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Writing a variable on LCD Screen

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vitruvius

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Hi all. I'm begginer at both Fpga and Vhdl and i have got Spartan-3E Starter Kit. I can write every character i want. For example, the character "R" from the CG-ROM have the value "01010010". I send this data like this:

Code: 
DATA<=X"52"; --R
            when 193=>
                DB<=DATA(7 downto 4);
            when 194=>LCD_E<='1';			
            when 195=>LCD_E<='0';
            when 196=>DB<=DATA(3 downto 0);
            when 197=>LCD_E<='1';
            when 198=>LCD_E<='0';

But how can i write a variable on lcd screen? I have a variable (cnt: integer range 0 to 8) which counts up each time i press the button. I want to see this on the lcd screen.

This is what i use for counter: (I can see the value of the integer by using leds)
Code: 
architecture Behavioral of debounce is

signal counter : integer range 0 to 15000000;
signal buton_b : std_logic;
signal buton_g : std_logic;
signal cnt : integer range 0 to 8;
signal ledg : std_logic_vector(7 downto 0);



begin
	led <= ledg;

	process(clk) -- Debounce
    begin
        if(clk'event and clk='1') then
            if(buton_b <= '1') then
            counter<=counter+1;
            buton_g<='0';
            elsif(buton='1') then
            buton_b<='1';
            end if;
                if(counter=15000000) then --300ms
                counter<=0;
                buton_b<='0';
                    if(buton='1') then
                    buton_g<='1';
                    end if;
                end if;
        end if;
    end process;
    
    process(clk) --Cnt
    begin
		if(clk'event and clk='1') then
			if(buton_g='1') then
			cnt<=cntc+1;
					if(cnt=8) then
					cnt<=0;
					end if;
			end if;
		end if;
    end process;
    
    process(cnt)
    begin
        case cnt is
            when 0 => ledg <= "00000000";
            when 1 => ledg <= "00000001";
            when 2 => ledg <= "00000010";
            when 3 => ledg <= "00000100";
            when 4 => ledg <= "00001000";
            when 5 => ledg <= "00010000";
            when 6 => ledg <= "00100000";
            when 7 => ledg <= "01000000";				
            when others => ledg <= "10000000";
        end case;
   end process;

Thank you.
 

When i tried like this:

Code: 
DATA<=(conv_std_logic_vector((cnt),8));

i see a character looks like || and it doesn't change when i press the button.
 

u have to convert the integer to ascii..

and this is how u can convert a number of the range 0-9

Code: 
int i;
......

...
lcd_write_byte(i+48);
 

I tried this:
Code: 
DATA<=(conv_std_logic_vector((cnt+48),8));

But this time, i just see a "0" and it doesn't change when i press the button.
 

if its so then it means that your index numb cnt is not incrementing ... its zero even if u press the key .. check your code
 

But this part works correctly.

Code: 
process(cnt)
    begin
        case cnt is
            when 0 => ledg <= "00000000";
            when 1 => ledg <= "00000001";
            when 2 => ledg <= "00000010";
            when 3 => ledg <= "00000100";
            when 4 => ledg <= "00001000";
            when 5 => ledg <= "00010000";
            when 6 => ledg <= "00100000";
            when 7 => ledg <= "01000000";				
            when others => ledg <= "10000000";
        end case;
   end process;

I mean i can see the value of the "cnt" on leds.
 

ok ! do you mean that LEDs show the correct values?

then try this . instead of
Code: 
DATA<=(conv_std_logic_vector((cnt+48),8));

so this
Code: 
cnt=cnt+48;
DATA<=(conv_std_logic_vector((cnt),8));

try this way!
 

It still doesn't work.

My entire code:

Code: 
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;

entity tplcdvebuton is
port (
		 buton : in std_logic;
		 led : out std_logic_vector(7 downto 0);
		 clk : in std_logic;		 
		 DB : out  STD_LOGIC_VECTOR (7 downto 4); 
       LCD_E :out STD_LOGIC;
       LCD_RS :out STD_LOGIC;
       LCD_RW :out STD_LOGIC
);
end tplcdvebuton;

architecture Behavioral of tplcdvebuton is
--------------- Signals for Button and Debounce ----------------
signal counter : integer range 0 to 15000000;
signal buton_b : std_logic;
signal buton_g : std_logic;
signal cnt : integer range 0 to 8;
signal ledg : std_logic_vector(7 downto 0);
-----------------------------------------------------------------------------

--------------- Signals for Lcd ------------------------------
Signal StopTimer:std_logic;
Signal DATA : STD_LOGIC_VECTOR (7 downto 0);
-----------------------------------------------------------------------------

begin
	led <= ledg;

	process(clk) -- Debounce
    begin
        if(clk'event and clk='1') then
            if(buton_b <= '1') then
            counter<=counter+1;
            buton_g<='0';
            elsif(buton='1') then
            buton_b<='1';
            end if;
                if(counter=15000000) then --300ms
                counter<=0;
                buton_b<='0';
                    if(buton='1') then
                    buton_g<='1';
                    end if;
                end if;
        end if;
    end process;
    
    process(clk) --Cnt
    begin
		if(clk'event and clk='1') then
			if(buton_g='1') then
			cnt<=cnt+1;
					if(cnt=8) then
					cnt<=0;
					end if;
			end if;
		end if;
    end process;
    
    process(cnt) -- Checking the value of cnt with using LEDs
    begin
        case cnt is
            when 0 => ledg <= "00000000";
            when 1 => ledg <= "00000001";
            when 2 => ledg <= "00000010";
            when 3 => ledg <= "00000100";
            when 4 => ledg <= "00001000";
            when 5 => ledg <= "00010000";
            when 6 => ledg <= "00100000";
            when 7 => ledg <= "01000000";				
            when others => ledg <= "10000000";
        end case;
   end process;
	
	------------------------------------- LCD ------------------------------------
	process (clk)
    variable say1:integer;
    variable say2:integer;
    begin
    if (clk'EVENT and clk='1') then
    if (StopTimer='0') then 
    say1:=say1+1;
    end if;				
        if (say1>50000) then	--1 KHZ
        say1:=0;
        say2:=say2+1;
            case say2 is
            when 90=>
                LCD_RW<='0';
                LCD_RS<='0'; --CMD
                DB<="0011";
            when 99=>LCD_E<='1';
            when 100=>LCD_E<='0';
            when 115=>LCD_E<='1';
            when 116=>LCD_E<='0';
            when 121=>LCD_E<='1';
            when 122=>LCD_E<='0';
            when 127=>DB<="0010";
            when 128=>LCD_E<='1';
            when 129=>LCD_E<='0';

            
            when 149=>DATA<=X"28";
            when 150=>DB<=DATA(7 downto 4);
            when 151=>LCD_E<='1';			
            when 152=>LCD_E<='0';
            when 153=>DB<=DATA(3 downto 0);
            when 154=>LCD_E<='1';
            when 155=>LCD_E<='0';			
            DATA<=X"08";

            when 156=>DB<=DATA(7 downto 4);
            when 157=>LCD_E<='1';			
            when 158=>LCD_E<='0';
            when 159=>DB<=DATA(3 downto 0);
            when 160=>LCD_E<='1';
            when 161=>LCD_E<='0';				
                DATA<=X"01"; 
            when 162=>
                DB<=DATA(7 downto 4);
            when 163=>LCD_E<='1';			
            when 164=>LCD_E<='0';
            when 165=>DB<=DATA(3 downto 0);
            when 166=>LCD_E<='1';
            when 167=>LCD_E<='0';	
                DATA<=X"06";
            when 168=>
                DB<=DATA(7 downto 4);
            when 169=>LCD_E<='1';			
            when 170=>LCD_E<='0';
            when 171=>DB<=DATA(3 downto 0);
            when 172=>LCD_E<='1';
            when 173=>LCD_E<='0';
                DATA<=X"0C";
            when 174=>
                DB<=DATA(7 downto 4);
            when 175=>LCD_E<='1';			
            when 176=>LCD_E<='0';
            when 177=>DB<=DATA(3 downto 0);
            when 178=>LCD_E<='1';
            when 179=>LCD_E<='0';			
            
            when 180=>LCD_RS<='1'; --Chr
                DATA<=X"43"; -- C
            when 181=>
                DB<=DATA(7 downto 4);
            when 182=>LCD_E<='1';			
            when 183=>LCD_E<='0';
            when 184=>DB<=DATA(3 downto 0);
            when 185=>LCD_E<='1';
            when 186=>LCD_E<='0';	
				
                DATA<=X"4E"; -- N
            when 187=>
                DB<=DATA(7 downto 4);
            when 188=>LCD_E<='1';			
            when 189=>LCD_E<='0';
            when 190=>DB<=DATA(3 downto 0);
            when 191=>LCD_E<='1';
            when 192=>LCD_E<='0';	
				
                DATA<=X"54"; -- T
            when 193=>
                DB<=DATA(7 downto 4);
            when 194=>LCD_E<='1';			
            when 195=>LCD_E<='0';
            when 196=>DB<=DATA(3 downto 0);
            when 197=>LCD_E<='1';
            when 198=>LCD_E<='0';
				
                DATA<=X"3D"; -- =
            when 199=>
                DB<=DATA(7 downto 4);
            when 200=>LCD_E<='1';			
            when 201=>LCD_E<='0';
            when 202=>DB<=DATA(3 downto 0);
            when 203=>LCD_E<='1';
            when 204=>LCD_E<='0';
				
                DATA<=(conv_std_logic_vector((cnt+48),8));
            when 205=>
                DB<=DATA(7 downto 4);
            when 206=>LCD_E<='1';			
            when 207=>LCD_E<='0';
            when 208=>DB<=DATA(3 downto 0);
            when 209=>LCD_E<='1';
            when 210=>LCD_E<='0';                
            
            when 3000=> --StopTimer <='1';
            when others=>
            end case;
        
        end if;
    end if;
    end process;

end Behavioral;
 

which compiler are u using??

by the way try this instead of starting your cnt as 0 start it with value 3 and the check .. you would get 3 all the time with DATA<=(conv_std_logic_vector((cnt+48),8));
 

I'm using Xilinx ISE Design Suite 13.3.

I've changed this part
Code: 
signal cnt : integer range 0 to 8 :=3;

And i get "CNT=3" all the time, it doesn't change when i press the button.
 

so the problem is in the code where you update the value of CNT. I havent used this Xilinx ISE Design Suite so I cant tell u the exact solution but check your syntax, there might be a problem , or may bethere is a problem with the logic you are following .

the root cause is your value of CNT doesnt change in the program!
 

I think the problem is with the StopTimer signal. My lcd process starts with:

Code: 
begin
    if (clk'EVENT and clk='1') then
    if (StopTimer='0') then

But "StopTimer" never changes..
 

i dont know about the syntax of your ide but in c comparisons are == and if u declare int i='0' then its value is ASCII value of the number zero
 

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