Question

怎么使用例化语句将10进制计数器和6进制计数器组成一个60进制减法计数器

Answer 1

六进制计数器源程序cnt6.vhd：

LIBRARY IEEE;

USE IEEE.STD_LOGIC_1164.ALL;

USE IEEE.STD_LOGIC_UNSIGNED.ALL;

ENTITY CNT6 IS

PORT (CLK,CLRN,ENA,LDN:IN STD_LOGIC;

D:IN STD_LOGIC_VECTOR(3 DOWNTO 0);

Q:OUT STD_LOGIC_VECTOR(3 DOWNTO 0);

COUT:OUT STD_LOGIC);

END CNT6;

ARCHITECTURE ONE OF CNT6 IS

SIGNAL CI:STD_LOGIC_VECTOR(3 DOWNTO 0):="0000";

BEGIN

PROCESS(CLK,CLRN,ENA,LDN)

BEGIN

IF CLRN='0' THEN CI