51单片机引脚（单片机2.2）

51单片机的引脚

51系列芯片存在两种封装结构：40只引脚的双列直插式和44只引脚方形扁平封装方式，我们主要介绍前者。40只引脚的双列直插式，简称DPI，主要有三类引脚：电源及晶振引脚（共4只）、控制引脚（共4只）、端口引脚（共32只）。

The 51 series chips have two package structures: a two-row in-line for 40 pins and a flat package for 44 pin squares, which we focus on. The 40-pin, two-row inline plug, or DPI, consists of three main types of pins: power supply and crystal pins (4 in total), control pins (4 total), and port pins (32 total).

各接口的组成和作用

1.电源及晶振。电源由高电平端口和低电平端口组成，Vcc（40脚）接+5V高电平，Vss（20脚）接地低电平；XTAL1/2（19/18脚）分别为外接晶振引脚,前者为内置放大器输入端，后者为内置放大器输出端。

2.控制引脚。控制引脚共有四个，每一个功能皆是不同的，并且同一个引脚存在多种功能，同时，因为高低电平不同，功能也有所不同。RST/VPD (9)可用于复位/ 备用电源引脚；ALE/PROG (30)用于地址锁存使能输出/ 编程脉冲输入；PSEN (29)用于输出访问外部ROM读选通信号；EA/ VPP (31)用于外部ROM允许访问/ 编程电源输入。

3.端口引脚存在4组，每组8只，是单片机重要的对外联络通道。每组名称为：P0、P1、P2、P3，如P0接口为：P0.0~P0.7。

1. Power supply and crystal. The power supply consists of a high-level port and a low-level port, with Vcc (40 feet) connected to the 5V high level, vss (20 feet) grounded at a low level, and XTAL1/2 (19/18 feet) as the external crystal pin, the former as the built-in amplifier input and the latter as the built-in amplifier output.

2. Control the pin. There are four control pins, each with different functions, and the same pin has multiple functions, and because the levels are different, the functions are different. RST/VPD (9) can be used for reset/back-up power pins, ALE/PROG (30) for address latch enable output/programming pulse inputs, PSEN (29) for output access to external ROM read-select communication numbers, and EA/VPP (31) for external ROM allow access/programming power inputs.

3. There are 4 groups of port pins, each group of 8, is an important external contact channel of the microcontroller. Each group name is: P0, P1, P2, P3, such as P0 interface is: P0.0 to P0.7.

参考资料：百度

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文案|李恒宇

排版|李恒宇

审核|李小雪