步进电机及单片机英文文献及翻译

步进电机及单片机英文文献及翻译 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 外文文献: Knowledge of the stepper motor What is a stepper motor: Stepper motor is a kind of electrical pulses into angular displacement of the implementing agency. Popular little lesson: When the driver receives a step pulse signal, it will drive a stepper motor to set the direction of rotation at a fixed angle (and the step angle). You can control the number of pulses to control the angular displacement, so as to achieve accurate positioning purposes; the same time you can control the pulse frequency to control the motor rotation speed and acceleration, to achieve speed control purposes. What kinds of stepper motor sub-: In three stepper motors: permanent magnet (PM), reactive (VR) and hybrid (HB) permanent magnet stepper usually two-phase, torque, and smaller, step angle of 7.5 degrees or the general 15 degrees; reaction step is generally three-phase, can achieve high torque output, step angle of 1.5 degrees is generally, but the noise and vibration are large. 80 countries in Europe and America have been eliminated; hybrid stepper is a mix of permanent magnet and reactive advantages. It consists of two phases and the five-phase: two-phase step angle of 1.8 degrees while the general five-phase step angle of 0.72 degrees generally. The most widely used Stepper Motor. What is to keep the torque (HOLDING TORQUE) How much precision stepper motor? Whether the cumulative: The general accuracy of the stepper motor step angle of 3-5%, and not cumulative. Stepper motor to allow the minimum amount of surface temperature Stepper motor to allow the minimum amount of surface temperature: Stepper motor causes the motor temperature is too high the first magnetic demagnetization, resulting in loss of torque down even further, so the motor surface temperature should be the maximum allowed depending on the motor demagnetization of magnetic material points; Generally speaking, the magnetic demagnetization points are above 130 degrees Celsius, and some even as high as 200 degrees Celsius, so the stepper motor surface temperature of 80-90 degrees Celsius is normal. - 1 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 How to determine the stepper motor driver DC power supply: A. Determination of the voltage Hybrid stepping motor driver power supply voltage is generally a wide range (such as the IM483 supply voltage of 12 ~ 48VDC), the supply voltage is usually based on the work of the motor speed and response to the request to choose. If the motor operating speed higher or faster response to the request, then the voltage value is high, but note that the ripple voltage can not exceed the maximum input voltage of the drive, or it may damage the drive. B. Determination of Current Power supply current is generally based on the output phase current drive I to determine. If a linear power supply, power supply current is generally preferable 1.1 to 1.3 times the I; if we adopt the switching power supply, power supply current is generally preferable to I, 1.5 to 2.0 times. The main characteristics of stepping motor: A stepper motor drive can be added operate pulse drive signal must be no pulse when the stepper motor at rest, such as If adding the appropriate pulse signal, it will to a certain angle (called the step angle) rotation. Rotation speed and pulse frequency is proportional to. 2 Dragon step angle stepper motor version is 7.5 degrees, 360 degrees around, takes 48 pulses to complete. 3 stepper motor has instant start and rapid cessation of superior characteristics. Change the pulse of the order of 4, you can easily change the direction of rotation. Therefore, the current printers, plotters, robotics, and so devices are the core of the stepper motor as the driving force. Stepper motor control example We use four-phase unipolar stepper motor as an example. The structure shown in Figure 1: Four four-phase winding leads (as opposed to phase A1 A2 B1 phase phase B2) and two public lines (to the power of positive). The windings of one phase to the power of the ground. So that the windings will be inspired. We use four-phase eight-beat control, ie, 1 phase 2 phase alternating turn, would enhance resolution. 0.9 ? per step can be transferred to control the motor - 2 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 excitation is transferred in order as follows: If the requirements of motor reversal, the transmission excitation signal can be reversed. 2 control scheme Control system block diagram is as follows The program uses AT89S51 as the main control device. It is compatible with the AT89C51, but also increased the SPI interface and the watchdog module, which not only makes the debugging process becomes easy and also more stable. The microcontroller in the program mainly for field signal acquisition and operation of the stepper motor to calculate the direction and speed information. Then sent to the CPLD. CPLD with EPM7128SLC84-15, EPM7128 programmable logic device of large-scale, for the ALTERA company's MAX7000 family. High impedance, electrically erasable and other characteristics, can be used for the 2500 unit, the working voltage of +5 V. CPLD receives information sent from the microcontroller after converted to the corresponding control signal output to the stepper motor drive. Put the control signal drives the motor windings after the input, to achieve effective control of the motor. 2.1 The hardware structure of the motor drive Motor drive using the following circuit: R1-R8 in which the resistance value of 320Ω. R9-R12 resistance value 2.2KΩ. Q1-Q4 as Darlington D401A, Q5-Q8 for the S8550. J1, J2 and the stepper motor connected to the six-lead。 Advantages and disadvantages of stepper motor Advantages 1. The motor rotation angle is proportional to the number of pulses; 2. When the motor stopped with a maximum torque (when the winding excitation time); 3. Since the accuracy of each step in the three per cent to five per cent, and the error will not accumulate to the next step and thus has better positional accuracy and repeatability of movement; 4. Excellent response from the stop and reverse; 5. In the absence of brush, high reliability, it just depends on the life of the motor bearing life; 6. Motor response only determined by the number of input pulses, which can be used open loop control, which makes the motor and control structure can be relatively simple System cost - 3 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 7. Just load directly connected to the motor shaft can also be extremely slow synchronous rotation. 8. Speed is proportional to the pulse frequency, and thus a relatively wide speed range. Shortcomings 1. If not properly controlled prone to resonance; 2. Difficult operation to a higher speed. 3. Difficult to obtain high torque 4. There is no advantage in terms of volume weight, low energy efficiency. 5. Over load will destroy the synchronization, the work will be issued when high-speed vibration and noise. Stepper motor drive requirements (1) to provide fast rise and fall of current speed, the current waveform as close as possible rectangle. For the period ended with the release of the loop current flow, to reduce the winding ends of the back electromotive force, to accelerate the current decay. (2) rhyme with higher power and efficiency. Stepper motor driver, which is the control pulse signal emitted into the angular displacement of the stepper motor, or: the control system sends a pulse signal each through the stepper motor drive to rotate a step angle. That is the stepper motor speed is proportional to the frequency and pulse signals. Therefore, the frequency control pulse signal, to be precise motor speed control; control the number of step pulses to connect the motor accurately. Stepper motor drive there are many, we should take a reasonable choice of power requirements of the drive, the following were introduced various types of typical drive. The latest technological developments Domestic and international research on the sub-drive technology is very active, high-performance sub-driver circuit can be broken down into thousands or even any subdivision. Now able to do complicated calculations to make after the breakdown of uniform step angle, which greatly improves the resolution of stepper motor pulses, reduce or eliminate the vibration, noise and torque ripple, the stepper motor is more "class server" feature. - 4 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 The actual role of step angle: in the absence of sub-drive, the user select a different number of phases depends mainly on the stepper motor to meet their own requirements on the step angle，If you use the sub-drive, the user can change the drive number of segments, can dramatically change the actual step angle stepper motor 'phases' of change in the role of the actual step angle is almost negligible. Introduction of AT89C51 Description The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K 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 MCS-51 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 AT89C51 is a powerful microcomputer which provides a highly-flexible and cost-effective solution to many embedded control applications. Function characteristic The AT89C51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM, 32 I/O lines, two 16-bit timer/counters, a five vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator and clock circuitry. In addition, the AT89C51 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 Description VCC:Supply voltage. GND:Ground. Port 0: Port 0 is an 8-bit open-drain bi-directional 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 - 5 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 inputs.Port 0 may 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 programverification. External pullups are required during programverification. Port 1 Port 1 is an 8-bit bi-directional 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.Port 1 also receives the low-order address bytes during Flash programming and verification. Port 2 Port 2 is an 8-bit bi-directional 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, 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, it uses strong internal pullupswhen 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 3 Port 3 is an 8-bit bi-directional 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 listed below: - 6 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 Port 3 also receives some control signals for Flash programming and verification. RST Reset input. A high on this pin for two machine cycles while the oscillator is running resets the device. ALE/PROG Address Latch Enable output pulse for latching the low byte of the address during accesses to external memory. This pin is also the program pulse input (PROG) during Flash programming.In normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and may be used for external timing or 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. PSEN Program Store Enable is the read strobe to external program memory.When the AT89C51 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. EA/VPP External Access Enable. EA must be strapped to GND in order to enable the device to fetch - 7 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 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, for parts that require12-volt VPP. 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 maximum voltage high and low time specifications must be observed. Figure 1. Oscillator Connections Figure 2. External Clock Drive Configuration Idle Mode In 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 - 8 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 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 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 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. Power-down Mode In 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 Registers retain 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. - 9 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 中文译文: 步进电机的知识 什么是步进电机: 步进电机是一种把电脉冲转化为角位移的执行机构。通俗的说:当驱动程序收到一个步进脉冲信号，将驱动步进电机轴旋转一个固定的角度(步进角)。您可以通过控制脉冲个数来控制角位移，从而达到准确定位的目的;同时，你可以通过控制脉冲频率来控制电机的旋转速度和加速度，实现速度控制的目的。 步进电机的种类: 步进电机分为三种:永磁式(PM)，反应式(VR)和混合式(HR)永磁式步进电机一般为两相，转矩和体积较小，步进角一步7.5度或15度;反应式一般有三相可以实现大转矩输出，步进角一般是1.5度，但噪声和振动大。在欧洲和美洲80个国家已被淘汰;混合式步进是混合了永磁式和反应的优势。它由两相和五相:一般两相的步距角是1.8度，而的五相步距角为0.72度。是使用最广泛的的步进电机。 步进电机允许的最高表面温度 步进电机温度过高首先会的磁性 材料 关于××同志的政审材料调查表环保先进个人材料国家普通话测试材料农民专业合作社注销四查四问剖析材料 退磁，导致转矩降低甚至失步，电机表面温度允许的最大值取决于的磁性材料退磁点;一般来说，磁性材料退磁点在摄氏130度以上有些材料甚至高达摄氏200度高，所以步进电机表面温度在摄氏80-90度是正常的。 步进电机精度为多少,是否累积 一般步进电机的精度为步进角的3-5%，且不累积 如何确定步进电机驱动器直流电源 A.电压确定 混合式步进电机驱动器的电源电压范围较广(比如IM483的供电电压12?48VDC)，电源电压通常根据电机的转速和响应要求来选择。如果要求较快的运行速度较高的响应速度就选用较高的电压，但注意电源电压的峰值不能超过驱动器的最大输入电压，否则可能会损坏驱动器。 B.电流确定 电源电流一般根据输出相电流I来确定。如果采用线性电源，电源电流一般可取I的1.1?1.3倍;如果采用开关电源，电源电流一般可取I的1.5?2.0倍。 步进电机的主要特性 在步进电机关机时要确保没有脉冲信号，当电机运行时 如果加入适当的脉冲信号，它会转过一定的角度(称为步距角是)。转速与脉冲频率成正比。 2龙式步进电机步距角7.5度，旋转360度，需要48个脉冲来完成。 3步进电机具有快速启动和停止的优良特性。 4只要改变脉冲，可以很容易地改变电机轴旋转的方向。 因此，目前的打印机，绘图仪，机器人设备以步进电机作为动力核心。 步进电机控制的例子 我们以四相单极步进电机为例: - 10 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 四个相绕组引出四个相和两个公共线(连接到正极)。一相接地。会被激发，。我们使用四相八拍控制，即第1阶段第2阶段交替反过来，会提高分辨率。步距角0.9?，可以转移到控制电机励磁是为了转移如下: 如果电机反转的要求，传输的激励信号可以逆转的。 2控制 方案 气瓶 现场处置方案 .pdf气瓶 现场处置方案 .doc见习基地管理方案.doc关于群访事件的化解方案建筑工地扬尘治理专项方案下载 控制系统框图如下 该方案采用AT89S51的主要控制装置。它是与AT89C51兼容，但也增加了SPI接口和看门狗模块，这不仅使调试变得更容易，也更稳定。单片机程序主要用于现场信号的采集和通过步进电机的运转来计算的方向和速度信息。然后将信息发送到CPLD。 CPLD使用EPM7128SLC84-15，ALTERA公司的MAX7000系列可编程逻辑器件EPM7128。具有高阻抗，电可擦除等特点，可用单位数为2500单位，工作电压+5 V CPLD接收脉冲后转换为相应的控制信号输出到步进电机驱动器，从微控制器发送的信息。输入后把控制信号发送到驱动电机绕组，以达到有效控制电机的目的。 2.1为电机驱动器的硬件结构 电机驱动器通过下面的电路来实现: R1?R8的电阻值为320Ω。 R9-R12的电阻值为2.2KΩ。 Q1?Q4作为达林顿401A，Q5-Q8为S8550。 J1，J2和步进电机连接到六个接口。 步进电机优点和缺点 优势 1。电机的旋转角度与脉冲数成正比; 2。当电机停转为最大转矩(当绕组励磁时); 3。由于每一步准确度为百分之三到五，而且误差不会累积到下一步，因而具有更好定位精度和重复定位精度; 4。优良的启动和制动特性_; 5。没有电刷，可靠性高，电机的寿命只是取决于电机轴承; 6。电机_仅由输入脉冲数决定，可用于开环控制，这使得电机和控制结构确定相对简单 系统成本 7。只是负载直接连接到电机轴也可以极其缓慢旋转 8。速度与的脉冲频率成正比，因此，有相对较宽的调速范围 缺点 1。如果没有适当的控制，容易共振; 2。高速操作难度较大 3。难以获得大转矩 4。没有体积小，重量轻，能耗低，效率高等方面优势 5。过载时会破坏同步性，工作时会发出时较大的振动和噪音 步进电机驱动要求 (1)为了满足速度迅速上升或下降的要求，波形应当尽可能接近矩形 以释放回路电流流，绕组两端的反电动势，加速电流衰减 (2)具有较高功率和效率 步进电机驱动器，把输入的脉冲信号转化为角位移，每当控制系统发出一个脉冲信号，步进电机驱动就旋转一个步距角，步进电机的速度与的脉冲信号频率成正比， - 11 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 因此，通过控制脉冲信号频率，就可以精确控制电机转速步进脉冲数决定准确连接为电机步进电机驱动器有很多，我们应该根据功率采取的合理的方式选择驱动器 最新的技术发展 国内和国际上对于驱动技术的研究十分活跃，高性能子驱动电路可以细分成几千部分甚至任意细分，现在已经能够做到通过复杂的计算统一步距角，大大提高了步进电机的脉冲分辨率，减少或消除振动，噪声和转矩波动，步进电机有了更多“类伺服”功能 实际作用:步距角细分驱动器出现之前，用户需要选择不同的相来获取不同的步进电机步距角，以满足自己的要求，如果使用细分驱动器，用户可以通过更改驱动器号段，来改变实际的步距角，相数对实际步距角的作用几乎可以忽略不计 AT89C51的介绍 描述 AT89C51是一个拥有4K字节FLASH编程功能和可擦除只读储存器的低功耗，高性能CMOS8位微机(PEROM)。该设备是采用Atmel的高密度非易失性内存技术并与工业标准的的MCS-51指令集和引脚兼容。芯片上的Flash允许程序存储器通过系统或由传统的非易失性存储器编程重新编程。通过把一个多功能8位CPU与一个单一的芯片上的Flash相结合的，Atmel的AT89C51是一个功能强大微型计算机为许多嵌入式控制程序提供了高度灵活和成本效益的解决方案。 功能特点 AT89C51具有以下功能:4K字节的Flash，128字节RAM，32 I / O口，两个16位定时器/计数器，一个五向量2级中断机构，一个全双工串行口，芯片振荡器和时钟电路。此外，AT89C51支持频率为0的静态逻辑运算，并支持两种节电模式。空闲模式时CPU停止工作，同时允许RAM，定时器/计数器，串口和中断系统继续运作。掉电模式保存RAM的内容，但冻结振荡器，禁用所有其他芯片功能，直到硬件复位。 引脚描述 VCC:电源电压 GND:地 端口0: 端口0是一个8位漏极开路双向I / O端口。作为一个输出端口，每个引脚可以驱动8个TTL输入端。当1写入端口0引脚，引脚可作为高阻输入端.端口0也可以设定成地址/数据在访问外部程序和数据存储器时的总线。在这种模式下，口0内部上拉.电阻口0 在Flash编程期间也可以收到代码字节，输出程序改变的代码字节。程序改变期间还要外部上拉电阻 端口1 - 12 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 端口1是一个具有内部上拉电阻的8位双向I / O端口端口1输出缓冲器可以驱动四个TTL 输入.当1被写入端口1它们被内部上拉电阻上拉为高电平并可以用作输入口。作为输入口时，由于内部上拉电阻的作用，引脚被外部信号拉低时输出一个电流，flash编程和校验时端口1也会接收到低地址信号。 端口2 端口2是一个具有内部上拉电阻的8位双向I / O端口。端口2输出缓冲器可以驱动四个TTL 输入。当1S写入端口2引脚他们被内部上拉电阻拉到高电平，并可以用作输入口。作为输入口时，由于内部上拉电阻的做用，端口2引脚被外部信号拉至低电平时，将输出电流，端口2在访问使用16位地址的外部数据存储器时发出的高位地址字节。在此应用中，它采用强大的内部上拉电阻，发光1S。在访问使用8位地址的外部数据存储器时，端口2也会收到一些高八位地址信号或者控制信号。 端口3 端口3是一个具有内部上拉电阻的8位双向I / O端口。端口3输出缓冲器可以驱动四个TTL 输入。当1S被写入端口3的引脚，他们被内部上拉电阻拉到高电平，并可以用作输入口。作为输入口时，由于内部上拉电阻的做用，端口2引脚被外部信号拉至低电平时，将输出电流。端口3还为AT89C51提供各种特殊功能，如下: 端口引脚 第二功能 P3.0 RXD P3.1 TXD P3.2 INT0 P3.3 INT1 P3.4 T0 P3.5 T1 P3.6 WR P3.7 RD RST 复位输入引脚。震荡器运行时，两个运行周期的高电平将使设备复位。 ALE / PROG 在访问外部存储器时地址锁存使能输出脉冲锁存的低八位地址。该引脚也是程序在Flash 编程时的PROG。正常运行时ALE以恒定的速率发出振荡频率的1/6的脉冲信号， - 13 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 可用作外部时钟或定时。但是请注意，，在每次访问外部数据存储器都有一个ALE脉冲跳过。。 如果需要，可以通过把0 SFR置位为8EH来禁用ALE。此时，ALE仅执行MOVX或MOVC指令。如果单片机在执行外部的工作，应将ALE设置为禁用。 PSEN 程序储存允许输出是外部程序存储器的读选通信号，当AT89C51由外部程序存储器读取指令时，每个机器周期两次PSEN 有效，即输出两个脉冲。在此期间，当访问外部数据存储器时，这两次有效的PSEN 信号不出现。 EA/ VPP 外部访问允许。 EA必须绑到GND才能使设备开始在0000H到FFFFH位取代码。但是请注意，如果锁存位1被编程，EA将锁存位置上复位。若EA为高电平则单片机执行内部程序。在Flash编程时，也可以使用使用12V编程电压 VCC XTAL1:震荡器反相放大器及内部时钟发生器的输入端。 XTAL2:震荡器反相放大器的输出端。 时钟振荡器的特性 时钟振荡器是可以设置为内部振荡器的反相放大器XTAL1和XTAL2分别为其出入端和输出端，如图1所示。石英晶体或陶瓷谐振器都可以作为其材料。如图2所示要想通过外部时钟来驱动它， XTAL1工作时XTAL2应悬空。对外部时钟信号的占空比没有特殊要求，因为外部时钟信号是通过一个2分频触发器后作为内部时钟信号的，但最小高电平持续时间和最大的低电平持续时间应该符合要求。 - 14 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 内部振荡电路 外部振荡电路 闲散模式 在闲散模式下，CPU停止工作，而所有其他元件依然处于工作状态。该模式是通过软件控制的。这种模式下，片上RAM和所有特殊功能寄存器的内部数据不变。该模式可以由任何可用的终止指令或者硬件重置来终止当由硬件复位来终止闲散工作模式时，中央处理器CPU通常是从激活空闲模式那条指令的下一条开始继续执行程序的，要完成内部复位操作，硬件复位脉冲要保持两个机器周期有效，在这种情况下，内部禁止中央处理器CPU访问片内RAM，而允许访问其他端口，这是为了避免可能对端口产生的意外写入:激活空闲模式的指令后面的一条指令不应是一条对端口或外部存储器的写入指令。 掉电模式 在掉电模式下，振荡器停止运行，断电指令是最后一条要执行的指令。片上RAM和特殊功能寄存器保持原值，直到掉电模式终止。终止掉电唯一的方式是硬件复位。复位将重置SFR，但不改变RAM的内容。复位不能被激活，直到VCC恢复到其正常水平，以确保有足够长的时间使振荡器重新启动并稳定。。 ALE P0 P1 P2 P3 模式 程序存储器 PSEN 1 1 闲散模式 内部 数据 数据 数据 数据 1 1 闲散模式 内部 浮空 数据 地址 数据 0 0 掉电模式 外部 数据 数据 数据 数据 - 15 - 山 东 建 筑 大 学 毕 业 设 计 外 文 文 献 翻 译 及 译 文 0 0 掉电模式 外部 数据 数据 数据 数据 - 16 -