实现4种常见波形正弦、三角、锯齿、方波（A、B）的频率、幅度可控输出（方波

--A的占空比也是可控的），可以存储任意波形特征数据并能重现该波形，还可完成

--各种波形的线形叠加输出。

-4 sine wave to achieve common, triangle, sawtooth, square wave (A, B) the frequency and amplitude controlled output (square wave- A duty cycle is controllable), arbitrary waveform feature data can be stored and can re- is the waveform, it can perform- all kinds of linear superposition of the output waveform. 3 multi-function waveform generator