8.20 电子时钟 VHDL 程序与仿真
1.
10 进制计数器设计与仿真
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1)10 进制计数器 VHDL 程序
--文件名:counter10.vhd。
--功能:10 进制计数器,有进位 C
--最后修改日期:2004.3.20
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_ARITH.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
entity counter10 is
Port ( clk : in std_logic;
reset : in std_logic;
din : in std_logic_vector(3 downto 0);
dout : out std_logic_vector(3 downto 0);
c:out std_logic);
end counter10;
architecture Behavioral of counter10 is
signal count : std_logic_vector(3 downto 0);
begin
dout <= count;
process(clk,reset,din)
begin
if reset='0'then
count <= din ;
c<='0';
elsif rising_edge(clk) then
if count = "1001" then
count <= "0000";
c<='1';
else
count <= count+1;
c<='0';
end if;
end if;
end process;
end Behavioral;
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2) 10 进制计数器仿真
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