Implementing a simple counter using VHDL

Question

Hi I'm trying to implement a counter with external control. I'm kinda new to VHDL and I keep getting syntax error for the following code. Can someone help me understand why there's an error here?

library IEEE;
use IEEE.STD_LOGIC_1164.ALL;

entity lab5 is
    Port ( Abbreviate : in  STD_LOGIC;
           Halt : in  STD_LOGIC;
           clk : in  STD_LOGIC;
              LED_left : out STD_LOGIC_VECTOR(7 downto 0);
              LED_right : out STD_LOGIC_VECTOR(7 downto 0));
end lab5;

architecture Behavioral of lab5 is
type State_type is (two, three, one, six, zero, seven);
signal state : State_type;
signal state_right : State_type;
signal first_time : integer := 1;
state <= two;
state_right <= six;
begin
process(clk)
        begin 
        if (rising_edge(Abbreviate)) then
        first_time <= '1';
        end if;
        if(rising_edge(clk)) then
        case state is
        when two =>

        if (Halt = '1') then
        state <= two;
        LED_left <= "1111001";
        else
        state <= three;
        LED_left <= "1101101";
        end if;
        when three =>

        if (Halt = '1') then
        state <= three;
        LED_left <= "1101101";
        else
        state <= one;
        LED_left <= "0100100";
        end if;
        when one =>

        if (Halt = '1') then
        state <= one;
        LED_left <= "0100100";
        else
        state <= six;
        LED_left <= "1011111";
        end if;

        when six =>

        if (Halt = '1') then
        state <= six;
        LED_left <= "1011111";
        else
        state <= zero;
        LED_left <= "1111110";
        end if;

        when zero =>

        if (Halt = '1') then
        state <= zero;
        LED_left <= "1111110";
        else
        state <= two;
        LED_left <= "1111001";
        end if;
        end case
        end if;

        case state_right is
        when six
        if (Abbreviate = '1') then
        if (first_time = '1') then
        if (state = two) then
        state_right <= six;
        LED_right <='1011111';
        first_time <= '0';
        end if;
        else
        state_right <= seven;
        LED_right <='1100100';
        end if;
        else
        state_right <= six;
        LED_right <= '1011111';
        end if

        when seven
        state_right <= six
        LED_right <= '1011111';
        end if 
        end process

end Behavioral;

The errors are at line 45 and it says syntax error near "state" and line 103 which says syntax error near "end"

Thank you in advance for helping out.

Answer 1

I have just corrected your syntax errors. From design point of view in a synchronous process you must have just one member in the sensitivity list. (here its name is CLK) remember that you are not allowed to use risingedge for a signal that is not in the sensitivity list and it is not a good practice to have more than one clock pulse signal in a process. It is the corrected code:

    library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
entity lab5 is
    Port ( Abbreviate : in  STD_LOGIC;
           Halt : in  STD_LOGIC;
           clk : in  STD_LOGIC;
           LED_left : out STD_LOGIC_VECTOR(6 downto 0);
           LED_right : out STD_LOGIC_VECTOR(6 downto 0));
end lab5;
architecture Behavioral of lab5 is
type State_type is (two, three, one, six, zero, seven);
signal state : State_type := two;
signal state_right : State_type := six;
signal first_time : integer := 1;
begin
process(clk)
begin 
  if (rising_edge(clk)) then
     if Abbreviate ='1' then
        first_time <= 1;
     end if;
  end if;
  if(rising_edge(clk)) then
      case state is
        when two =>

        if (Halt = '1') then
          state <= two;
          LED_left <= "1111001";
        else
          state <= three;
          LED_left <= "1101101";
        end if;
        when three =>

        if (Halt = '1') then
          state <= three;
          LED_left <= "1101101";
        else
          state <= one;
          LED_left <= "0100100";
        end if;
        when one =>

        if (Halt = '1') then
          state <= one;
          LED_left <= "0100100";
        else
          state <= six;
          LED_left <= "1011111";
        end if;

        when six =>

        if (Halt = '1') then
          state <= six;
          LED_left <= "1011111";
        else
          state <= zero;
          LED_left <= "1111110";
        end if;

        when zero =>

        if (Halt = '1') then
          state <= zero;
          LED_left <= "1111110";
        else
          state <= two;
          LED_left <= "1111001";
        end if;
        when others => null;
      end case;

      case state_right is
        when six =>
        if Abbreviate ='1' then
          if (first_time = 1) then
            if (state = two) then
              state_right <= six;
              LED_right <= "1011111";
              first_time <= 0;
            end if;
          else
            state_right <= seven;
            LED_right <= "1100100";
          end if;
        else
          state_right <= six;
          LED_right <= "1011111";
        end if;

        when seven =>
          state_right <= six;
          LED_right <= "1011111";
        when others => null;
      end case;
  end if;
end process;
end Behavioral;