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1、Unit 19,Single-chip Microprocessors,Electronic and Communication Engineering English,电子与通信工程专业英语,单片机,Unit 19 Single-chip Microprocessors,Single-chip Microprocessors,单片机 单片机是数字计算机和集成电路发展中的一个顶峰，可以说这二者是20世纪两项最有意义的发明,The single-chip microcomputer is the culmination of both the development of the digital
2、 computer and the integrated circuit, arguably the two most significant inventions of the 20th century.1,Text,Fig 19-1 A Harvard type,单片机有两种体系结构。一些使用如图19-1所示的程序/数据独立存储的哈弗结构，另一些遵循通用计算机和微机广泛采用的普林斯顿结构，在程序和数据存储间不做逻辑区分，如图19-2所示。,These two types of architecture are found in single-chip microcomputers. Som
3、e employ the split program/data memory of the Harvard architecture, shown in Fig 19-1, others follow the philosophy, widely adopted for general-purpose computers and microcomputers, of making no logical distinction between program and data memory as in the Princeton architecture, shown in Fig 19-2。,
4、Text,Fig 19-2 A Conventional Princeton type,In general terms a single-chip microcomputer is characterized by the incorporation of all the units of a computer into a single device, as shown in Fig 19-3.,概括地说，单片机是将计算机所有部件合并到一个单独的芯片上，如图19-3所示。,Text,Fig 19-3 Principal features of a microcomputer,1. Read
5、 Only Memory(ROM) ROM is usually for the permanent, non-volatile storage of an application program. Many microcomputers and microcontrollers are intended for high-volume applications and hence the economical manufactures of the devices require that the content of the program memory be committed perm
6、anently during the manufacture of the 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 u
7、se of powerful software tools.,1只读存储器（ROM） ROM常用于永久、不变地存储一个应用程序。许多微机和微控制器是供海量的应用程序使用，因此，在芯片生产过程中，设备制造的经济性要求程序内容永久存储。显然，由于制造后不能改写，这就意味着ROM代码开发要求非常严格。该开发过程可能包括使用复杂的具有硬件仿真功能的开发系统和强有力的软件工具进行仿真。,Text,2. Random Access Memory (RAM) RAM is for the storage for working variables and data during program execut
8、ion. The size of this memory varies with device type but it has the same characterized width (4, 8, 16 bits, etc. )as the processor. Special function registers, such as a stack pointer or timer register are often logically incorporated into the RAM rate. It is also common in Harvard type microcomput
9、ers to treat the RAM area as a collection of registers; it is unnecessary to make a 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.,2随机存储器（RAM） RAM是用来在程序运行期间存储工作变量和数据的。RA
10、M的大小因设备类型有所不同，但有着与处理器相同的特征字长（4位、8位、16位等），像堆栈指针或定时寄存器等一些特殊功能寄存器，在逻辑上通常与RAM同级。在哈弗结构的微机中，把RAM区域看作寄存器的集合也是常见的。自从微机内的RAM和寄存器不再进行物理分隔以来，像在微处理器系统中那样对RAM和处理器的寄存器加以区分就没有什么必要了。,Text,3. Central Processing Unit(CPU) The CPU is much like that of any microprocessor. Many applications of micro-computers and microc
11、ontrollers involve the handling of binary-coded decimal(BCD)data(for numerical displays, for examples); 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
12、 since many controller applications involve the turning on and off of single output lines or the reading of a single line.,3中央处理器（CPU） 单片机中的CPU很像微处理器中的CPU。微机和微控制器的许多应用涉及BCD（二进制编码的十进制数）数据的处理（例如用于数值的显示），因此，CPU能很好地处理这类数据就很平常了。它能很好地用于测试、设置、重置内存和I/O的位，也很常见，因为许多控制器的应用程序包含着对单个输出线的开启或读取。,Text,4. Parallel In
13、put/Output Parallel input and output schemes vary somewhat in different micro- computers; in most cases 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 dire
14、ct interfacing to, for example, fluorescent displays, or can provide sufficient current to make interfacing to other components straight forward. Some devices allow an I/O port to be configured as a system bus to allow off-chip memory and I/O expansion.2 4并行输入输出 不同微机中的并行输入输出方案略有不同。在多数情况下提供了一种机制，它至少允
15、许灵活选择哪些引脚作为输出哪些引脚作为输入。这可应用到所有或部分端口。一些I/O线适于直接接入，如荧光显示；或可以提供足够的电流来直接连接其他元件。一些设备允许把I/O端口配置成系统总线以连接片外存储器和I/O扩展,Text,Text,5. Serial InputOutput Serial communication with terminal devices is a common means of providing a link using a small number of lines. This sort of communication can also be exploited
16、 for interfacing special function chips or linking several microcomputers together. Both the common asynchronous and synchronous communication schemes require protocols that provide framing (start and stop) information. 5串行输入/输出 通过使用少量的线路与终端设备连接进行串行通信是常用的手段。这种通信方式也可以开发用来连接具有特殊功能的芯片，或将若干微机连接起来。常见的同步和异步通信方案需要包含提供启停帧信息的协议。,6. Timer/Counter facilities Many applications of single-chip microcomputers require accurate evaluation of elapsed real time. This can be determined by careful assess
