upcnt5.vhd

Serial ADC Interface write in VHDL based on xilinx cpld

-- ************************************************************************
--
-- Owner:		Xilinx Inc.
-- File:  		upcnt5.vhd
--
-- Purpose: 		Up 5-bit counter
--	
--		
-- **************************************************************************


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


entity upcnt5 is
	port(
	      
	     data         : in STD_LOGIC_VECTOR (4 downto 0);    -- Parallel data in
	     cnt_en       : in STD_LOGIC;                        -- Count enable
	     load         : in STD_LOGIC;                        -- Load line enable
 	     clr          : in STD_LOGIC;                        -- Active low clear
	     clk          : in STD_LOGIC;                        -- Clock
	     qout         : inout STD_LOGIC_VECTOR (4 downto 0)
		
	     );
		
end upcnt5;



architecture DEFINITION of upcnt5 is

constant RESET_ACTIVE : std_logic := '0';

signal q_int : UNSIGNED (4 downto 0);

begin

     process(clk, clr)
     begin
          
          -- Clear output register
          if (clr = RESET_ACTIVE) then
	       q_int <= (others => '0');
	       
	  -- On falling edge of clock count
	  elsif (clk'event) and clk = '0' then

	       -- Load in start value
	       if (load = '1') then
		    q_int <= UNSIGNED(data);
	       -- If count enable is high
	       elsif cnt_en = '1' then
		    q_int <= q_int + 1;
	       end if;
	  end if;

     end process;

     qout <= STD_LOGIC_VECTOR(q_int);

end DEFINITION;