loading
When\When\When others=>h0<=\
End case; When \
Case lie is --“田”字设计
When\When\When\When\When\When\When\When\When\When others=>h0<=\
End case;
When \
Case lie is --“口”字设计
When\When\When\When\When\When\When\When others=>h0<=\ End case;
When others=>h0<=\
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End case; End if; End if; End process;
2.4.3字母循环扫描及期间的延时环节
为使字母不断地循环显示，并且使每个字母之间有停顿，就需要在中间加一定的延时和循环环节。在这一环节中，可以通过修改其数值来控制每个字母的显示时间。
其程序如下： process(clk)
variable int: integer range 0 to 10000; begin
if clk’event and clk=’1’then if int<10000 then int:=int+1; else
int:=0;
if next1=”11”then
next1<=”00”;
else
next1<= next1+’1’;
end if;
end if;
end if;
end process;
2.5 整个完整的程序
library ieee;
use ieee.std_logic_1164.all; use ieee.std_logic_unsigned.all; entity yz_ok is
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port(enable,clk:in std_logic;
sel:out std_logic_vector(3 downto 0);
h0,h8:out std_logic_vector(7 downto 0));
end yz_ok;
architecture count of yz_ok is
signal lie:std_logic_vector(3 downto 0); signal next1: std_logic_vector(1 downto 0);
begin
a1:process(clk,enable)
begin
If clk'event and clk='1'then
If enable='1' then
If lie>\ Lie<=lie-\Else
Lie<=\End if;
End if;
End if; Sel<=lie;
End process;
a2:process(enable,clk) begin
If clk'event and clk='1'then
If enable='1' then
Case next1 is
When \
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Case lie is
When \When \When \When \When \When \When \When \When \When \When \When others=>h0<=\
End case; When \Case lie is
When\When\When\When\When\When\When\When others=>h0<=\
End case; When \
Case lie is
When\When\
11