【MCU】Chapter 1: Understanding the structure of 8051 chip-EEWORLD

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1. Chip Introduction

Internal structure of single chip microcomputer

8 major components of 8051 microcontroller
1. CPU 2. RAM 3. ROM/EPROM/FLASH 4. Timer/Counter

5.Serial port 6.Four 8-bit parallel I/O ports 7.Special function registers 8.Interrupt system

There are 21 special function registers in 8051, 5 interrupt sources and 2 interrupt priority levels.

8051 is divided into: power pin, clock pin, I/O port pin, control pin

Use 1 to represent a high level and 0 to represent a low level

Control pins:
Pin 29: PSEN Read external memory selection signal, connected to the OE (output enable) terminal of the external memory
Pin 30: ALE/PROG Function 1. Address latch enable signal function 2. Burn input terminal
Pin 31: EA/Vpp 1. Internal/external memory selection controller. High: access internal storage. Low: external storage 2. When programming EPROM, programming voltage is required

2. Operation Circuit

MCU minimum system: including clock circuit and reset circuit

1. Clock circuit: internal clock vs external clock

The recommended crystal capacitors C1C2 are 30pF. Ceramic capacitors are 40pF

Connect from XTAL2 and ground XTAL1.

Clock cycle: refers to the time it takes for a crystal oscillator to complete one oscillation. 1 clock cycle = 1/(12x10^6)s, which is about 83.3ns

Machine cycle: refers to the time it takes for the CPU to complete a basic operation. One machine cycle contains 12 clock cycles.

Instruction cycle: refers to the time it takes for a microcontroller to execute an instruction.

2. Reset circuit

Apply a high level for 2 machine cycles on the RST pin to achieve reset

Keywords：MCU Reference address：【MCU】Chapter 1: Understanding the structure of 8051 chip

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Recommended ReadingLatest update time:2024-11-23 11:31

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