If the host pulls clock low before the first high-to-low clock transition, or after the falling edge of the last clock pulse, the keyboard/mouse does not need to retransmit any data.

• 如果在第一个高->低时钟跳变时，（或者在最后一个时钟脉冲的下降沿之后）主机将时钟拉低，键盘/鼠标不必重新传输任何数据。