Timer1操作如果我的信号是低电平那实际的测量持续时间是？

我在这里读到的有点困惑，它在time1操作的数据表（PIC16F1937）中说：在计数器模式下，在第一个递增的上升沿之前，计数器必须注册一个下降沿…但是如果我的信号是低电平，实际上我在测量持续时间呢？下降沿的n？这意味着我会失去第一个脉冲吗？谢谢你的回复。



      以下为原文

    I am a little bit confused with what I read here, it says in the datasheet for the timer1 operation (PIC16f1937):

In Counter mode, a falling edge must be registered by the counter prior to the first incrementing rising edge...

But what if my signal is active low and I'm actually measuring the duration of the falling edge? Does that mean I will lose the first pulse? Thanks for the reply.