基于VHDL设计四个频率不同的呼吸灯，呼吸频率分别为 0.1Hz,0.2Hz，0.4Hz，0.8Hz

呼吸灯原理：利用PWM波控制led的亮度，的 原始代码 quartus软件亲测可用。-VHDL-based design in four different frequencies breathing light, breathing frequency was 0.1Hz, 0.2Hz, 0.4Hz, 0.8Hz breathing light principle: the use PWM to control the brightness led the wave, the source code is available quartus software pro-test.