基于80C51的增量型编码器计数器 ，因为编码器输入信号以作反相处理，因此若A相超前B相为正转，则A相下降沿时B相为高，否则则为反转-A relative to the falling edge of encoder input signal for inverting processing If A phase B, the forward-based the 80C51 incremental encoder counter B phase for high Otherwise, as compared to reversal