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Forum: FPGA, VHDL & Verilog help error 10822 vhdl


von daniel (Guest)


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i will be thankful if somebody will can help me..
my aim is to make a block that get 3 inputs:
a clc that change every 0.1 sec
a input that get '1' every time i press key0
and reset button that reset my count

the aim is to count the number of time i press and when there is 3 secs 
that i dont press i get the count of the time i pressed
i tried to it with this code"
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library ieee;
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use ieee.std_logic_1164.all;
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use ieee.std_logic_unsigned.all;
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use ieee.std_logic_arith.all;
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entity CLAPNUM is 
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   port( 
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    resetN, clk : in std_logic;
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    key0         : in std_logic   ;
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    sinus      : out  std_logic_vector(4 downto 0));
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end CLAPNUM ; 
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architecture arc_CLAPNUM of CLAPNUM is 
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signal countera : std_logic_vector(4 downto 0) :="00000"  ;
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signal counterb : std_logic_vector(4 downto 0) :="00000" ;
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signal cinout   : std_logic := '0' ;
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signal moda   : std_logic := '0' ;
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begin 
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process ( resetN key0, clk)
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  begin
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    if resetN = '0' then
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    countera<="00000" ;
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    counterb<="11110";
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  elsif (key0 ='1') and moda='0' then
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    countera<= countera+"00001" ;
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    counterb<="11110";
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  elsif (rising_edge(clk))  then
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    if counterb/="00000" and (key0 ='0') then
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      counterb <= counterb-"00001";
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    else      
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      moda <= '1';
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    end if;
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  elsif moda='1' then
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  sinus<= countera;
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  end if;
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   end process;
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end arc_CLAPNUM;

but clearly it dosent work...
can someone help me plz?

: Edited by Moderator
von Lothar M. (lkmiller) (Moderator)


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First have a look at the attached sreenshot...

> but clearly it dosent work...
And HOW did you see that?
Did you do a SIMULATION?
What ERROR messages or WARNINGS did you get?
And why do you ignore them all?

In fact the problem here is the well known and famous "combinatorial 
loop":
as long as key0 is 1 and moda is 0 the countera is counting upwards 
without any clock at maximum and random speed:
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  elsif (key0 ='1') and moda='0' then
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    countera<= countera+"00001" ;
Try Google translator on that:
http://www.lothar-miller.de/s9y/archives/42-Kombinatorische-Schleifen.html

Let me ask you: where did you see this structure in literature?
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begin process ( resetN key0, clk)
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begin
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if resetN = '0' then
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  ...
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elsif (key0 ='1') and moda='0' then
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  ...
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elsif (rising_edge(clk)) then
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  ...
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end if;
There's only one way to desrcibe a synchronous process:
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begin process ( resetN, clk)
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begin
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if resetN = '0' then
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  ...
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elsif (rising_edge(clk)) then
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  ...
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end if;

Beside the whole things above: the sensitivity list is incomplete, moda 
ist missing. Therefore a simulation will show wrong results...

BTW: congratulations to use the 1-process-FSM. You are a big step 
further than in the thread https://embdev.net/topic/386779

: Edited by Moderator

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