该模块是一个基于verilog的脉冲触发高低电平保持的模块，同时包含了消抖的功能。

主要是针对现今许多开发板上开关是弹簧式的手按下去为低电平，手一松就变成了高电平。只要按一次松开后，模块就能自动输出一个低电平。（板子上的开关正常情况为高电平）

同时消抖部分在输入clk为50Mhz的时候可以延迟21ms来判断是否为开关按下-The module is based on verilog pulsed high-low to keep the trigger module includes both debounce function. Mainly on the development board for many of today' s switches are spring-loaded hand down low by the hand of a song becomes a high level. As long as the press release, the module will automatically output a low level. (Switch on the board is high normal) while the input debounce clk is 50Mhz part when you can delay 21ms to determine whether the switch is pressed