What is MCU 89C51?

MCU 89C51, first of all, 51 series MCU, 89 stands for EEPROM (Electrically Erasable Program Memory). The most basic 51 single-chip microcomputer.

The understanding given to you by the single-chip microcomputer is the switch, each pin is a switch of 0 and 1, and the program is to control the pin output 0 or 1Or whether it is 0 or 1 to receive.

The single-chip microcomputer of CHMOS process developed with 8051 as the base core becomes the 80C51 series single-chip microcomputer, and the 89C51 is also developed based on the 8051 as the base core, so it is also the 80C51 series single-chip microcomputer, and the programming and other aspects are the same, with slight differences.

The architecture of 89c51 is a von Neumann structure:

The von Neumann structure's data bus and instruction bus are time-multiplexed, and on the same bus, sometimes data is transmitted and sometimes instructions, so it cannot take instructions and access data at the same time.

In the Haval structure, the program memory and data memory address codes are separated, so there are independent instruction buses and data buses. Access to instructions and access to data can be done at the same time.

First, the process is different.

1. MCS51 microcontroller: set ** processor, random access memory.

Read-only memory, various input and output ports, interrupt system, timer timer and other functions in one small and complete computer system.

C51 microcontroller: A low-finger lifting, high-performance CMOS 8-bit microprocessor with 4K bytes of flash programmable erasable read-only memory.

Second, the performance is different.

1. MCS51 microcontroller: 8051 is 4KBROM, 8751 is 4KBeProm, 8031 has no program storage on the chip, and 8951 is 4KBePROM. Other performance structures are identical, including 128B of on-chip memory and two 16-bit timers.

and 5 interrupt sources.

C51 microcontroller: Programmable serial channels, low-power idle and power-down modes, on-chip oscillator, and clock circuitry.

Third, the accessories are different.

The 89C51 also has an extra timer, so it can be said that the 89C51 is an enhanced version of the MCS51.

The minimum system circuit of 89C51 microcontroller mainly includes: power supply circuit, reset circuit and clock circuit.

1.Power circuits.

The power supply circuit is the power supply circuit of the single-chip microcomputer, generally or 5V, how much to refer to the working voltage of various types of single-chip microcomputer, usually 5V, which refers to the usual situation.

2.Reset circuit: including power-on reset and manual reset.

3.Clock circuitry.

The circuit used to cooperate with the external crystal to achieve oscillation, so that the single-chip microcomputer can provide a running clock, if the running clock is 0, the single-chip microcomputer will not work, of course, the clock that exceeds the working frequency of the single-chip microcomputer will also cause the single-chip microcomputer to not work.

At the moment of power-on, the voltage on the capacitor can not "jump", the voltage on the reset pull-down resistor is close to the power supply voltage, that is, the RST is high, the RST terminal voltage gradually decreases during the capacitor charging process, when the voltage on the RST terminal is less than a certain value, the CPU is out of the reset state.

Since the capacitor C1 is large enough, it can ensure that the active time of the RST high level is greater than 24 oscillation cycles, and the CPU can be reliably reset. The manual reset button is added to avoid being unable to reset reliably in the event of a crash. When the reset button is pressed, the capacitor C1 is discharged through R5.

When the capacitor C1 is discharged, the potential at the RST terminal is determined by the ratio of R1 to R2 partial voltage.

The 89C51 is a low-voltage, high-performance CMOS 8-bit microprocessor with 4K bytes of flash programmable and erasable read only memory. The erasable read-only memory of the microcontroller can be erased 1000 times.

The device is fabricated using Atmel's high-density nonvolatile memory fabrication technology and is compatible with the industry-standard MCS-51 instruction set and output pins.

Atmel's 89C51 is a high-efficiency microcontroller due to the combination of a versatile 8-bit CPU and flashing memory in a single chip, and the 89C2051 is a stripped-down version of it. The 89C microcontroller provides a flexible and inexpensive solution for many embedded control systems.