用VHDL编数字时钟
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LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
USE IEEE.STD_LOGIC_UNSIGNED.ALL;
USE IEEE.STD_LOGIC_SIGNED.ALL;
USE IEEE.STD_LOGIC_ARITH.ALL;
ENTITY Clock IS
PORT( CLK5:IN STD_LOGIC;
CLK3:IN STD_LOGIC; --时钟控制
SET1:IN STD_LOGIC;
SET2:IN STD_LOGIC; --模式控制
SEG_SEL:OUT STD_LOGIC_VECTOR(2 DOWNTO 0);
SEG_DA :OUT STD_LOGIC_VECTOR(7 DOWNTO 0)
);
END Clock;
ARCHITECTURE ADO OF Clock IS
SIGNAL SEG_BUF1,SEG_BUF2,SEG_BUF3,SEG_BUF4:STD_LOGIC_VECTOR(3 DOWNTO 0); SIGNAL SEG_BUF5,SEG_BUF6,SEG_BUF7,SEG_BUF8:STD_LOGIC_VECTOR(3 DOWNTO 0); SIGNAL SEG_CNT :STD_LOGIC_VECTOR(2 DOWNTO 0);
SIGNAL SEG_TEMP:STD_LOGIC_VECTOR(3 DOWNTO 0);
BEGIN
PROCESS (CLK3) --扫描累加
BEGIN
IF CLK3'EVENT AND CLK3='1' THEN
SEG_CNT<=SEG_CNT+1;
END IF;
END PROCESS;
SEG_SEL<=SEG_CNT;
SEG_BUF3<="1111";
SEG_BUF6<="1111";
PROCESS(SEG_CNT,SEG_BUF1,SEG_BUF2,SEG_BUF3,SEG_BUF4,SEG_BUF5,SEG_BUF6,SEG_BUF7 ,SEG_BUF8)
BEGIN
CASE SEG_CNT IS
WHEN "000" => SEG_TEMP<=SEG_BUF1;
WHEN "001" => SEG_TEMP<=SEG_BUF2;
WHEN "010" => SEG_TEMP<=SEG_BUF3;
WHEN "011" => SEG_TEMP<=SEG_BUF4;
WHEN "100" => SEG_TEMP<=SEG_BUF5;
WHEN "101" => SEG_TEMP<=SEG_BUF6;
WHEN "110" => SEG_TEMP<=SEG_BUF7;
WHEN "111" => SEG_TEMP<=SEG_BUF8;
WHEN OTHERS => NULL;
END CASE;
END PROCESS;
PROCESS (SEG_TEMP) --显示转换
BEGIN
CASE SEG_TEMP IS
WHEN "0000" => SEG_DA<=x"3F";
WHEN "0001" => SEG_DA<=x"06";
WHEN "0010" => SEG_DA<=x"5B";
WHEN "0011" => SEG_DA<=x"4F";
WHEN "0100" => SEG_DA<=x"66";
WHEN "0101" => SEG_DA<=x"6D";
WHEN "0110" => SEG_DA<=x"7D";
WHEN "0111" => SEG_DA<=x"07";
WHEN "1000" => SEG_DA<=x"7F";
WHEN "1001" => SEG_DA<=x"6F";
WHEN "1010" => SEG_DA<=x"77";
WHEN "1011" => SEG_DA<=x"7B";
WHEN "1100" => SEG_DA<=x"39";
WHEN "1101" => SEG_DA<=x"3E";
WHEN "1110" => SEG_DA<=x"79";
WHEN "1111" => SEG_DA<=x"00";
END CASE;
END PROCESS;
PROCESS(Clk5,SET1,SET2)
BEGIN
if(SET1='1' AND SET2='1') then --系统复位
SEG_BUF1<="0000";
SEG_BUF2<="0000";
SEG_BUF4<="0000";
SEG_BUF5<="0000";
SEG_BUF7<="0000";
SEG_BUF8<="0000";
elsif(Clk5'event and Clk5='1') then
if(SET1='1' and SET2='0') then --调节小时
if(SEG_BUF7=9) then
SEG_BUF7<="0000";
SEG_BUF8<=SEG_BUF8+1;
elsif(SEG_BUF8>=2 and SEG_BUF7>=3) then
SEG_BUF7<="0000";
SEG_BUF8<="0000";
else
SEG_BUF7<=SEG_BUF7+1;
end if;
elsif(SET1='0' and SET2='1') then --调节分钟
if(SEG_BUF4=9) then
SEG_BUF4<="0000";
if(SEG_BUF5=5) then
SEG_BUF5<="0000";
else
SEG_BUF5<=SEG_BUF5+1;
end if;
else
SEG_BUF4<=SEG_BUF4+1;
end if;
elsif(SET1='0' and SET2='0') then --正常计数
SEG_BUF1<=SEG_BUF1;
SEG_BUF2<=SEG_BUF2;
SEG_BUF4<=SEG_BUF4;
SEG_BUF5<=SEG_BUF5;
SEG_BUF7<=SEG_BUF7;
SEG_BUF8<=SEG_BUF8;
if(SEG_BUF1=9) then
SEG_BUF1<="0000";
if(SEG_BUF2=5) then
SEG_BUF2<="0000";
if(SEG_BUF4=9) then
SEG_BUF4<="0000";
if(SEG_BUF5=5) then
SEG_BUF5<="0000";
if(SEG_BUF7=9) then
SEG_BUF7<="0000";
SEG_BUF8<=SEG_BUF8+1;
elsif(SEG_BUF8>=2 and SEG_BUF7>=3) then
SEG_BUF7<="0000";
SEG_BUF8<="0000";
else
SEG_BUF7<=SEG_BUF7+1;
end if;
else
SEG_BUF5<=SEG_BUF5+1;
end if;
else