基于单片机的温湿度控制系统英文文献.doc

基于单片机的温湿度控制系统英文文献52020年4月19日文档仅供参考英文文献翻译学 生 姓名刘学毅专 业自动化学 号0833141分 院电子工程分院 6 月1. 外文原文A: Fundamentals of Single-chip Microcomputer The single-chip microcomputer is the culmination of both the development of the digital computer and the integrated circuit arguably the tow most significant inventions of the 20th century These tow types of architecture are found in single-chip microcomputer. Some employ the split program/data memory of the Harvard architecture, others follow the philosophy, widely adapted for general-purpose computers and microprocessors, of making no logical distinction between program and data memory as in the Princeton architecture, shown in Fig.3-5A-2.In general terms a single-chip microcomputer is characterized by the incorporation of all the units of a computer into a single device.Read only memory (ROM) ROM is usually for the permanent, non-volatile storage of an applications program .Many microcomputers and microcontrollers are intended for high-volume applications and hence the economical manufacture of the devices requires that the contents of the program memory be committed permanently during the manufacture of chips . Clearly, this implies a rigorous approach to ROM code development since changes cannot be made after manufacture .This development process may involve emulation using a sophisticated development system with a hardware emulation capability as well as the use of powerful software tools.Some manufacturers provide additional ROM options by including in their range devices with (or intended for use with) user programmable memory. The simplest of these is usually device which can operate in a microprocessor mode by using some of the input/output lines as an address and data bus for accessing external memory. This type of device can behave functionally as the single chip microcomputer from which it is derived albeit with restricted I/O and a modified external circuit. The use of these ROM less devices is common even in production circuits where the volume does not justify the development costs of custom on-chip ROM2;there can still be a significant saving in I/O and other chips compared to a conventional microprocessor based circuit. More exact replacement for ROM devices can be obtained in the form of variants with piggy-back EPROM(Erasable programmable ROM )sockets or devices with EPROM instead of ROM 。These devices are naturally more expensive than equivalent ROM device, but do provide complete circuit equivalents. EPROM based devices are also extremely attractive for low-volume applications where they provide the advantages of a single-chip device, in terms of on-chip I/O, etc. ,with the convenience of flexible user programmability.Random access memory (RAM). RAM is for the storage of working variables and data used during program execution. The size of this memory varies with device type but it has the same characteristic width (4,8,16 bits etc.) as the processor ,Special function registers, such as stack pointer or timer register are often logically incorporated into the RAM area. It is also common in Hard type microcomputers to treat the RAM area as a collection of register; it is unnecessary to make distinction between RAM and processor register as is done in the case of a microprocessor system since RAM and registers are not usually physically separated in a microcomputer .Central processing unit (CPU). The CPU is much like that of any microprocessor. Many applications of microcomputers and microcontrollers involve the handling of binary-coded decimal (BCD) data (for numerical displays, for example) ,hence it is common to find that the CPU is well adapted to handling this type of data .It is also common to find good facilities for testing, setting and resetting individual bits of memory or I/O since many controller applications involve the turning on and off of single output lines or the reading the single line. These lines are readily interfaced to two-state devices such as switches, thermostats, solid-state relays, valves, motor, etc.Parallel input/output. Parallel input and output schemes vary somewhat in different microcomputer; in most a mechanism is provided to at least allow some flexibility of choosing which pins are outputs and which are inputs. This may apply to all or some of the ports. Some I/O lines are suitable for direct interfacing to, for example, fluorescent displays, or can provide sufficient current to make interfacing other components straightforward. Some devices allow an I/O port to be configured as a system bus to allow off-chip memory and I/O expansion. This facility is potentially useful as a product range develops, since successive enhancements may become too big for on-chip memory and it is undesirable not to build on the existing software base.Serial input/output . Serial communication with terminal devices is common means of providing a link using a small number of lines. This sort of communication can also be exploited for interfacing special function chips or linking several microcomputers together .Both the common asynchronous synchronous communication schemes require protocols that provide framing (start and stop) information .This can be implemented as a hardware facility or U(S) ART(Universal(synchronous) asynchronous receiver/transmitter) relieving the processor (and the applications programmer) of this low-level, time-consuming, detail. t is merely necessary to selected a baud-rate and possibly other options (number of stop bits, parity, etc.) and load (or read from) the serial transmitter (or receiver) buffer. Serialization of the data in the appropriate format is then handled by the hardware circuit.Timing/counter facilities. Many application of single-chip microcomputers require accurate evaluation of elapsed real time .This can be determined by careful assessment of the execution time of each branch in a program but this rapidly becomes inefficient for all but simplest programs .The preferred approach is to use timer circuit that can independently count precise time increments and generate an interrupt after a preset time has elapsed .This type of timer is usually arranged to be reloadable with the required count .The timer then decrements this value producing an interrupt or setting a flag ，when the counter reaches zero. Better timers then have the ability to automatically reload the initial count value. This relieves the programmer of the responsibility of reloading the counter and assessing elapsed time before the timer restarted ,which otherwise wound be necessary if continuous precisely timed interrupts were required (as in a clock ,for example).Sometimes associated with timer is an event counter. With this facility there is usually a special input pin , that can drive the counter directly. Timing components. The clock circuitry of most microcomputers requires only simple timing components. If maximum performance is required, a crystal must be used to ensure the maximum clock frequency is approached but not exceeded. Many clock circuits also work with a resistor and capacitor as low-cost timing components or can be driven from an external source. This latter arrangement is useful is external synchronization of the microcomputer is required. 2. 外文资料翻译译文单片机基础单片机是电脑和集成电路发展的巅峰，有据可查的是她们也是20世纪最有意义的两大创造。这两种特性在单片机中得到了充分的体现。一些厂家用这两种特性区分程序内存和数据内存在硬件中的特性，依据同样的原理广泛的适用于一般目的的电脑和微电脑，一些厂家在程序内存和数据内存之间不区分的像Princeton特性。只读存贮器(ROM) ROM是一般的永久性的，非应用程序的易失性存储器。不少微机和单片机用于大批量应用，因此，经济的设备制造要求的程序存储器的内容是在制造期间永久性的刻录在芯片中，这意味着严谨的方法，因为修改ROM代码不能制造之后发展。这一发展过程可能涉及仿真,使用硬件仿真功能以及强大的软件工具使用先进的开发系统。一些制造商在其提供的设备包括的范围（或拟使用）用户可编程内存.其中最简单的一般是设备能够运行于微处理器模式经过使用一些输入/输出作为地址线额外的ROM选项和数据总线访问外部内存.这种类型的设备能够表现为单芯片微型计算机尽管有限制的I / O和外部修改这些设备的电路.小内存装置的应用是非常普遍的在永久性内存的制造中 2;但依然能够在我节省大量成本I/ O和其它芯片相比，传统的基于微处理器电路.更准确的ROM设备更换，可在与形式变种背驮式EPROM（可擦除可编程只读存储器）插座或存储器，而不是ROM器件。这些器件自然价格比同等ROM设备贵，但不提供完整的等效电路.EPROM的设备也非常有吸引力对于低容量应用中，她们提供的单芯片器件的优势，在以下方面的板载I / O等，在灵活的用户可编程带来的便利。随机存取存储器（RAM）RAM用于变量和工作在程序使用该存储器的执行.随数据存储设备的大小不同类型而有所不同，但具有相同的特征宽度（4,8,16 比特等）作为处理器。特殊功能寄存器，如栈指针或定时器寄存器，往往逻辑纳入内存区域.它也在型微电脑的硬件中做集中内存，它是不必要的区分内存和处理器之间的区别在一般不物理上分开的微机中。中央处理单元（CPU）CPU是很象微型电子计算机和微控制器的任何微电脑.许多微电脑和微控制器涉及到二进制编码(十进制处理（BCD）的数据为例）数字显示，因而，常常能够发现该CPU是很适合处理这种类型的数据。对设施良好与否进行的测试，设置和重置单个位的内存或I / O控制器的应用程序，也是常见的因为许多涉及打开和关闭的单输出线或在单线.这些线很容易连接到二进制的设备，如开关，恒温器，固态继电器，阀门，电机等并行输入/ 输出并行输入和输出的计划有所不同，在不同的微机，在大多数设立一个机制，至少选择让其中一些引脚输出，一些引脚输如是非常灵活的。这可能适用于所有或端口.有些I / O线直接连接到适当的设备，例如，荧光显示器，也能够提供足够的电流，使接口和其它设备直接相连.一些设备允许一个I / O端口,其它组件将作为系统总线配置为允许片外存储器和I / O扩展。这个设施是潜在有用的一个产品系列的发展，因为连续增强可能成为太上存储器，这是不可取的，不是建立在现有的软件基础上的。串行输入/输出串行通信是指与终端设备的链接使用少量的通讯线.这种通讯也可利用特殊的接口连接功能芯片使几个微型机连在一起。双方共同异步同步通信方案要求的规则提供成帧（启动和停止）的信息。这能够作为一个硬件设施或U（拧）艺术（通用执行（同步）异步接收器/发送器）减轻处理器（和应用程序）的这种低层次的确费时.它也只需要选择一个波特率及其它可能的选择（停止位，奇偶校验等）和负载号码（或读取），串行发送器（或接收）的缓冲器.进行适当的格式的数据串行处理，然后由硬件电路完成。定时/计数器设施许多应用的单片机需要对过去的真实时间准确的评价。这能够由每个程序中的执行时间分支认真评估，但除最简单的程序外，她的工作效率不高。首选方法是使用计时器电路，能独立计算精确的时间增量，并生成一个预设的时间后中断的时间。这种类型的定时器一般在所要求的数量可重载中应用。计时器然后减少此值产生中断或设置标记时，计数器到达零.更好的计时器有自动加载初始值的功能。这将缓解重新加载计数器和评估所用的时间，计时器重新启动之前这是必要的。有时候与定时器相关的是一个事件计数器。这个设备一般有一个特殊的输入引脚，可直接驱动计数器。定时元件大多数微型计算机时钟电路只需要简单的计时元件.如果要求最高性能，必须使用晶体以确保最大时钟频率接近，但不会超出。许多时钟电路，还具有电阻和低电容工作成本定时元件，也能够从外部源驱动。这后一种安排是有用的在微机外部同步是必须的时候。