Dual Modulus Divider

Altera_Forum · ‎06-22-2010

Hola All,

this is my first attempt at a dual modulus divider. Eventually I want to use it in a Fractional_N PLL, but one step at a time. I still have to see how it holds up in a gate-level simulation. You can see part of the functional simulation below. the output follows the input when the division is set to 1 or 0. Around the 480 mark you see the pulses on Y being half that of clk, which makes sense because the division is 2 ( Num + 1), because Np1 is high.

Anyway, I'm still quite the newb so if you have any suggestions let me know.

http://sphotos.ak.fbcdn.net/hphotos-ak-ash2/hs014.ash2/34080_10150216062425055_754135054_13088368_6268216_n.jpg


Library ieee;
Use ieee.std_logic_1164.all;
Use ieee.numeric_std.all;
--------------------------------------->
Entity Mod_Div_1 is
  Generic(k : integer :=3);
  Port(
        clk : in std_logic;
        Num : in Unsigned (k downto 0);
        Np1 : in std_logic;
        Y   : out std_logic
      );
End Mod_Div_1;
----------------------------------------->
Architecture Int_N of Mod_Div_1 is
  Signal Count :integer Range 0 to ((2**(k+1))-1);
  Signal Y_int2 : std_logic :='0';
Begin
  
  Y <= clk when (((Num = "00" or Num = "01") and Np1 = '0') or (Num = "00" and Np1 ='1')) else
       Y_int2;
  ---------------- Divider code -------------------------------------
  
  N_Divide : Process(clk)
    Variable count_int : integer range 0 to ((2**(k+1))-1) :=0; 
    Variable Num_Val : Integer range 0 to ((2**(k+1))-1);
    Variable Y_int : std_logic :='0';
    
  Begin
      Num_Val := TO_INTEGER(Num);
      
      if (Np1 = '1') then
        Num_Val := Num_Val + 1;
      End if;
      
      if(clk'EVENT and clk ='1' and (Num_Val /= 0 or Num_Val /= 1)) then
        count_int := count_int + 1;
        if(count_int = Num_Val) then
          Y_int := '1';
          count_int :=0;
        Else
          Y_int := '0';
        End if;
        if(count_int > Num) then
          count_int := 0;
        end if;
        Y_int2 <= Y_int;
        
       End if;
       Count <= count_int;
   End Process N_Divide;
   
   --------------------------------------------------------------------
End Int_N;