Basic concepts: clock cycle and machine cycle concepts of microcontroller

1. What is the clock cycle of 51 microcontroller?

Popular Science China: The clock cycle, also known as the oscillation cycle, is the cycle of the oscillation source that provides timing signals for the microcontroller. It is the most basic time unit of the microcontroller. When talking about the clock cycle, we must say that the crystal oscillator is the crystal oscillator. The crystal oscillator can be said to be the heart of the microcontroller. It provides a clock frequency fosc (oscillation frequency) for the microcontroller.

The so-called oscillation frequency (clock frequency) is naturally the number of times the crystal oscillator oscillates in one second. The higher the clock frequency, the faster the microcontroller runs, just like how many GHz a computer's CPU can accelerate to. The natural clock period Tosc=1/fosc.

For example, if the oscillation frequency of a microcontroller is 12MHz, fosc = 12MHz, then the oscillation period

Tosc = 1/fosc = 1/12us.

Chen: To put it bluntly, the reciprocal of the crystal oscillator is the clock cycle.

2. What is the machine cycle of 51 microcontroller?

51 It has a fixed machine cycle. One machine cycle contains six states, such as instruction fetch, memory read, memory write, etc. That is, the machine cycle is equal to 6 state cycles, and one state cycle is 2 clock cycles, so one machine cycle is equal to 12 clock cycles. Then the machine cycle of the microcontroller with a crystal oscillator frequency of 12MHz is T = 12*Tosc =1us