Mod_N Counter-數位邏輯技術

Introduction to Counter

Main Idea of the Implementation of Mod_N Counter

Main Idea of the Implementation

• A Mod-N counter is triggered by a clock. After declaring a variable (countr) to store counting information, when rising edge of a clock is detected, . When , clear countr to zero.

• In order to observe the changing of numbers, the code below uses a frequency divider.(1hz)

library ieee;
use ieee.std_logic_1164.all;
use ieee.std_logic_unsigned.all;
use ieee.numeric_std.all;

entity counter is
port (
    CLK : in std_logic;
    COUNT : out std_logic_vector(3 downto 0)
);
end entity counter;

architecture behavioral of counter is

component to_1hz_divider is
	port(
		
		CLK_IN: in std_logic;
		CLK_OUT: out std_logic
	
	);
end component;

signal CLK_COUNTR: std_logic;
signal countr: std_logic_vector(4 downto 0);

begin
	
	divider: to_1hz_divider
		port map(
			
			CLK_IN => CLK,
			
			CLK_OUT => CLK_COUNTR
		
		);
	
	process(CLK_COUNTR)
	begin
	
		if rising_edge(CLK_COUNTR) then
			
			countr <= countr + 1;
			
		end if;
		
			if countr(4) = '1' then
				
				countr <= (others => '0');
			
			end if;
	
	end process;
	
	COUNT <= countr(3 downto 0);
	 
end architecture behavioral;

• With 7-seg display

  library ieee;
  use ieee.std_logic_1164.all;
  
  entity counter_with7seg is
  	port(
  		
  		CLK_50mhz: in std_logic;
  		
  		display: out std_logic_vector(6 downto 0)
  	
  	);
  end entity;
  
  architecture behavioral of counter_with7seg is
  
  signal data_temp: std_logic_vector(3 downto 0);
  
  component counter is
  port (
  	CLK : in std_logic;
     COUNT : out std_logic_vector(3 downto 0)
  );
  end component;
  
  component seven_segement_decoder is
  port (
  	data: in std_logic_vector(3 downto 0);
  	display: out std_logic_vector(6 downto 0)
  );
  end component;
  
  begin
  
  	countr: counter
  		port map(
  			
  			CLK => CLK_50mhz,
  			
  			count => data_temp
  		);
  		
  	display0: seven_segement_decoder 
  		port map(
  			
  			data => data_temp,
  			
  			display => display
  		);
  
  end behavioral;