# Homework Help: Hexadecimal number on seven-segment

1. Oct 6, 2011

### dawnoflife

I need to design a bank of four 4-bit registers whose contents are displayed on the seven-segment displays. So, basically just display 4 hexadecimal numbers on the 7-segment. The output switches on its own with every clock cycle. I'm using a Basys2 board for this. This is what I have so far...

Code (Text):
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity Register_Bank is
port( x: in std_logic_vector(3 downto 0);
disp_en: out std_logic_vector(3 downto 0);
z:  out std_logic_vector(7 downto 0);
ck,reset: in std_logic);
end Register_Bank;

architecture Behavioral of Register_Bank is

Type my_state is(s0,s1,s2,s3);
Signal n_s: my_state;
Signal ck_div: std_logic;
Signal temp,temp1,temp2,temp3,temp0,temp_main: std_logic_vector(0 to 3);
Signal R0,R1,R2,R3 : std_logic_vector(3 downto 0);

begin

--
process(temp_main)
begin
case temp_main is
when "0000" => z <= "00000011";
when "0001" => z <= "10011111";
when "0010" => z <= "00100101";
when "0011" => z <= "00001101";
when "0100" => z <= "10011001";
when "0101" => z <= "01001001";
when "0110" => z <= "01000001";
when "0111" => z <= "00011111";
when "1000" => z <= "00000001";
when "1001" => z <= "00001001";
when "1010" => z <= "00010001";
when "1011" => z <= "11000001";
when "1100" => z <= "01100011";
when "1101" => z <= "10000101";
when "1110" => z <= "01100001";
when "1111" => z <= "01110001";
when others => null;

--temp3 <= x<3>;
--temp2 <= x<2>;
--temp1 <= x<1>;
--temp0 <= x<0>;

--wiring the register contents to outputs
temp3 <= R3;
temp2 <= R2;
temp1 <= R1;
temp0 <= R0;

--state machine for TMD
Process(x,ck_div)
begin
if ck_div ='1' and ck_div'event then
case n_s is
when s0 =>
temp <= x<0>;
disp_en <= "0111";
n_s <= s1;
when s1 =>
temp <= x<1>;
disp_en <= "1011";
n_s <= s2;
when s2 =>
temp <= x<2>;
disp_en <= "1101";
n_s <= s3;
when s3 =>
temp <= x<3>;
disp_en <= "1110";
n_s <= s0;
end case;
end if;
end process;

-- clock division
process(ck)
variable count: integer;
begin
if ck ='1' and ck'event then
if reset ='1' then
count := 0;
ck_div <= '0';
elsif reset ='0' then
if count = 999999 then
ck_div <= not ck_div;
count := 0;
else
count := count + 1;
end if;
end if;
end if;
end process;

end Behavioral;

I know the logic is off and there are syntactical errors as well. I need help trying to debug this. I'd greatly appreciate help!
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution