通过430f149单片机的ad采样，获得一个正弦波形的峰值数据，为了免去杂波干扰，多次采得峰值之后，取第三大的值，再取得平均数，是为比较合理的峰值数据。-By 430f149 SCM ad samples to get a sine wave peak data, for eliminating clutter, repeatedly mined after the peak, taking the third largest value, and then obtain the average