Introduction of single-chip microcomputer (I.)

First, bus

A bus is a public channel that transmits information between parts of a computer. There are two kinds of internal bus and external bus in microcomputer. The internal bus is the connection between the internal CPUs. The external bus refers to the connection between the CPU and other components.

There are three types of external bus: Data bus, address bus ab (address bus), control bus CB.

Second, the basic timing

(1) Oscillation period: Also known as the Always cycle, is to provide a single-chip microcomputer clock pulse signal oscillation source period, the Development Board is 12MHZ.

(2) The state period: Each state period is twice times the clock period, is the oscillation period after the second frequency.

(3) Machine cycle: A machine cycle consists of 6 status cycle S1-S6, which is 12 clock cycles. Within a machine cycle, the CPU can perform a separate operation.

(4) instruction cycle: It is the full time that the CPU takes to complete an operation. Each instruction execution time is composed of one or several machine cycles. In the MCS-51 system, there are single-cycle instructions, dual-cycle instructions, and four-period directives.

Introduction of single-chip microcomputer (I.)