AT89C51英文数据手册：单片机功能与特性详解

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"AT89C51是一款与MCS-51产品兼容的低功耗、高性能CMOS 8位微计算机，内置4KB可编程并可擦除的闪存内存，支持0Hz到24MHz的全静态操作。它具有三级程序存储器锁定功能，128x8位内部RAM，32条可编程输入/输出线，两个16位定时器/计数器，六个中断源，可编程串行通道以及低功耗闲置和电源关闭模式。" 这篇文档详细介绍了AT89C51单片机的特性、引脚配置以及功能。AT89C51是基于Atmel的高密度非易失性存储技术制造的，它的核心特性包括： 1. **4KB In-System Reprogrammable Flash Memory**: 这意味着用户可以在系统中直接对这4KB的闪存进行编程和擦除，无需从设备中取出。它的写入/擦除耐久性达到1,000次循环，确保了长期使用的可靠性。 2. **Static Operation**: AT89C51能在0Hz至24MHz的频率范围内工作，这意味着它能在非常低的时钟频率下正常运行，适应各种不同的应用场景。 3. **Three-level Program Memory Lock**: 提供了三级程序存储器锁定功能，有助于保护程序代码不被非法访问或修改，增加了安全性。 4. **128x8-bit Internal RAM**: 内置128字节的随机访问内存，用于存储运行时的数据和变量。 5. **32 Programmable I/O Lines**: 包括P0、P1、P2和P3四个端口，每个端口有8条可编程的输入/输出线，总计32条，可以灵活配置以满足不同硬件接口需求。 6. **Two 16-bit Timer/Counters**: 提供两个16位的定时器/计数器，它们可以用于时间测量、定时触发和脉冲计数等功能。 7. **Six Interrupt Sources**: 包括RST（复位）、RXD（串行接收）、TXD（串行发送）、INT0、INT1、T0和T1等中断源，增强了实时处理能力。 8. **Programmable Serial Channel**: 可编程的串行通道支持UART（通用异步收发传输器）通信，可用于实现串行数据传输。 9. **Low-power Modes**: 包括Idle模式和Power-down模式，这两种低功耗模式在设备不活动时减少能耗，适合于电池供电或节能应用。引脚配置部分展示了AT89C51的物理布局，包括P0、P1、P2、P3端口，以及特殊功能引脚如RST（复位）、XTAL1和XTAL2（晶振输入）、EA/VPP（程序访问允许/编程电压）、ALE/PROG（地址锁存使能/编程脉冲）等，这些引脚的定义和功能对于正确连接和操作AT89C51至关重要。总体来说，AT89C51是一款广泛应用的8位微控制器，适用于各种嵌入式系统，如家用电器、工业控制、汽车电子、消费电子等领域，其丰富的功能和灵活性使其成为许多设计者的首选。

AT89C51

pulse is skipped during each access to external Data

Memory.

If desired, ALE operation can be disabled by setting bit 0 of

SFR location 8EH. With the bit set, ALE is active only dur-

ing a MOVX or MOVC instruction. Otherwise, the pin is

weakly pulled high. Setting the ALE-disable bit has no

effect if the microcontroller is in external execution mode.

PSEN

Program Store Enable is the read strobe to external pro-

gram memory.

When the AT89C51 is executing code from external pro-

gram memory, PSEN

is activated twice each machine

cycle, except that two PSEN

activations are skipped during

each access to external data memory.

/VPP

External Access Enable. EA must be strapped to GND in

order to enable the device to fetch code from external pro-

gram memory locations starting at 0000H up to FFFFH.

Note, however, that if lock bit 1 is programmed, EA

will be

internally latched on reset.

should be strapped to V

for internal program

executions.

This pin also receives the 12-volt programming enable volt-

age (V

) during Flash programming, for parts that require

12-volt V

XTAL1

Input to the inverting oscillator amplifier and input to the

internal clock operating circuit.

XTAL2

Output from the inverting oscillator amplifier.

Oscillator Characteristics

XTAL1 and XTAL2 are the input and output, respectively,

of an inverting amplifier which can be configured for use as

an on-chip oscillator, as shown in Figure 1. Either a quartz

crystal or ceramic resonator may be used. To drive the

device from an external clock source, XTAL2 should be left

unconnected while XTAL1 is driven as shown in Figure 2.

There are no requirements on the duty cycle of the external

clock signal, since the input to the internal clocking circuitry

is through a divide-by-two flip-flop, but minimum and maxi-

mum voltage high and low time specifications must be

observed.

Idle Mode

In idle mode, the CPU puts itself to sleep while all the on-

chip peripherals remain active. The mode is invoked by

software. The content of the on-chip RAM and all the spe-

cial functions registers remain unchanged during this

mode. The idle mode can be terminated by any enabled

interrupt or by a hardware reset.

It should be noted that when idle is terminated by a hard

ware reset, the device normally resumes program execu-

tion, from where it left off, up to two machine cycles before

the internal reset algorithm takes control. On-chip hardware

inhibits access to internal RAM in this event, but access to

the port pins is not inhibited. To eliminate the possibility of

an unexpected write to a port pin when Idle is terminated by

reset, the instruction following the one that invokes Idle

should not be one that writes to a port pin or to external

memory.

Figure 1. Oscillator Connections

Note: C1, C2 = 30 pF ± 10 pF for Crystals

= 40 pF ± 10 pF for Ceramic Resonators

XTAL2

GND

XTAL1

Status of External Pins During Idle and Power-down Modes

Mode Program Memory ALE PSEN PORT0 PORT1 PORT2 PORT3

Idle Internal 1 1 Data Data Data Data

Idle External 1 1 Float Data Address Data

Power-down Internal 0 0 Data Data Data Data

Power-down External 0 0 Float Data Data Data

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AT89C51英文数据手册：单片机功能与特性详解

AT89C51英文资料

AT89C51单片机数据手册

AT89C51中文资料手册，应该是官方版的，可以使用

AT89C51中文数据手册 pdf 高清版

AT89C51数据手册

AT89C51SND1芯片数据手册

英文版at89c52数据手册PDF

AT89C51中文资料手册

AT89C51 数据手册 英文版+中文版（软件翻译版本）

AT89C51官方数据手册：4K闪存与高级特性概览

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AT89C51 数据手册英文版+中文版（软件翻译版本）