I know this question has been answered some times already, but all those answers are specific to the according code.
That's why I am asking it again. Why do I get this error and how do I fix it.
I am trying to make a 8-bit up/down counter.
The error:
Error (10500): VHDL syntax error at UpDownCounter.vhd(30) near text
"PROCESS"; expecting "if"
LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.all;
USE IEEE.STD_LOGIC_ARITH.all; -- needed for arithmetic increment
USE IEEE.STD_LOGIC_UNSIGNED.all;
ENTITY UpDownCounter IS
port( inA, inB : IN STD_LOGIC ;
Max_count: IN std_logic_vector(7 DOWNTO 0);
result : OUT STD_LOGIC_VECTOR(7 DOWNTO 0)
);
END UpDownCounter;
Architecture behavior of UpDownCounter is
signal internal_result : STD_LOGIC_VECTOR(7 DOWNTO 0);
BEGIN
result <= internal_result;
PROCESS(inA, inB)
BEGIN
IF (inA'EVENT and inA = '1') THEN
IF internal_count < Max_count THEN
internal_result <= internal_result + 1;
END IF;
ELSIF (inB'EVENT and inB = '1') THEN
-- Check for maximum count
IF internal_count > Max_count THEN
internal_result <= internal_result - 1;
END IF;
ELSE
internal_result <= "00000000";
END PROCESS;
END behavior;
The help is appreciated!
In your code, the final ELSE is missing the terminating END IF.
This is for the previous ELSE IF and it's corresponding IF which must have an END IF; statement.
Related
I am getting this error in my VHDL code :
found '0' definitions of operator "=", cannot determine exact
overloaded matching definition for "="
Here is my code:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use ieee.std_logic_unsigned.all;
entity test2 is
Port (clk : in std_logic ;
sclk : out std_logic);
end test2;
architecture Behavioral of test2 is
signal cnt : std_logic_vector(2 downto 0):=(others=>'0');
begin
process(clk)
begin
if rising_edge(clk) then
if cnt(2) = "111" then
sclk <= clk ;
else
cnt <= cnt+1;
end if;
end if;
end process;
end Behavioral;
Where exactly is the problem?
the "cnt" is 3bit signal like (bit2,bi1,bit0). When you write cnt(2) it will mean cnt(bit2), however you compared it with "111".
In my VHDL code I have an error in sig_out_real <= X"00" & sig_in when sig_in(7)='0' else X"ff" & sig_in;.
I don't think it is a syntax error. But Quartus shows an error at that point.
I don`t understand why it's an error.
Can anyone provide information:
-- Error--
Error (10500): VHDL syntax error at S8BT16B.vhd(35) near text "when"; expecting ";"
library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_signed.all;
use ieee.std_logic_arith.all;
use work.fft_package.all;
entity S8BT16B is
port(
clk_50 : in std_logic;
clk_baud : in std_logic;
main_reset : in std_logic;
enable : in std_logic;
sig_in : in signed (7 downto 0);
sig_out : out complex;
valid_output : out std_logic
);
end S8BT16B;
architecture Behavioral of S8BT16B is
type state is (idle,start);
signal state_reg, next_state_reg : state;
signal sig_out_real : signed(15 downto 0);
begin
state_change : process(clk_50, main_reset)
begin
if (main_reset = '1' or enable = '0') then
state_reg <= idle;
elsif (main_reset ='0' and enable = '1') then
state_reg <= next_state_reg;
end if;
end process;
S8BT16B_active : process(clk_baud, state_reg)
begin
if (state_reg = idle) then
sig_out_real <="0000000000000000";
sig_out <=(sig_out_real,"0000000000000000");
next_state_reg <= start;
valid_output <= '0';
elsif (state_reg = start and enable = '1') then
sig_out_real <= X"00" & sig_in when sig_in(7)='0' else X"ff" & sig_in;
sig_out <= (signed_converted_input, "0000000000000000");
next_state_reg <= idle;
valid_output <= '1';
end if;
end process;
end Behavioral;
You code does not present a Minimal, Complete, and Verifiable example.
The package fft_package presumably containing the type declaration for complex is not present.
The declaration for signed_converted_input is also not present.
A sequential conditional signal assignment statement is only available in VHDL-2008.
There's a good argument to be made that the Synopsys packages std_logic_arith and std_logic_signed are not compatible with IEEE Std 1076-2008's defined package std_logic_1164. It's possible they've been re-written to accomidate the new definitions of std_logic_vector and std_ulogic vector, although not if they work without -2008 compatibility, without some serious automagic on the part of ALDEC.
If passing a -2008 compatibility flag doesn't fix things for you the simplest thing you can do is replace the sequential conditional signal assignment statement with two simple signal assignment statements inside an if statement:
library ieee;
use ieee.std_logic_1164.all;
-- use ieee.numeric_std.all;
use ieee.std_logic_arith.all;
package fft_package is
type complex is record
sig_real: signed (15 downto 0);
sig_imaginary: signed (15 downto 0);
end record;
constant signed_converted_input: signed (15 downto 0) := (others => '0');
end package;
library ieee;
use ieee.std_logic_1164.all;
-- use ieee.numeric_std.all;
use ieee.std_logic_arith.all;
use work.fft_package.all;
entity S8BT16B is
port(
clk_50: in std_logic;
clk_baud: in std_logic;
main_reset: in std_logic;
enable: in std_logic;
sig_in: in signed (7 downto 0);
sig_out: out complex;
valid_output: out std_logic
);
end S8BT16B;
architecture Behavioral of S8BT16B is
type state is (idle,start);
signal state_reg, next_state_reg: state;
signal sig_out_real: signed(15 downto 0);
begin
state_change:
process(clk_50, main_reset)
begin
if (main_reset = '1' or enable = '0') then
state_reg <= idle;
elsif (main_reset ='0' and enable = '1') then
state_reg <= next_state_reg;
end if;
end process;
S8BT16B_active:
process(clk_baud, state_reg)
begin
if state_reg = idle then
sig_out_real <= "0000000000000000";
sig_out <=(sig_out_real,"0000000000000000");
next_state_reg <= start;
valid_output <= '0';
elsif state_reg = start and enable = '1' then
-- sig_out_real <= X"00" & sig_in when sig_in(7)='0' else
-- X"ff" & sig_in;
if sig_in(7) = '0' then
sig_out_real <= X"00" & sig_in;
else
sig_out_real <= X"ff" & sig_in;
end if;
sig_out <= (signed_converted_input, "0000000000000000");
next_state_reg <= idle;
valid_output <= '1';
end if;
end process;
end Behavioral;
This code analyzes, elaborates and simulates (to show there are no length mismatches without regards to sig_in(7) = '0') while any claim to it's functionality is not made. The length looks right in the assignments to sig_out_real.
And of course without seeing the actual contents of your package fft_package claims to syntax and semantic validity can't be absolutely made (the faux package and your modified code are consistent with each other).
guys im trying to code a simple counter in VHDL but i always get this error:
Error: C:/Users/usrname/dir1/dir2/dir3/counter.vhd(22): near "rising_edge": (vcom-1576) expecting == or '+' or '-' or '&'.
Here is my Code:
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity counter is
port (
EXT_RST : in std_logic;
EXT_CLK : in std_logic;
EXT_LED : out std_logic_vector(7 downto 0)
);
end counter;
architecture fast of counter is
signal count : std_logic_vector(7 downto 0);
begin
process(EXT_CLK, count)
begin
if (EXT_RST = '1') then
count <= "00000000";
elseif rising_edge(EXT_CLK) then
count <= count + '1';
end if;
end process;
EXT_LED <= count;
end fast;
Has anyone an idea why im getting this error?
Besides the elsif Lars Asplund suggested using in his comment use type conversions for `count:
count <= std_logic_vector(unsigned(count) + 1);
or use package numeric_std_unsigned (VHDL -2008 only) instead of numeric_std.
Notice the 1 instead of '1' and type conversions. Those aren't needed with numeric_std_unsigned which has a "+" adding operator function with this signature:
[STD_ULOGIC_VECTOR,STD_ULOGIC return STD_ULOGIC_VECTOR]
Using package numeric_std you can also make count an unsigned instead of std_logic_vector and convert for the LED assignment -
EXT_LED <= std_logic_vector(count);
Also, count doesn't need to be in the process sensitivity list:
process(EXT_CLK)
There are no assignments in the process where the value of count is used except on the clock edge.
Modifying your code with the first suggestion and indenting (which helps show the sensitivity list doesn't need count:
library ieee;
use ieee.std_logic_1164.all;
use ieee.numeric_std.all;
entity counter is
port (
EXT_RST : in std_logic;
EXT_CLK : in std_logic;
EXT_LED : out std_logic_vector(7 downto 0)
);
end counter;
architecture fast of counter is
signal count : std_logic_vector(7 downto 0);
begin
process(EXT_CLK)
begin
if (EXT_RST = '1') then
count <= "00000000";
elsif rising_edge(EXT_CLK) then
count <= std_logic_vector(unsigned(count) + 1);
end if;
end process;
EXT_LED <= count;
end fast;
This analyzes, elaborates and will simulate.
This prompts the question of how EXT_RST and EXT_CLK are derived should you actually synthesize your design. If they are from buttons (particularly the clock), debounce could be necessary even with membrane switches which can age and later bounce.
I'm new to the world of VHDL and I'm getting this error saying Syntax error near process. I checked for the solutions and found that there may be a missing end if statement but in my code I'm not having that problem.
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use ieee.std_logic_unsigned.ALL;
USE ieee.std_logic_arith.ALL;
use STD.textio.all;
entity Main_Architecture is
port(
SEN: out std_logic;
reset: in std_logic;
clk: in std_logic
);
end Main_Architecture;
architecture Behavioral of Main_Architecture is
signal main_counter : std_logic_vector(7 downto 0) := "00000000";
signal mux: std_logic_vector(1 downto 0) := "00";
signal output : std_logic_vector(7 downto 0);
signal main_counter_int : integer range 0 to 127:=0;
signal main_generator : std_logic_vector(7 downto 0);
begin
process(main_counter,reset,clk)
variable x: std_logic;
variable y: std_logic;
variable z: integer;
begin
if(reset = '1') then
main_counter <= (others => '0');
end if;
if(clk'event and clk='1') then
if(mux="00") then --load main counter
y:= main_counter(0);
x:= (main_counter(0)XOR main_counter(6) XOR main_counter(7));
main_counter(7 downto 1) <= main_counter(6 downto 0);
main_counter(0)<=x;
main_counter <= main_counter+'1';
output(0)<=y;
output(1)<=main_counter(0);
output(2)<=main_counter(1);
output(3)<=main_counter(2);
output(4)<=main_counter(3);
output(5)<=main_counter(4);
output(6)<=main_counter(5);
main_counter_int<=conv_integer(output);
if(main_counter >= "11111111") then
mux <= "01";
end if;
end if;
if(mux="01") then
if(main_counter_int < 2) then
z:=1;
else if(main_counter_int < 4) then
z:=2;
else if(main_counter_int < 8) then
z:=3;
else if(main_counter_int < 16) then
z:=4;
else if(main_counter_int < 32) then
z:=5;
else if(main_counter_int < 64) then
z:=6;
else if(main_counter_int < 128) then
z:=7;
end if;
end if;
end if;
end process; -------- LINE 104 -------
end Behavioral;
Also I want to create a std_logic_vector which has a size from value z to 0. i.e. A vector of size z+1. How can i make it?
Question part 1
Without looking into any other issues in your code, I think the problem is this section, which I have re-formatted to show how many 'end if' statements you are missing:
if(mux="01") then
if(main_counter_int < 2) then
z:=1;
else
if(main_counter_int < 4) then
z:=2;
else
if(main_counter_int < 8) then
z:=3;
else
if(main_counter_int < 16) then
z:=4;
else
if(main_counter_int < 32) then
z:=5;
else
if(main_counter_int < 64) then
z:=6;
else
if(main_counter_int < 128) then
z:=7;
end if;
end if;
I think you probably wanted to use elsif instead of else if.
Question part 2
For the second part of your question, assuming you want to produce code that can be realised in hardware, there is no such thing as a run-time sized std_logic_vector. The best you can do is to make your vector have the maximum size that it could need, then only assign or use parts of it, based on the value of 'z'.
A couple of other points:
USE ieee.std_logic_arith.ALL;
This is not a 'true' standard library, and there are many other answers where people recommend against using this library. If you need to perform math functions (e.g. +), USE ieee.numeric_std.all;, then create signals of type signed or unsigned. In your example, main_counter would be declared signal main_counter : unsigned(7 downto 0) := "00000000";. Operations like + can then be performed on this signal, with no ambiguity as to whether it is supposed to be signed or not.
Lastly, the section:
output(0)<=y;
output(1)<=main_counter(0);
output(2)<=main_counter(1);
output(3)<=main_counter(2);
output(4)<=main_counter(3);
output(5)<=main_counter(4);
output(6)<=main_counter(5);
could more compactly be written using the concatenation operator & as
output(6 downto 0) <= main_counter(5 downto 0) & y;
Side note: output(7) doesn't seem to ever be assigned.
I am doing something like this:
x : in STD_LOGIC_VECTOR(15 downto 0);
signal x_d: std_logic_vector(15 downto 0);
type inp_concat_array is array (0 to 15) of std_logic_vector(1 downto 0);
signal inp_concat : inp_concat_array;
process (clk, reset)
begin
if (rising_edge(clk)) then
if (reset = '1') then
for i in 0 to 15 loop
x_d(i) <= '0';
end loop;
else
for i in 0 to 15 loop
x_d(i) <= x(i);
end loop;
end if;
end if;
end process;
for j in 0 to 15 loop
inp_concat(j) <= x(j) & x_d(j);
end loop;
Xilinx ISE 14.2 gives following errors
Syntax error near "for"
Syntax error near "loop"
Can i use asynchronous assignments in FOR loop?
The concurrent for loop must be made with a generate statement like:
inp_concat_loop : for j in 0 to 15 generate
inp_concat(j) <= x(j) & x_d(j);
end generate;
or in a process as described in David Koontzs answer.
Without seeing an entire design description answering your question could be a bit risky. You present us with a code fragment and no line numbers for the syntax error. The code fragment contains three for loops.
Now if this fragment represents a continuous segment extracted from a design unit (an architecture) it would appear that you are trying to use a loop statement (the for loop, a sequential statement appropriate for a process or subprogram) in a place appropriate for a concurrent statement (the architecture body).
Providing missing bits for something that might analyze:
library ieee;
use ieee.std_logic_1164.all;
entity asyn is
port (
x : in STD_LOGIC_VECTOR(15 downto 0);
clk: in std_logic;
reset: in std_logic
);
end entity;
architecture foo of asyn is
signal x_d: std_logic_vector(15 downto 0);
type inp_concat_array is array (0 to 15) of std_logic_vector(1 downto 0);
signal inp_concat : inp_concat_array;
begin
process (clk, reset)
begin
if (rising_edge(clk)) then
if (reset = '1') then
for i in 0 to 15 loop
x_d(i) <= '0';
end loop;
else
for i in 0 to 15 loop
x_d(i) <= x(i);
end loop;
end if;
end if;
end process;
for j in 0 to 15 loop
inp_concat(j) <= x(j) & x_d(j);
end loop;
end architecture;
And using a different tool yields:
ghdl -a async.vhdl
async.vhdl:32:5: a generate statement must have a label
async.vhdl:32:22: 'generate' is expected instead of 'loop'
In a place appropriate for a concurrent statement in an architecture body the only statement that can have a for keyword is a generate statement, which requires a label.
There is no requirement in VHDL to look ahead to disambiguate syntax errors (which is why you have a vague error message).
A different tool provides a bit better illustration:
nvc -a async.vhdl
** Error: syntax error, unexpected for, expecting process
File async.vhdl, Line 32
for j in 0 to 15 loop
^^^
So if you put the for loop in a process instead it just might analyze:
NEW_PROCESS:
process (x,x_d)
begin
for j in 0 to 15 loop
inp_concat(j) <= x(j) & x_d(j);
end loop;
end process;
Below is a suggestion for a simpler, neater solution. Simulation results follow.
-----------------------------------------------
library ieee;
use ieee.std_logic_1164.all;
-----------------------------------------------
entity test is
port (
clk, reset: in std_logic;
x: in std_logic_vector(15 downto 0);
--test signals:
test: out std_logic_vector(1 downto 0);
test_index: in natural range 0 to 15);
end entity;
-----------------------------------------------
architecture test of test is
signal x_d: std_logic_vector(15 downto 0);
type inp_concat_array is array (0 to 15) of
std_logic_vector(1 downto 0);
signal inp_concat: inp_concat_array;
begin
process (clk, reset)
begin
if rising_edge(clk) then
if reset = '1' then
x_d <= (others => '0');
else
x_d <= x;
end if;
end if;
end process;
gen: for i in 0 to 15 generate
inp_concat(i) <= x(i) & x_d(i);
end generate;
test <= inp_concat(test_index);
end architecture;
-----------------------------------------------
The problem is that your asynchronous for loop is not inside a process, and needs to be: This should do it
process(x,x_d)
begin
for j in 0 to 15 loop
inp_process(j) <= x(j) & x_d(j);
end loop;
end process;