The host changes the data line only when the Clock line is low, and data is read by the device when Clock is high.

只有当时钟线为低的时候，主机才可以改变数据线(也就是将数据写入到数据线)。数据将在时钟为高电平的时候被设备读龋。

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The host has ultimate control over the bus and may inhibit communication at any time by pulling the Clock line low.

主机对总线有最高的控制权，在任何时候通过将时钟线拉低就可以禁止通信。

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When the keyboard or mouse wants to send information, it first checks the Clock line to make sure it's at a high logic level.

当键盘或者鼠标想发送数据时，它首先必须检查时钟线，确认它处于高电平。

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Mr. SAMUEL STATLAND (Polling volunteer): If you're in line at 8 o'clock and are identified as being in line at 8 o'clock, you will vote on the touch screen machines.

NPR: For Santorum, Race Momentum Swings

Her official race photos show her beneath a finish line clock that reads 4:09:29.

NPR: The Finish Line: What The Bombing Was Like

One employee, Silvia Hernandez, recounted how she was finishing up her workday at another building and standing in line to clock out when she heard a blast.

CNN: February 1, 2013 -- Updated 1937 GMT (0337 HKT)