counter help

[see-me]

i do my first programm in vhdl and i have a mistake and i dont know where it is..

i checked carefully all my work and i really dont know where am i wrong


please help me

library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_unsigned.all;
use ieee.numeric_std.all;

entity counter is
  generic(G_DATA_WIDTH : integer := 8);
  port(clk,reset, load : in std_logic;
	   opcode : in std_logic_vector (1 downto 0);
       data_in : in std_logic_vector(G_DATA_WIDTH-1 downto 0);
       cnt : out std_logic_vector(G_DATA_WIDTH-1 downto 0));
end counter;

architecture arc_counter of counter is
  SIGNAL temp1:   integer;
  signal ZEROS:  std_logic_vector(G_DATA_WIDTH-1 downto 0);
  signal ONES:   std_logic_vector(G_DATA_WIDTH-1 downto 0);
  
  
  
  

begin
  process(reset,clk)
    begin
  if( reset='1') then
    cnt <=(others =>'0');
  elsif reset='0' then
    if (clk'event and clk='1') then
   ONES <= (others => '1');
   ZEROS <= (others =>'0');
    temp1 <= to_integer(unsigned(cnt)); 
  
    cnt <=  std_logic_vector(to_unsigned(temp1+1,G_DATA_WIDTH))  when (opcode='01' and cnt/=ONES ),
             ZEROS     when opcode='01' and cnt=ONES , 
            std_logic_vector(to_unsigned(temp1-1,G_DATA_WIDTH))  when opcode='10' and cnt/=ZEROS  ,
            ONES                                         when opcode='10' and cnt=ZEROS  ,
            cnt                                          when opcode='00' ,                                          
            data_in when others ;
  end if;
end if;                                                                                              
end process; 
end arc_counter;

configuration cfg_counter of counter is
  for arc_counter
  end for;
end cfg_counter;

it wrote in the compiler the errors:

Cannot read output "cnt".

Illegal sequential statement.

counter.vhd(34): near ",": expecting ';'




​

 

[joris]

You are not allowed to 'read' the current cnt signal because it is an output signal.
You will have to introduce a help signal for it.

Also, you are not allowed to use this syntax inside a process:

val <=  a  when true,
           b when others;

architecture arc_counter of counter is
  SIGNAL temp1:   integer;
  signal ZEROS:  std_logic_vector(G_DATA_WIDTH-1 downto 0);
  signal ONES:   std_logic_vector(G_DATA_WIDTH-1 downto 0);
  
  cnt_curr : std_logic_vector(G_DATA_WIDTH-1 downto 0));
begin
  process(reset,clk)
    begin
  if( reset='1') then
    cnt_curr <=(others =>'0');
  elsif reset='0' then
    if (clk'event and clk='1') then
   ONES <= (others => '1');
   ZEROS <= (others =>'0');
    temp1 <= to_integer(unsigned(cnt)); 
  
    if (opcode='01' and cnt/=ONES ) then
      cnt_curr <=  std_logic_vector(to_unsigned(temp1+1,G_DATA_WIDTH));
    elsif ( opcode='01' and cnt_curr=ONES) then
       cnt_curr <=  ZEROS;
    elsif ( opcode='10' and cnt_curr/=ZEROS ) then
      cnt_curr <=  std_logic_vector(to_unsigned(temp1-1,G_DATA_WIDTH));
    elsif ( opcode='10' and cnt_curr=ZEROS ) then
      cnt_curr <=  ONES;
    elsif ( opcode='00'  ) then
      cnt_curr <= cnt_curr;
    else
      cnt_curr <= data_in;
    end if;
  end if;
end if;                                                                                              
end process; 

cnt <= cnt_curr;
end arc_counter;

 

[see-me]

thanks very much i solvd the problems

now i am trying to do a test_banch for this counter

library IEEE;
use IEEE.std_logic_1164.all;
use IEEE.std_logic_arith.all;



entity shift_reg is
    PORT ( count : BUFFER bit_vector(8 downto 1));
end;

architecture only of shift_reg is
  
  constant GEN: integer := 8;


component counter 
  generic(G_DATA_WIDTH : integer := 8);
  port(clk,reset, load : in std_logic;
       opcode : in std_logic_vector (1 downto 0);
       data_in : in std_logic_vector(G_DATA_WIDTH-1 downto 0);
       cnt : out std_logic_vector(G_DATA_WIDTH-1 downto 0));
end component;


SIGNAL clk1   : std_logic := '0';
SIGNAL reset1 : std_logic := '0';
SIGNAL load1 : std_logic := '0';
signal opcode1: std_logic_vector (1 downto 0);
signal  DATA1 :  std_logic_vector(GEN-1 downto 0);
signal  cnt1 :  std_logic_vector(GEN-1 downto 0);
begin

dut : counter 
  generic map (G_DATA_WIDTH => GEN);
   PORT MAP (clk => clk1,reset => reset1,load => load1,opcode => opcode1,data_in => DATA1,cnt => cnt1);

clock : PROCESS
   begin
     DATA1=1;
   opcode="01";
   wait for 10 ns; clk  <= not clk;
end PROCESS clock;

stimulus : PROCESS
   begin
   wait for 5 ns; reset  <= '1';
   wait for 4 ns; reset  <= '0';
   wait;
end PROCESS stimulus;


end only;

it wrote alot of errors like:

(vcom-1035) Formal port "clk" has OPEN or no actual associated with it.
(vcom-1035) Formal port "reset" has OPEN or no actual associated with it.
(vcom-1035) Formal port "load" has OPEN or no actual associated with it.
(vcom-1035) Formal port "opcode" has OPEN or no actual associated with it.
: (vcom-1035) Formal port "data_in" has OPEN or no actual associated with it.

near "PORT": syntax error

Illegal target for signal assignment.


i reallydont know where is the problem

i will be glad for help
thnaks in advance:adore:

 

[joris]

These are subtle mistakes...
I have to say the error messages your tool is giving aren't very clear.

GHDL gave these:

shift_reg.vhdl:35:4: unexpected token 'port' in a concurrent statement list
shift_reg.vhdl:39:11: "<=" or ":=" expected instead of =
shift_reg.vhdl:40:10: "<=" or ":=" expected instead of =
/usr/lib/ghdl/bin/ghdl: compilation error

There are two errors:

1. Don't put a semicolon after the generic map:

dut : counter 
  generic map (G_DATA_WIDTH => GEN)
   PORT MAP (clk => clk1,reset => reset1,load => load1,opcode => opcode1,data_in => DATA1,cnt => cnt1);

2. The other error lines should read like

--   DATA1<=1;
     opcode1<="01";

I'm not sure about that first line -- assigning an integer to a std_logic_vector seems strange, but I suppose it's allowed with the (non-standard) std_logic_arith library