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Altera_Forum's avatar
Altera_Forum
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14 years ago

Down Counting State Machine problem

Greetings

I have a state machine that needs to count down from a given number (0-9) while at the same time toggling back and fourth to another state machine.

So if I have the number three come in. I need it to go into state 1 count down (1 second), subtract one, go into state 2 where it is delayed one second, return to state 1 where it will delay 1 second, subtract one (It would be 1 now) and return once again to state 2, where it would delay and finally return to state 2 where the last one will be subratected, it will have a final 1 second delay and exit to the next state after hitting zero.

Here is my code. apparently if I load three into it. It will delay the one second for the first number but the 2 and the 1 only have one clock pulse before going to zero and exiting. 

when HighError2 =>
          
     if (shortwait = 0 and HighBits = "0000" ) then 
     state <= waitone;
     longwait <= twosecdelay;
     shortwait <= halfsecdelay;
     elsif (HighBits > "0000") then
      if(shortwait = 0) then
      HighBits <= (HighBits - "0001");
      else
      shortwait <= (shortwait - 1);
      ErrorLED <= '1';
      FLTline  <= '1';
      end if;
     else state <= HighError2;
     end if;

does anyone see any blatent errors?

Thanks

3 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    I dont really understand what you are trying to do.

    Where is the input?

    what are you trying to wait on? is it just mean to wait for N seconds where N is the input (that I dont quite understand from your code).
  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    14 years ago

    Yes, I am counting down from (400) for simulation purposes

    Here is my latest... Still having problems with signal tap 

    when HighError1 =>
     
     ErrorLED <= '0';
     FLTline  <= '1';
     shortwait <= shortwait - 1;
      if (shortwait = 0) then 
      state <= HighError2;
      shortwait <= halfsecdelay;
      else state <= HighError1;
      end if;
     
    when HighError2 =>
          
     if(HighBits = "0000")then
      state <= waitone;
      longwait <= twosecdelay;
      shortwait <= halfsecdelay;
     elsif(HighBits > "0000")then
      shortwait <= (shortwait - 1);
      ErrorLED <= '1';
      FLTline  <= '1';
      if(shortwait = 0)then
       HighBits <= (HighBits - "0001");
       longwait <= twosecdelay;
       shortwait <= halfsecdelay;
       state <= HighError1;
      else state <= HighError2;
      end if;
     else state <= HighError2;
     end if;