <= '1';
							PDelay_s <= US1;
							PCounter <= "01";
							elsif PCounter = "01"then
							LCD_E <= '0';
							PDelay_s <= MS5;
							PCounter <= "10";
							elsif PCounter = "10" then
							SF_D <= X"0";
							PDelay_s <= US1;
							PCounter <= "11";
							elsif PCounter = "11" then
							LCD_E <= '0';
							PCounter <= "00";
							PDelay_s <= MS5;
							Conf_s <= Done;
							End if;
							when others => NULL;							
							End Case; 
							End if;
						if LCD_s =  Writing then
						  Case Chars_s is
						   when H =>
							if PCounter = "00" then
							LCD_E <= '0';
							LCD_RS <= '0';
							SF_D <= X"3";
							LCD_E <= '1';
							PDelay_s <= US1;
							PCounter <= "01";
							elsif PCounter = "01"then
							LCD_E <= '0';
							PDelay_s <= US200;
							PCounter <= "10";
							elsif PCounter = "10" then
							SF_D <= X"2";
							PDelay_s <= US1;
							PCounter <= "11";
							elsif PCounter = "11" then
							LCD_E <= '0';
							PCounter <= "00";
							PDelay_s <= US200;
							LCD_s <= Ready;
							End if;
							When others => NULL;
							End Case;
							End if;
				 else
					Case PDelay_s is 
						When US1 =>
						 if Counter < "110010" then
							Counter <= Counter + 1;
						 else 
						 Counter <= (others => '0');
						  PDelay_s <= none;
						 End if;
						 When US200 =>
						 if Counter < "1111101000" then
							Counter <= Counter + 1;
						 else 
						 Counter <= (others => '0');
						  PDelay_s <= none;
						 End if;
						 When MS5 =>
						 if Counter < "111101000010010000" then
							Counter <= Counter + 1;
						 else 
						 Counter <= (others => '0');
						  PDelay_s <= none;
						 End if;
						 
						 
						 when others => NULL;
					 End Case;	 
				 End if;
			End if;
			
			
		End Process;
		LCD_RW <= '0';
end Behavioral;

 

[mrflibble]

A silly idea regarding a solution outside of the predefined box you have worked yourself into.

1 - add a simple MCU to the system
2 - use ChibiOS/GFX to handle all your hd44780 fun (it's bound to be a hd44780, right )
3 - implement a simple SPI statemachine to send high level commands to your mcu.
4 - profit
5 - stand amazed how easy that was, and how low the development cost of the working system is.
6 - goto 4

Personally I do exactly this with an stm32, but chibios is available for quite a few mcu's. Hell, if you insist on MUST HAVE FPGA ONLY! @_@ then you can also run it on a NIOS II softcore for example.

 

[gv260ea]

I know this sounds idiotic but i still need it my way as my misson is to learn vhdl.

 

[mrflibble]

Then you also should learn when to use HDL and when to use something else.

An lcd like that with a lot of relatively slow sequential control is a far better match to something like an mcu. Not that it's impossible to do in HDL, far from it. Just a poor allocation of resources (aka your development time).

But feel free to learn vhdl through a hammer shaped nail detector.

 

[gv260ea]

I noticed that the board also has a CoolRunner II Cpld. Should i use it for driving the lcd.

 

[mrflibble]

If you insist on using the fpga, then the next most sensible use of time is to use a microblaze or picoblaze core. That way you can program your lcd control in C or asm. And if you don't like that either, grab a piece of paper and start drawing that statemachine. If that is out as well I suggest a change of career. Strawberry farmer in a nice climate always appeals to me when I've had it with this electronics stuff.