1、 中文 2722 字 外文资料翻译 LED using digital tube digital display its high-brightness, indicating the advantages of intuitive intelligence is widely used in areas such as equipment and household appliances. AT89C52This article describes a single-chip microcomputer as the core, to a total of anode high-bright
2、ness LED L ED as a display composed of seven figures show that the practical design of multi-function electronic clocks, the clock shows a week, hour, minute, second, it can be switched to year, month, day showed that the whole point of music at the same time and from time to time the alarm time and
3、 other functions can also be used for electronic stopwatch. Clock circuit is the heart of the computer, which controls the rhythm of the work of the computer is through the completion of complex sequential circuits function in different directions. Clock, since it was invented that day on, peoples l
4、ives has become an indispensable tool, especially in this era of efficient, the clock is in the human production and living, learning and other fields is widely. However, with the passage of time, people not only to the requirements of the clock is getting higher and higher precision, and functional
5、 requirements for the clock more and more, the clock has not only a tool used to display time, in many practical applications It also needs to be able to achieve more other functions. Features such as alarm clock, calendar display, temperature measurement function, humidity measurements, voltage mea
6、surements, frequency measurements, have been under-voltage alarm function. Digital clocks to the peoples production and life has brought great convenience, but also greatly expands the time feature the original clocks. Such as regular auto-alarm, Automatic time-ling, time process automation, from ti
7、me to time broadcast, from closed-circuit automatic lights, oven timer switch, on-off power equipment, electrical and even a variety of timing is automatically enabled, all of which are based on digital clocks and watches based. It can be said that the design of the significance of multi-function Di
8、gital Clock Digital Clock is not just itself, a greater significance of the multi-function digital clock in a number of real-time control systems. In many practical applications, as long as the digital clock circuit of the programs and hardware to a certain degree of modification could be useful for
9、 real-time control system, which applied to the actual work and production to. Thus, digital clock and to expand its applications, has a very practical significance. With the development of human civilization, science and technology, there is the request of the clock continues to improve. Clock has
10、not only seen as a tool to display the time, in many practical applications also need to be able to achieve more other functions. High-precision, multifunction, small size, low power consumption, is the development trend of the modern clock. In this trend, digital clock, multifunction clock has beco
11、me the modern design of the production of research-led direction. This article is based on this design direction for the control of a single-chip core design requirements of a multi-function indicators in line with the digital clock. The design is based on the principle of single-chip technology to
12、chip AT89C52single-chip microcomputer as the core controller, through the production of hardware and software procedures for the preparation, design to produce a multi-functional digital clock system. The clock system mainly by clock module, alarm module, the ambient temperature detection module, li
13、quid crystal display module, control module and the keyboard signal prompted module. System is simple and clear user interface that can 4V 7V DC power under normal operation. Able to accurately display time (display format hh: mm: seconds seconds, 24-hour system), may be time to adjust at any time,
14、with clock time settings, alarm on / off, only to make functions, where the clock to measure the ambient temperature and displayed. Hardware and software design into the guiding ideology, give full play to the single-chip features, most of the functions through software programming to achieve, the c
15、ircuit is simple and clear, high system stability. At the same time, the clock system also has the power of small, low cost, and highly practical. System components as a result of less use, single-chip occupied by the I / O port not more than, the system has a certain degree of scalability. Clock de
16、sign is no theory of discrete logic, programmable logic, or using full-custom silicon devices of any digital design, in order to successfully operate and reliable clock is crucial. Poor design of the clock in the limits of temperature, voltage deviation or the manufacturing process will result in th
17、e case wrong, and debugging difficult, spending a lot. In the design of FPGA / CPLD clock when several types of commonly used. Clock can be divided into the following four types: global clock, clock gating, multi-level logic clock clock and volatility. Multi-clock system to include the above-mention
18、ed four types of any combination of the clock. No matter what methods are the real circuit clock tree can not achieve the ideal assumption that the clock, so we must be based on an ideal clock, the clock real work to build a model to analyze the circuit, so as to make the circuit performance and the
19、 practical work as expected . Clock in the actual model, we have to consider the spread of clock-tree skew, vertical jump and absolute bias and other uncertainties. To register, the clock was working along the arrival of the data terminal when it should have been stable, so as to ensure that the wor
20、k along the sampling clock to the accuracy of the data, this data preparation time that we call set-up time (setup time). Data should also be working along the clock to maintain over a period of time, this period of time known as the hold time (hold time). Global clock for a design project, the glob
21、al clock (or clock synchronous) is the simplest and most predictable clock. In the PLD / FPGA design of the clock the best options are: by a dedicated global clock input pins of a single master clock-driven clock design projects to each flip-flop. As long as possible should be used in the design of
22、global clock projects. PLD / FPGA has a dedicated global clock pins, the device is directly connected to each register. Global clock to provide such a device in the shortest possible delay to the output clock. Clock-gated in many applications, the entire design of the overall use of external clock i
23、s not possible or practical. With the product of PLD logic array clock (that is, the clock is generated by the logic), to allow arbitrary function alone all trigger clock. However, when you use the array clock, the clock should be carefully analyzed the function, in order to avoid glitches. Usually
24、constitute the array clock clock-gated. Clock gating often interface with the microprocessor, and used the address to write to control the pulse line. However, when using combination of flip-flop when the clock function, usually there is a clock-gated. If the following conditions, such as clock gati
25、ng can be as reliable as global clock work: Drive the clock logic must contain only one and the door or a or gate. If any additional work in some state of logic, the competition will be the burr. A logic gate input as the actual clock, and the logic gate must be of all other input as the address or
26、control lines, in relation to their compliance with the establishment and maintenance of clock time bound. Multi-level logic generated clock when the clock-gating logic of the combination of more than one (or more than the individual and doors or or gate), the evidence of the reliability of the desi
27、gn of the project has become very difficult. Even if the prototype or simulation results show that there is no static dangerous, but in fact the risk may still exist. In general, we should not use multi-level combinational logic to clock the flip-flop in the PLD design. Traveling-wave clock clock an
28、other popular use of traveling-wave circuit is the clock, that is, the output of a flip-flop used as a clock input of another flip-flop. If careful design, traveling-wave clock can be the same as the global clock to work reliably. However, the traveling-wave clock made from time to time with the cal
29、culation of the circuit becomes very complicated. Line-wave traveling-wave clock flip-flop of the chain have a greater clock time between the offset and exceed the worst case the set-up time, hold time and clock to the output circuit of the delay, allowing the system to the actual slowed down. Multi
30、-clock system, many system requirements within the same multi-PLD clock. The most common example is the two asynchronous interfaces between microprocessors, or microprocessors and asynchronous communication channel interface. As the clock signal between the two requirements to establish and maintain
31、 a certain time, so that the above application from time to time the introduction of additional constraints. They also requested that some asynchronous synchronization signal. In many applications, only the synchronization of asynchronous signals is not enough, when the system of two or more non-hom
32、ologous clock, the data it is difficult to establish and maintain the time to be assured that we will face the complex matter of time . The best way is to all non-homologous clock synchronization. PLD internal use of the lock loop (PLL or DLL) is a very good, but not all of PLD with a PLL, DLL, and chip PLL with most expensive, so unless there are special requirements, the general occasions PLL can not use with the PLD.At this time we need to take to enable the use of the D flip-flop-side, and the introduction of a high-frequency clock.
