使用vhdl语言在quatus上编写自定义元件，用原理图实现了蜂鸣器按照音阶一秒换一个音进行循环发声，系统时钟为20m。(Using the VHDL language to write a custom component on the quatus, the buzzer is used to make a circular sound in one second of the phonetic scale, and the system clock is 20m.)