Digital Signals Arrive on Time

摘要

Clock signals comprise rising edges (logic-low to logic-high transitions), and falling edges (logic-high to logic-low transitions). A clock signal can exist as square waves with a regular period and duty cycle or as a continuous series of periodic pulses. The latter type of signal can trigger a latch to accept data, interrupt a microcontroller, and so on. Regular clock waveforms govern the timing of microprocessor-based controllers, communication systems, memory chips, and other devices that perform operations at regular intervals. Depending on the clocked device, either, a rising or a falling clock-signal edge causes an action. A device such as a double data-rate (DDR) memory uses both clock edges to trigger actions.