D/A转换是把数字量转换成模拟量的变换，从D/A输出的是模拟电压信号。产生锯齿波和三角波只需由A存放的数字量的增减来控制；要产生正弦波，较简单的手段是造一张正弦数字量表。取值范围为一个周期，采样点愈多，精度愈高些-D/A converter is to convert the analog digital transformation, from the D/A output is an analog voltage signal. Sawtooth and triangle wave generated by the A store only the amount of increase or decrease the number of control　to generate sine wave, is made simpler means of a sinusoidal digital scale. The range of a cycle, the more sampling points, the higher the accuracy of some