The clock cycle, also known as the oscillation cycle, is defined as the reciprocal of the clock pulse (it can be understood that the clock cycle is the reciprocal of the external crystal oscillator of the single chip microcomputer, such as the 12m crystal oscillator, whose time cycle is 1 / 12 US). It is the most basic and smallest time unit in the computer.

How to define the clock cycle in single chip microcomputer

In one clock cycle, the CPU only completes one basic action. For a single chip microcomputer, if the clock frequency of 1MHz is adopted, the clock cycle is 1US; If 4MHz clock frequency is adopted, the clock cycle is 250us. Because the clock pulse is the basic working pulse of the computer, it controls the working rhythm of the computer (unifying each step of the computer to its pace). Obviously, for the same type of computer, the higher the clock frequency, the faster the computer will work. However, because different computer hardware circuits and devices are not exactly the same, the required clock cycle frequency range is not necessarily the same. The clock range of 8051 single chip microcomputer we studied is 1.2mhz-12mhz.

In 8051 single chip microcomputer, a clock cycle is defined as a beat (represented by P), and two beats are defined as a state cycle (represented by s). Please refer to the following sequence diagram.

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