基于51单片机信号发生器的设计—外文翻译大学论文.doc

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1、西安交通大学城市学院本科生毕业设计（外文翻译） 本 科 毕 业 设 计 论 文 题 目 The SCM and Vision2 所在系 电气与信息工程系 学生姓名 冉乾乾 专 业 电子信息工程 班 级 电信002 学号 10010085 指导教师 金印彬 2014 年 5 月 The SCM and Vision2一、 Principle of MCUSingle-chip is an integrated on a single chip a complete computer system. Even though most of his features in a small chip,

2、 but it has a need to complete the majority of computer components: CPU, memory, internal and external bus system, most will have the Core. At the same time, such as integrated communication interfaces, timers, real-time clock and other peripheral equipment. And now the most powerful single-chip mic

3、rocomputer system can even voice, image, networking, input and output complex system integration on a single chip. Also known as single-chip MCU (Microcontroller), because it was first used in the field of industrial control. Only by the single-chip CPU chip developed from the dedicated processor. T

4、he design concept is the first by a large number of peripherals and CPU in a single chip, the computer system so that smaller, more easily integrated into the complex and demanding on the volume control devices. INTEL the Z80 is one of the first design in accordance with the idea of the processor, F

5、rom then on, the MCU and the development of a dedicated processor parted ways. Early single-chip 8-bit or all of the four. One of the most successful is INTELs 8031, because the performance of a simple and reliable access to a lot of good praise. Since then in 8031 to develop a single-chip microcomp

6、uter system MCS51 series. Based on single-chip microcomputer system of the system is still widely used until now. As the field of industrial control requirements increase in the beginning of a 16-bit single-chip, but not ideal because the price has not been very widely used. After the 90s with the b

7、ig consumer electronics product development, single-chip technology is a huge improvement. INTEL i960 Series with subsequent ARM in particular, a broad range of applications, quickly replaced by 32-bit single-chip 16-bit single-chip high-end status, and enter the mainstream market. Traditional 8-bit

8、 single-chip performance has been the rapid increase in processing power compared to the 80s to raise a few hundred times. At present, the high-end 32-bit single-chip frequency over 300MHz, the performance of the mid-90s close on the heels of a special processor, while the ordinary price of the mode

9、l dropped to one U.S. dollars, the most high-end models, only 10 U.S. dollars. Contemporary single-chip microcomputer system is no longer only the bare-metal environment in the development and use of a large number of dedicated embedded operating system is widely used in the full range of single-chi

10、p microcomputer. In PDAs and cell phones as the core processing of high-end single-chip or even a dedicated direct access to Windows and Linux operating systems. More than a dedicated single-chip processor suitable for embedded systems, so it was up to the application. In fact the number of single-c

11、hip is the worlds largest computer. Modern human life used in almost every piece of electronic and mechanical products will have a single-chip integration. Phone, telephone, calculator, home appliances, electronic toys, handheld computers and computer accessories such as a mouse in the Department ar

12、e equipped with 1-2 single chip. And personal computers also have a large number of single-chip microcomputer in the workplace. Vehicles equipped with more than 40 Department of the general single-chip, complex industrial control systems and even single-chip may have hundreds of work at the same tim

13、e! SCM is not only far exceeds the number of PC and other integrated computing, even more than the number of human beings.Hardwave introductionThe 8051 family of micro controllers is based on an architecture which is highly optimized for embedded control systems. It is used in a wide variety of appl

14、ications from military equipment to automobiles to the keyboard on your PC. Second only to the Motorola 68HC11 in eight bit processors sales, the 8051 family of microcontrollers is available in a wide array of variations from manufacturers such as Intel, Philips, and Siemens. These manufacturers hav

15、e added numerous features and peripherals to the 8051 such as I2C interfaces, analog to digital converters, watchdog timers, and pulse width modulated outputs. Variations of the 8051 with clock speeds up to 40MHz and voltage requirements down to 1.5 volts are available. This wide range of parts base

16、d on one core makes the 8051 family an excellent choice as the base architecture for a companys entire line of products since it can perform many functions and developers will only have to learn this one platform. The basic architecture consists of the following features: an eight bit ALU 32 descret

17、e I/O pins (4 groups of 8) which can be individually accessed two 16 bit timer/counters full duplex UART 6 interrupt sources with 2 priority levels 128 bytes of on board RAM separate 64K byte address spaces for DATA and CODE memoryOne 8051 processor cycle consists of twelve oscillator periods. Each

18、of the twelve oscillator periods is used for a special function by the 8051 core such as op code fetches and samples of the interrupt daisy chain for pending interrupts. The time required for any 8051 instruction can be computed by dividing the clock frequency by 12, inverting that result and multip

19、lying it by the number of processor cycles required by the instruction in question. Therefore, if you have a system which is using an 11.059MHz clock, you can compute the number of instructions per second by dividing this value by 12. This gives an instruction frequency of 921583 instructions per se

20、cond. Inverting this will provide the amount of time taken by each instruction cycle (1.085 microseconds).二、 The Introduction of AT89C511 DescriptionThe AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K bytes of Flash programmable and erasable read only memory (PEROM). The de

21、vice is manufactured using Atmels high-density nonvolatile memory technology and is compatible with the industry-standard MCS-51 instruction set. 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-bi

22、t 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.2 Function characteristicThe AT89C51 provides the following standard features: 4K bytes of Flash, 128 bytes of RAM,

23、32 I/O lines, two 16-bit timer/counters, one 5 vector two-level interrupt architecture, a full duplex serial port, one-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 mo

24、des. 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 DescriptionVCC：Supply voltage.

25、GND：Ground.Port 0Port 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 high-impedance inputs. Port 0 may also be configured to be the multiplexed address/data bus during accesses to ex

26、ternal program and data memory. In this mode P0 has internal Pull-up resistor. Port 0 also receives the code bytes during Flash programming, and outputs the code bytes during Program verification. External Pull-up resistors are required during Program verification.Port 1Port 1 is an 8-bit bi-directi

27、onal I/O port with internal Pull-up resistors. 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 Pull-up resistors and can be used as inputs. As inputs, Port 1 pins that are externally being pulled low will source curre

28、nt (IIL) because of the internal Pull-up resistors. Port 1 also receives the low-order address bytes during Flash programming and verification.Port 2Port 2 is an 8-bit bi-directional I/O port with internal Pull-up resistor. The Port 2 output buffers can sink/source four TTL inputs. When 1s are writt

29、en to Port 2 pins they are pulled high by the internal Pull-up resistor and can be used as inputs. As inputs, Port 2 pins that are externally being pulled low will source current, because of the internal Pull-up resistor. Port 2 emits the high-order address byte during fetches from external program

30、memory and during accesses to external data memory that use 16-bit addresses. In this application, it uses strong internal Pull-up resistor 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 r

31、eceives the high-order address bits and some control signals during Flash programming and verification.Port 3Port 3 is an 8-bit bi-directional I/O port with internal Pull-up resistor. The Port 3 output buffers can sink/source four TTL inputs. When 1s are written to Port 3 pins they are pulled high b

32、y the internal Pull-up resistor and can be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source current (IIL) because of the Pull-up resistor. Port 3 also serves the functions of various special features of the AT89C51 as listed below:Port 3 also receives some cont

33、rol 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 output pulse for latching the low byte of the address during accesses to external memory. This pin is also the p

34、rogram 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

35、 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 i

36、s 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/VPPExternal Access Enable. EA must be strapped to GND

37、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

38、programming enable voltage (VPP) during Flash programming, for parts that require12-volt VPP.XTAL1Input to the inverting oscillator amplifier and input to the internal clock operating circuit.XTAL2Output from the inverting oscillator amplifier.3 Oscillator CharacteristicsXTAL1 and XTAL2 are the inpu

39、t 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

40、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 Conf

41、iguration Figure2. External Clock Drive4 Idle ModeIn 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 special functions registers remain unchanged during this mode. The idle mode can b

42、e 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 execution, from where it left off, up to two machine cycles before the internal reset algorithm takes control. On-chip hardware inhi

43、bits 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

44、memory.5 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 Registers retain their values until the power-down mode is terminated. The only exit from power-down is a hard

45、ware 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.6 Program Memory Lock BitsOn the chip are three lock b

46、its which can be left unprogrammed (U) or can be programmed (P) to obtain the additional features listed in the table below.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

47、 value, and holds that value until reset is activated. It is necessary that the latched value of EA be in agreement with the current logic level at that pin in order for the device to function properly.三、 Getting Started with Vision2The Keil Software 8051 development tools listed below are programs

48、you use to compile your C code, assemble your assembly source files, link and locate object modules and libraries, create HEX files, and debug your target program.Vision2 for Windows is an Integrated Development Environment that combines project management, source code editing, and program debugging in one single, powerful environment.The C51 ANSI Optimizing C Cross Compiler creates relocatable object modules from your C source code.The A51 Macro Assembler creates relocatable object modules from your 8051 assembly source code.The BL51 Linker/Locator combines relocatable object modules