at89c52中文资料介绍

at89c52单片机简介中英文对照外文翻译文献中英文资料对照外文翻译A T89C52 Single-chip microprocessor introductionSelection of Single-chip microprocessor1. Development of Single-chip microprocessorThe main component part of Single-chip microprocessor as a result of by such centralize to be living to obtain on the chip，In immediate future middle processor CPU。

Storage RAM immediately﹑memoy read ROM﹑Interrupt system、Timer /'s counter along with I/O's rim electric circuit awaits the main microcomputer section，The lumping is living on the chip。

Although the Single-chip microprocessor r is only a chip，Yet through makes up and the meritorous service be able to on sees，It had haveed the calculating machine system property，calling it for this reason act as Single-chip microprocessor r minisize calculating machine SCMS and abbreviate the Single-chip microprocessor。

51单片机AT89C52中文资料--------------------------------------------------------------------------------51单片机AT89C52中文资料AT89C52 ATMEL公司生产的低电压，高性能CMOS 8位单片机．片内含8K byTES的可反复擦写的只读程序存储器（PEROM）和256 byTES 。

的随机存取数据存储器（RAM），器件采用ATMEL公司的高密度、非易失性存储技术生产，与标准MCS-51指令系统及8052 产品引脚兼容，片内置通用8位中央处理器（CPU ）和FLASH由存储单元，功能强大AT89C52单片适用于许多较为复杂控制应用场合。

主要性能参数：与Mcs-51产品指令和引脚完全兼容。

8字节可重擦写FLASH闪速存储器1000 次擦写周期全静态操作：0HZ-24MHZ三级加密程序存储器256X8字节内部RAM32个可编程I/0口线3个16 位定时／计数器8个中断源可编程串行UART通道低功耗空闲和掉电模式内部结构图AT89C52内部框图功能特性：AT89C52 提供以下标准功能：8字节FLASH闪速存储器，256字竹内部RAM , 32个I/O口线，3个16 位定时／计数器，一个6向量两级中断结构，一个全双工串行通信口，片内振荡器及时钟电路。

同时，AT89c52可降至OHz的静态逻辑操作，并支持两种软件可选的节电上作模式。

空闲方式停止CPU 的工作，但允许RAM，定时／计数器．串行通信口及中断系统继续工作。

掉电方式保存RAM 中的内容，但振荡器停止工作并禁止其它所有部件工作直到下一个硬件复位.功能引脚说明：Vcc:电源电压GND:地P0：P0口是一组8位漏极开路型双向1/O 口，也即地址/数据总线复用口。

作为输出口用时．每位能吸收电流的方式驱动8个TTL 逻辑门电路，对端口P0 写“1”时，可作为高阻抗输入端用。

AT89C52中文资料AT89C52的中文资料AT89C52是美国Atmel公司生产的低电压、高性能CMOS 8位单片机，片内含8KB的可反复檫写的程序存储器和12B的随机存取数据存储器（RAM），器件采用Atmel公司的高密度、非易失性存储技术生产，兼容标准MCS-51指令系统，片内配置通用8位中央处理器（CPU）和Flash存储单元，功能强大的AT89C52单片机可灵活应用于各种控制领域。

AT89C52单片机属于AT89C51单片机的增强型，与Intel 公司的80C52在引脚排列、硬件组成、工作特点和指令系统等方面兼容。

其主要工作特性是：片内程序存储器内含8KB的Flash程序存储器，可擦写寿命为1000次；片内数据存储器内含256字节的RAM；具有32根可编程I/O口线；具有3个可编程定时器；中断系统是具有8个中断源、6个中断矢量、2个级优先权的中断结构；串行口是具有一个全双工的可编程串行通信口；具有一个数据指针DPTR；低功耗工作模式有空闲模式和掉电模式；具有可编程的3级程序锁定位；AT89C52工作电源电压为5（1+0.2）V，且典型值为5V；AT89C52最高工作频率为24MHz。

单片机正常工作时，都需要有一个时钟电路和一个复位电路。

本设计中选择了内部时钟方式和按键电平复位电路，来构成单片机的最小电路。

如图3.1所示。

功能特性描述AT89S52是一种低功耗、高性能CMOS8位微控制器，具有8K 在系统可编程Flash 存储器。

使用Atmel 公司高密度非易失性存储器技术制造，与工业80C51 产品指令和引脚完全兼容。

片上Flash允许程序存储器在系统可编程，亦适于常规编程器。

在单芯片上，拥有灵巧的8 位CPU 和在系统可编程Flash，使得AT89S52为众多嵌入式控制应用系统提供高灵活、超有效的解决方案。

AT89S52具有以下标准功能：8k字节Flash，256字节RAM，32 位I/O 口线，看门狗定时器，2 个数据指针，三个16 位定时器/计数器，一个6向量2级中断结构，全双工串行口，片内晶振及时钟电路。

AT89C52概述AT89C52是一款高性能的8位单片机，由Atmel公司生产。

它是AT89系列单片机中的一员，采用MCS-51指令集架构，并使用快速闪存储存程序。

AT89C52具有丰富的外设，包括多个输入输出引脚、计时器、串口通信接口等，广泛应用于嵌入式系统、通信设备、工业控制等领域。

主要特性•采用CMOS技术，工作电压范围广泛（2.4V至5.5V）•具有8KB的内部闪存，用于存储程序和数据•提供256字节的内部RAM，可用于数据存储•包含三个计时器/计数器，可用于定时/计数功能•集成两个串口通信接口，方便与外部设备进行数据交互•支持多种中断方式，提供更好的系统响应能力•可编程输入/输出引脚，可用于连接外部设备引脚描述AT89C52具有40个引脚，以下是一些重要引脚的描述：1.P1.0至P1.7: 8位并行输入/输出引脚，可根据需要进行配置。

在配置为输入时，可以连接外部设备并读取输入值；在配置为输出时，可以向外部设备发送数据。

2.P2.0至P2.7: 8位并行输入/输出引脚，也可以根据需要进行配置。

3.P3.0至P3.7: 8位并行输入/输出引脚，同时具有更多功能，包括与外部存储器的数据和地址传输，以及与LCD显示器的连接等。

4.RST: 复位引脚，将其拉低时可以重启单片机。

5.EA/VPP: 外部访问使能/编程电压引脚，可用于提供外部程序存储器的访问或编程电压。

6.XTAL1/XTAL2: 外部晶振引脚，接入适当的晶振电路以提供时钟信号。

闪存编程AT89C52的程序存储在内部闪存中。

要编程AT89C52，可以使用专用的编程器，通过并行端口或串行端口将目标程序下载到芯片中。

编程AT89C52的一般步骤如下：1.选择所需的编程器，并连接到AT89C52的编程接口。

2.打开编程器软件，并选择正确的单片机型号。

3.导入目标程序文件，该文件应该是以二进制格式存储的。

4.配置编程器选项，包括芯片复位方式、编程电压等。

at89c52单片机引脚说明
,AT89C52高性能8位单片机
at89c52单片机引脚说明,AT89C52高性能8位单片机
AT89C52引脚图
AT89C52是一个低电压，高性能CMOS 8位单片机，片内含8k bytes的可反复擦写的Flash只读程序存储器和256 bytes的随机存取数据存储器（RAM），器件采用ATMEL公司的高密度、非易失性存储技术生产，兼容标准MCS-51指令系统，片内置通用8位中央处理器和Flash存储单元，功能强大的AT89C52单片机可为您提供许多较复杂系统控制应用场合。

AT89C52有40个引脚，32个外部双向输入/输出（I/O）端口，同时内含2个外中断口，3个16位可编程定时计数器,2个全双工串行通信口，2个读写口线，AT89C52可以按照常规方法进行编程，也可以在线编程。

其将通用的微处理器和Flash存储器结合在一起，特别是可反复擦写的Flash存储器可有效地降低开发成本。

AT89C52有PDIP、PQFP/TQFP及PLCC等三种封装形式，以适应不同产品的需求。

主要功能特性：
·兼容MCS51指令系统·8k可反复擦写(>1000次）Flash ROM
·32个双向I/O口·256x8bit内部RAM
·3个16位可编程定时/计数器中断·时钟频率0-24MHz
·2个串行中断·可编程UART串行通道
·2个外部中断源·共6个中断源
·2个读写中断口线·3级加密位
·低功耗空闲和掉电模式·软件设置睡眠和唤醒功能
1/ 1。

AT89C52单片机介绍在众多的单片机系列中，AT89C52是一种低功耗、高性能CMOS8位微控制器，具有8K在系列可编程Flash存储器。

使用Atmel公司高密度非易失性存储器技术制造，与工业80C51产品指令和引脚完全兼容。

片上Flash允许程序存储器在系统可编程，也适用于常规编程。

在单芯片上，拥有灵巧的8位CPU和在系统可编程Flash，使得AT89C52为众多嵌入式控制应用系统提供高灵活、超高效的解决方案。

AT89C52具有以下标准功能：8K字节Flash，256字节RAM，32位I/O口线，3个16位定时器/计数器，一个响亮2级中断结构，全双工串行口，片内晶振及时钟电路。

另外，AT89C52可降至0HZ静态逻辑操作，支持2种软件可选择节电模式。

空闲模式下，CPU停止工作，允许RAM、定时器/计数器、串口、中断继续工作。

掉电保护方式下，RAM内容被保存，振荡器被冻结，单片机一切工作停止，直到下一个中断或硬件复位为止。

AT89C52单片机为很多嵌入式控制系统提供了一种灵活性高且廉价的方案。

故此选用AT89C52单片机。

1 AT89C52单片机1.1 AT89C52单片机的硬件结构如图3-1所示，为AT89C52的硬件结构图。

AT89C52单片机的内部结构与MCS-51系列单片机的构成基本相同。

CPU是由运算器和控制器所构成的。

运算器主要用来对操作数进行算术、逻辑运算和位操作的。

控制器是单片机的指挥控制部件，主要任务的识别指令，并根据指令的性质控制单片机各功能部件，从而保证单片机各部分能自动而协调地工作。

它的程序存储器为8K字节可重擦写Flash闪速存储器，闪烁存储器允许在线+5V电擦除、电写入或使用编程器对其重复编程。

数据存储器比51系列的单片机相比大了许多为256字节RAM。

AT89C52单片机的指令系统和引脚功能与MCS-51的完全兼容。

图 3-1 单片机89C52结构框图1.2 主要性能参数• 8K字节可重擦写Flash闪速存储器• 1000次可擦写周期•全静态操作：0Hz-24MHz•三级加密程序存储器• 256×8字节内部RAM• 32个可编程I/O口线• 3个16位定时/计数器• 8个中断源•可编程串行UART通道•低功耗空闲和掉电模式图 3-2 AT89C52外部引脚图1.3 AT89C52管脚说明VCC：电源GND：接地P0口：P0口是一个8位漏级开路的双向I/O口。

外文翻译--AT89C52单片机的介绍外文翻译AT89C52 单片机的介绍AT89C52 单片机是一款广泛应用于各种电子设备中的微控制器。

它具有高性能、低功耗、易于编程等优点，为许多电子项目的实现提供了强大的支持。

AT89C52 单片机拥有丰富的内部资源。

它包含 8KB 的可重复编程的 Flash 存储器，用于存储程序代码。

这使得开发者可以方便地修改和更新程序，而无需更换硬件。

此外，它还有 256 字节的内部 RAM，用于数据的临时存储和处理。

在处理能力方面，AT89C52 单片机采用了 8 位的中央处理器（CPU），工作频率可达 24MHz。

虽然相比于现代的高性能处理器，它的处理速度不算快，但对于许多简单的控制任务和实时性要求不高的应用来说，已经足够胜任。

例如，在一些小型的家电控制、简单的测量仪器以及玩具等产品中，AT89C52 单片机能够准确、稳定地执行控制逻辑。

该单片机的引脚功能也十分丰富。

它通常具有 40 个引脚，包括电源引脚、时钟引脚、复位引脚以及多个输入输出引脚。

电源引脚用于提供单片机正常工作所需的电压，一般为 5V。

时钟引脚则连接外部晶振，为单片机提供工作时钟。

复位引脚用于系统的初始化和异常情况下的恢复。

而众多的输入输出引脚可以配置为不同的工作模式，如输入模式用于接收外部信号，输出模式用于控制外部设备。

在编程方面，AT89C52 单片机支持多种编程语言，如汇编语言和 C 语言。

汇编语言虽然编写较为复杂，但执行效率高；C 语言则更易于理解和编写，适合较大规模的程序开发。

通过专门的编程工具，如Keil C51 等，可以将编写好的程序下载到单片机中，实现特定的功能。

AT89C52 单片机在通信方面也具备一定的能力。

它可以通过串行通信接口（UART）与其他设备进行数据交换。

这种通信方式在与计算机、传感器、显示屏等外部设备连接时非常有用。

例如，在数据采集系统中，单片机可以通过 UART 接口将采集到的数据发送给计算机进行进一步处理和分析。

AT89C52单片机介绍
AT89C52是Atmel公司生产的一款经典的8位单片机。

它采用MCS-51系列内核，具有高性能、低功耗和强大的外设功能。

AT89C52是AT89C51的改进版本，具有更高的运行速度和更大的存储空间。

首先，AT89C52采用了高性能的CMOS技术，工作频率高达40MHz，可以实现高效的数据处理和实时控制。

与普通的单片机相比，它具有更快的响应速度和更高的运算能力，可以满足复杂控制系统的要求。

其次，AT89C52具有8KB的内部闪存程序存储器，可以存储用户编写的程序代码。

它还具有256字节的RAM内存和128个IO口，可用于连接各种外部设备和传感器。

此外，AT89C52还支持多种通信接口，如UART、SPI和I2C，方便与其他设备进行数据交换和通信。

此外，AT89C52还具有丰富的开发资源和工具支持。

Atmel公司提供了一套完整的开发套件，包括编译器、调试器和仿真器等，为用户提供方便和高效的开发环境。

并且，AT89C52的软件编程接口也非常友好，可以使用C语言或汇编语言进行编程，灵活性很高。

总之，AT89C52是一款功能强大、性能稳定的8位单片机。

它具有高速运算能力、丰富的外设功能和灵活的IO口控制。

它可以广泛应用于各种控制系统、仪器仪表、家电和智能设备等领域。

同时，它的开发环境和编程接口也很友好，为用户提供了方便和高效的开发工具。

AT89C52 DatasheetsFeatures• Compatible with MCS-51™ Products• 8K Bytes of In-System Reprogrammable Flash Memory–Endurance: 1,000 Write/Erase Cycles• Fully Static Operation: 0 Hz to 24 MHz• Three-Level Program Memory Lock• 256 x 8-Bit Internal RAM• 32 Programmable I/O Lines• Three 16-Bit Timer/Counters• Eight Interrupt Sources• Programmable Serial Channel• Low Power Idle and Power Down ModesDescriptionThe AT89C52 is a low-power, high-performance CMOS 8-bit microcomputer with 8K bytes of Flash programmable and erasable read only memory (PEROM). The device is manufactured using Atmel’s high density nonvolatile memory technology and is compatible with the industry standard 80C51 and 80C52 instruction set and pinout.The on-chip Flash allows the program memory to be reprogrammed in-system or by a conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel AT89C52 is a powerful microcomputer which provides a highly flexible and cost effective solution to many embedded control applications.The AT89C52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM,32 I/O lines, three 16-bit timer/counters, a six-vector two-level interrupt architecture,a full duplex serial port, on-chip oscillator, and clock circuitry.In addition, the AT89C52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters,serial port, and interrupt system to continue functioning.The Power Down Mode saves the RAM contents but freezes the oscillator, disabling all other chip functions until the next hardware reset.Pin DescriptionVCCSupply voltage.GNDGround.Port 0Port 0 is an 8-bit open drain bidirectional I/O port. As an output port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can be used as highimpedance inputs. Port 0 can also be configured to be the multiplexed loworder address/data bus during accesses to external program and data memory. In this mode, P0 has internal pullups.Port 0 also receives the code bytes during Flash programming and outputs the code bytes during program verification. External pullups are required during program verification.Port 1Port 1 is an 8-bit bidirectional I/O port with internal pullups.The Port 1 output buffers can sink/source four TTL inputs.When 1s are written to Port 1 pins, they are pulled high by the internal pullups and can be used as inputs. As inputs,Port 1 pins that are externally being pulled low will source current (IIL) because of the internal pullups.In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external count input (P1.0/T2) and thetimer/counter 2 trigger input (P1.1/T2EX), respectively, as shown in the following table.Port 1 also receives the low-order address bytes during Flash programming and verification. Port 2Port 2 is an 8-bit bidirectional I/O port with internal pullups.The Port 2 output buffers can sink/source four TTL inputs.When 1s are written to Port 2 pins, they are pulled high by the internal pullups and can be used as inputs. As inputs,Port 2 pins that are externally being pulled low will source current (IIL) because of the internal pullups.Port 2 emits the high-order address byte during fetches from external program memory and during accesses to external data memory that use 16-bit addresses. In this application, Port 2 uses strong internal pull-ups when emitting 1s. During accesses to external data memory that use 8-bit addresses, Port 2 emits the contents of the P2 Special Function Register.Port 2 also receives the high-order address bits and some control signals during Flash programming and verification.Port 3Port 3 is an 8-bit bidirectional I/O port with internal pullups.The Port 3 output buffers can sink/source four TTL inputs.When 1s are written to Port 3 pins, they are pulled high by the internal pullups and can be used as inputs. As inputs,Port 3 pins that are externally being pulled low will source current (IIL) because of the pullups. Port 3 also serves the functions of various special features of the AT89C51, as shown in the following table.Port 3 also receives some control signals for Flash programming and verification.RSTReset input. A high on this pin for two machine cycles while the oscillator is running resets the device.ALE/PROGAddress Latch Enable is an output pulse for latching the low byte of the address during accesses to external memory.This pin is also the program pulse input (PROG) duringFlash programming.In normal operation, ALE is emitted at a constant rate of 1/6 the oscillator frequency and may be used for external timingor clocking purposes. Note, however, that one ALE 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 during 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.PSENProgram Store Enable is the read strobe to external program memory.When the AT89C52 is executing code from external program memory, PSEN is activated twice each machine cycle, except that two PSEN activations are skipped during each access to external data memory. External Access Enable. EA must be strapped to GND in order to enable the device to fetch code from external program memory locations starting at 0000H up to FFFFH.Note, however, that if lock bit 1 is programmed, EA will be internally latched on reset.EA should be strapped to VCC for internal program executions.This pin also receives the 12-volt programming enable voltage(VPP) during Flash programming when 12-volt programmingis selected.XTAL1Input to the inverting oscillator amplifier and input to the internal clock operating circuit.XTAL2Output from the inverting oscillator amplifier.Special Function RegistersA map of the on-chip memory area called the Special Function Register (SFR) space is shown in Table 1. Note that not all of the addresses are occupied, and unoccupied addresses may not be implemented on the chip. Read accesses to these addresses will in general return random data, and write accesses will have an indeterminate er software should not write 1s to these unlisted locations,since they may be used in future products to invoke new features. In that case, the reset or inactive values of the new bits will always be 0.Timer 2 Registers: Control and status bits are contained in registers T2CON (shown in Table 2) and T2MOD (shown in Table 4) for Timer 2. The register pair (RCAP2H, RCAP2L) are the Capture/Reload registers for Timer 2 in 16-bit capture mode or 16-bit auto-reload mode. Interrupt Registers: The individual interrupt enable bits are in the IE register. Two priorities can be set for each of the six interrupt sources in the IP register.Data MemoryThe AT89C52 implements 256 bytes of on-chip RAM. The upper 128 bytes occupy a parallel address space to the Special Function Registers. That means the upper 128 bytes have the same addresses as the SFR space but are physically separate from SFR space.When an instruction accesses an internal location above address 7FH, the address mode used in the instruction specifies whether the CPU accesses the upper 128 bytes of RAM or the SFR space. Instructions that use direct addressing access SFR space.For example, the following direct addressinginstruction accesses the SFR at location 0A0H (which is P2).Instructions that use indirect addressing access the upper 128 bytes of RAM. For example, the following indirect addressing instruction, where R0 contains 0A0H, accesses the data byte at address 0A0H, rather than P2 (whose address is 0A0H).Note that stack operations are examples of indirect addressing, so the upper 128 bytes of data RAM are available as stack space.Timer 0 and 1Timer 0 and Timer 1 in the AT89C52 operate the same way as Timer 0 and Timer 1 in the AT89C51.Timer 2Timer 2 is a 16-bit Timer/Counter that can operate as either a timer or an event counter. The type of operation isselected by bit C/T2 in the SFR T2CON (shown in Table 2). Timer 2 has three operating modes: capture, auto-reload (up or down counting), and baud rate generator. The modes are selected by bits in T2CON, as shown in Table 3.Timer 2 consists of two 8-bit registers, TH2 and TL2. In the Timer function, the TL2 register is incremented every machine cycle. Since a machine cycle consists of 12 oscillator periods, the count rate is 1/12 of the oscillator frequency.In the Counter function, the register is incremented in response to a 1-to-0 transition at its corresponding external input pin, T2. In this function, the external input is sampled during S5P2 of every machine cycle. When the samples show a high in one cycle and a low in the next cycle, the count is incremented. The new count value appears in the register during S3P1 of the cycle following the one in which the transition was detected. Since two machine cycles (24 oscillator periods) are required to recognize a 1-to-0 transition, the maximum count rate is 1/24 of the oscillator frequency.To ensure that a given level is sampled at least once before it changes, the level should be held for at least one full machine cycle.Capture ModeIn the capture mode, two options are selected by bit EXEN2 in T2CON. If EXEN2 = 0, Timer 2 is a 16-bit timer or counter which upon overflow sets bit TF2 in T2CON. This bit can then be used to generate an interrupt. If EXEN2 = 1, Timer 2 performs the same operation, but a 1-to-0 transition at external input T2EX also causes the current value in TH2 and TL2 to be captured into RCAP2H and RCAP2L, respectively. In addition, the transition at T2EX causes bit EXF2 in T2CON to be set. The EXF2 bit, like TF2, can generate an interrupt. The capture mode is illustrated in Figure 1.Auto-Reload (Up or Down Counter)Timer 2 can be programmed to count up or down when configured in its 16-bit auto-reload mode. This feature is invoked by the DCEN (Down Counter Enable) bit located in the SFR T2MOD (see Table 4). Upon reset, the DCEN bit is set to 0 so that timer 2 will default to count up. When DCEN is set, Timer 2 can count up or down, depending on the value of the T2EX pin.Figure 2 shows Timer 2 automatically counting up when DCEN = 0. In this mode, two options are selected by bit EXEN2 in T2CON. If EXEN2 = 0, Timer 2 counts up to 0FFFFH and then sets the TF2 bit upon overflow. The overflow also causes the timer registers to be reloaded with the 16-bit value in RCAP2H and RCAP2L. The values in Timer in Capture ModeRCAP2H and RCAP2L are preset by software. If EXEN2 = 1, a 16-bit reload can be triggered either by an overflow or by a 1-to-0 transition at external input T2EX. This transition also sets the EXF2 bit. Both the TF2 and EXF2 bits can generate an interrupt if enabled. Setting the DCEN bit enablesTimer 2 to count up or down, as shown in Figure 3. In this mode, the T2EX pin controls the direction of the count. A logic 1 at T2EX makes Timer 2 count up. The timer will overflow at 0FFFFH and set the TF2 bit. This overflow also causes the 16-bit value in RCAP2H and RCAP2L to be reloaded into the timer registers, TH2 and TL2, respectively. A logic 0 at T2EX makes Timer 2 count down. The timer underflows when TH2 and TL2 equal the values stored in RCAP2H and RCAP2L. The underflow sets the TF2 bit and causes 0FFFFH to be reloaded into the timer registers. The EXF2 bit toggles whenever Timer 2 overflows or underflows and can be used as a 17th bit of resolution. In this operating mode, EXF2 does not flag an interrupt.Baud Rate GeneratorTimer 2 is selected as the baud rate generator by setting TCLK and/or RCLK in T2CON (Table 2). Note that the baud rates for transmit and receive can be different if Timer 2 is used for the receiver or transmitter and Timer 1 is used for the other function. Setting RCLK and/or TCLK puts Timer 2 into its baud rate generator mode, as shown in Figure 4.The baud rate generator mode is similar to the auto-reload mode, in that a rollover in TH2 causes the Timer 2 registersto be reloaded with the 16-bit value in registers RCAP2H and RCAP2L, which are preset by software.The baud rates in Modes 1 and 3 are determined by TimerThe Timer can be configured for either timer or counter operation. In most applications, it is configured for timer operation (CP/T2 = 0). The timer operation is different for Timer 2 when it is used as a baud rate generator. Normally, as a timer, it increments every machine cycle (at 1/12 the oscillator frequency). As a baud rate generator, however, it increments every state time (at 1/2 the oscillator frequency).where (RCAP2H, RCAP2L) is the content of RCAP2H and RCAP2L taken as a 16-bit unsigned integer. Timer 2 as a baud rate generator is shown in Figure 4. This figure is valid only if RCLK or TCLK = 1 in T2CON. Note that a rollover in TH2 does not set TF2 and will not generate an interrupt. Note too, that if EXEN2 is set, a 1-to-0 transition in T2EX will set EXF2 but will not cause a reload from (RCAP2H, RCAP2L) to (TH2, TL2). Thus when Timer 2 is in use as a baud rate generator, T2EX can be used as an extra external interrupt.Note that when Timer 2 is running (TR2 = 1) as a timer in the baud rate generator mode, TH2 or TL2 should not be read from or written to. Under these conditions, the Timer is incremented every state time, and the results of a read or write may not be accurate. The RCAP2 registers may be read but should not be written to, because a write might overlap a reload and cause write and/or reload errors. The timer should be turned off (clear TR2) before accessing the Timer 2 or RCAP2 registers. Programmable Clock OutA 50% duty cycle clock can be programmed to come out on P1.0, as shown in Figure 5. This pin, besides being a regular I/O pin, has two alternate functions. It can be programmedto input the external clock for Timer/Counter 2 or to output a 50% duty cycle clock ranging from 61 Hz to 4 MHz at a 16 MHz operating frequency. To configure the Timer/Counter 2 as a clock generator, bit C/T2 (T2CON.1) must be cleared and bit T2OE (T2MOD.1) must be set. Bit TR2 (T2CON.2) starts and stops the timer. The clock-out frequency depends on the oscillator frequency and the reload value of Timer 2 capture registers (RCAP2H, RCAP2L),In the clock-out mode, Timer 2 roll-overs will not generate an interrupt. This behavior is similar to when Timer 2 is used as a baud-rate generator. It is possible to use Timer 2 as a baud-rate generator and a clock generator simultaneously. Note, however, that the baud-rate and clock-out frequencies cannot be determined independently from one another since they both use RCAP2H and RCAP2L.UARTThe UART in the AT89C52 operates the same way as the UART in the AT89C51.InterruptsThe AT89C52 has a total of six interrupt vectors: two external interrupts (INT0 and INT1), three timer interrupts (Timers 0, 1, and 2), and the serial port interrupt. These interrupts are all shown in Figure 6.Each of these interrupt sources can be individually enabled or disabled by setting or clearing a bit in Special Function Register IE. IE also contains a global disable bit, EA, which disables all interrupts at once. Note that Table 5 shows that bit position IE.6 is unimplemented. In the AT89C51, bit position IE.5 is also unimplemented. User software should not write 1s to these bit positions, since they may be used in future AT89 products. Timer 2 interrupt is generated by the logical OR of bits TF2 and EXF2 in register T2CON. Neither of these flags is cleared by hardware when the service routine is vectored to. In fact, the service routine may have to determine whether it was TF2 or EXF2 that generated the interrupt, and that bit will have to be cleared in software. The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the cycle in which the timers overflow. The values are then polled by the circuitry in the next cycle. However,the Timer 2 flag, TF2, is set at S2P2 and is polled in the same cycle in which the timer overflows.Oscillator CharacteristicsXTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier that can be configured for use as an on-chip oscillator, as shown in Figure 7. 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 8. 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 maximum voltage high and low time specifications must be observed.Idle ModeIn idle mode, the CPU puts itself to sleep while all the onchip peripherals remain active. The mode is invoked by software. The content of the on-chip RAM and all the special functions registers remain unchanged during this mode. The idle mode can be terminated by any enabled interrupt or by a hardware reset. Note that when idle mode is terminated by a hardware reset, the device normally resumes program execution 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 mode is terminated by a reset, the instruction following the one that invokes idle mode should not write to a port pin or to external memory.Power Down ModeIn the power down mode, the oscillator is stopped, and the instruction that invokes power down is the last instruction executed. The on-chip RAM and Special Function Registersretain their values until the power down mode is terminated. The only exit from power down is a hardware reset. Reset redefines the SFRs but does not change the on-chip RAM. The reset should not be activated before VCC is restored to its normal operating level and must be held active long enough to allow the oscillator to restart and stabilize.Program Memory Lock BitsThe AT89C52 has three lock bits that can be left unprogrammed (U) or can be programmed (P)to obtain the additional features listed in the following table. When lock bit 1 is programmed, the logic level at the EA pin is sampled and latched during reset. If the device is powered up without a reset, the latch initializes to a random value and holds that value until reset is activated. The latched value of EA must agree with the current logic level at that pin in order for the device to function properly.Programming the FlashThe AT89C52 is normally shipped with the on-chip Flash memory array in the erased state (that is, contents = FFH) and ready to be programmed. The programming interface accepts either a high-voltage (12-volt) or a low-voltage (VCC) program enable signal. The low voltage programming mode provides a convenient way to program the AT89C52 ins ide the user’s system, while the high-voltage programming mode is compatible with conventional thirdparty Flash or EPROM programmers. The AT89C52 is shipped with either the high-voltage or low-voltage programming mode enabled. The respective top-side marking and device signature codes are listed in the following table. The AT89C52 code memory array is programmed byte-bybyte in either programming mode. To program any nonblank byte in the on-chip Flash Memory, the entire memory must be erased using the Chip Erase Mode.AT89C52数据手册AT89C51主要性能指数：1.与MCS-51产品指令和引脚完全相同2.8K字节可重擦写Flash闪速存储器3.1000次擦写周期4.全静态操作：0Hz-24Hz5.三级加密程序存储器6.256×8字节内部RAM7.32个可编程I/O口线8.3个16位定时器/计数器9.8个中断源10.可编程串行UART通道11.低功耗空闲和掉电模式功能特性概述：AT89C52提供以下标准功能：8K字节Flash闪速存储器，256字节内部RAM，32个I/O口线，3个16位定时/计数器，一个6向量两级中断结构，一个全双工串行通信口，片内振荡器及时钟电路。

51单片机AT89C52中文资料--------------------------------------------------------------------------------51单片机AT89C52中文资料AT89C52 ATMEL公司生产的低电压，高性能CMOS 8位单片机．片含8K byTES的可反复擦写的只读程序存储器（PEROM）和256 byTES 。

的随机存取数据存储器（RAM），器件采用ATMEL公司的高密度、非易失性存储技术生产，与标准MCS-51指令系统及8052 产品引脚兼容，片置通用8位中央处理器（CPU ）和FLASH由存储单元，功能强大AT89C52单片适用于许多较为复杂控制应用场合。

主要性能参数：与Mcs-51产品指令和引脚完全兼容。

8字节可重擦写FLASH闪速存储器1000 次擦写周期全静态操作：0HZ-24MHZ三级加密程序存储器256X8字节部RAM32个可编程I/0口线3个16 位定时／计数器8个中断源可编程串行UART通道低功耗空闲和掉电模式部结构图AT89C52部框图功能特性：AT89C52 提供以下标准功能：8字节FLASH闪速存储器，256字竹部RAM , 32个I/O口线，3个16 位定时／计数器，一个6向量两级中断结构，一个全双工串行通信口，片振荡器及时钟电路。

同时，AT89c52可降至OHz的静态逻辑操作，并支持两种软件可选的节电上作模式。

空闲方式停止CPU 的工作，但允许RAM，定时／计数器．串行通信口及中断系统继续工作。

掉电方式保存RAM 中的容，但振荡器停止工作并禁止其它所有部件工作直到下一个硬件复位.功能引脚说明：Vcc:电源电压GND:地P0：P0口是一组8位漏极开路型双向1/O 口，也即地址/数据总线复用口。

作为输出口用时．每位能吸收电流的方式驱动8个TTL 逻辑门电路，对端口P0 写“1”时，可作为高阻抗输入端用。