FPGA的一个VHDL实现1秒LED闪烁一次的程序

talentyxc

程序思路很简单，就是利用50MHz的外部时钟输入，经过2次分频得到1秒的精确定时，给LED取反。


LIBRARY IEEE;
USE IEEE.STD_LOGIC_1164.ALL;
--USE IEEE.STD_LOGIC_ARITH.ALL;
--USE IEEE.STD_LOGIC_UNSIGNED.ALL;

entity led is
?? ?port(led1,led2,led3,led4ut bit;clk:in bit);
end led;

architecture led_blink of led is

begin
?? ?process(clk)
?? ?variable s1:integer:=0;
?? ?variable s2:integer:=0;
?? ?begin
?? ??? ?i1:if (clk'event and clk='1') then
?? ??? ??? ?s1:=s1+1;
?? ??? ??? ?
??? ??? ??? if(s1>20000) then
??? ??? ??? ??? s2:=s2+1;
??? ??? ??? ???
??? ??? ??? ??? if(s2>2500 and s2