1、* - 1 - With the improvement of peoples living standard and life rhythm accelerate, the time requirements of increasingly high, precision digital timing consumption demand is increasing. The production of electronic calendar has many kinds, general to study of multi-function electronic calendar, the
2、 calendar in addition to the original display time, date and other basic functions, also has the alarm, alarm and other functions. Business production of electronic calendar from the quality, price, and practical considerations, constantly improve the design of the electronic perpetual calendar, mak
3、ing it more with the market. The design for the software, hardware with a combination of a set of design. In software design, the hardware part should have relevant knowledge, which helps to design a deeper understanding, contribute to software design. Basic to understand some of the main devices of
4、 the basic functions and role. In addition to using integrated clock chip, and adopts the scheme of MCU, using AT89series single-chip microcomputer made perpetual calendar circuit, use a combination of hardware and software methods, control of LED digital tube output, are used to show the year, mont
5、h, day, hours, minutes and seconds, the main point is: the hardware circuit is simple, the installation convenient and easy to realize, the software design is unique, reliable. AT89C51 is offered by the ATMEL a small microcontroller. 95 years in China market. Its main characteristics is the Flash me
6、mory technology, reduces the manufacturing cost of the hardware, software, fully compatible with the MCS-51, can very quickly by the Chinese majority of user acceptance. This paper introduces the design of the electronic perpetual calendar based on AT89C51. 1 design schemes This article proposed one
7、 kind based on the AT89C51MCU calendar design, the program to AT89C51single-chip microcomputer as a controlling core, and the clock * - 2 - chip DS1302, keyboard, LED display modules and hardware system. In the hardware system with a separate keyboard and LED display, can display a wealth of informa
8、tion, according to the needs of users at any time on time calibration, choice of time, to sum up this calendar is convenient, intuitive display, multiple functions, simple circuit, low cost and many other advantages, comply with the development trend of electronic instrumentation, has broad market p
9、rospect. 2 functional requirements Electronic calendar can dynamically display the year, month, day, week, hour, minute, second. 3 technical feasibility With the domestic large scale integrated circuits, the microprocessor and its peripheral chip had rapid development. Integrated technology most rec
10、ent development is one of the CPU and peripheral chips, such as program memory, data memory, parallel I/O port, serial I/O port, timer / counter, an interrupt controller and other control components are integrated in a chip, made of monolithic computer ( Single-Chip Microcomputer ). But in recent ye
11、ars the introduction of some high-end chip also includes many special function unit, such as A/D, D/A converter, modem, communication controller, phase locked loop, DMA, PWM floating-point unit, output control unit, PWM output when the dead programmable control function. Therefore, so long as the ex
12、ternal expansion circuit and the necessary channel interface can make all kinds of computer application systems, such as industrial production line control system of household appliances, as the main controller, distributed control system terminal node or as its main control node up relay used, data
13、 acquisition system, automatic testing system. The appearance of single chip microcomputer, and the technology in the field of such rapid development, and the single chip computer application system formed by the following characteristics: (1) single chip computer * - 3 - application system has high
14、er reliability. The reliability of the obtained in addition to rely on the chip itself the high reliability and application have the least connection, also can be conveniently made of soft, hardware technology. (2) extension of the system, system configuration is typical, specification, easy to scal
15、e a variety of application system, application system has high utilization coefficient of soft, hardware. (3) in the form of application system is a computer system, a considerable measure, control functions are realized by software, so with flexible features, do not have to change the hardware syst
16、em can properly change system function. (4) have superior performance, price ratio. The 4 chip select The main control chip using51 Series MCU clock chip using AT89C51, American DALLAS company introduced a high performance, low power consumption, with the RAM real-time clock DS1302. Using DS1302 as
17、the timing chip, can achieve accurate timing. More importantly, DS1302can be in a very small current back-up power supply (2.5 5.5V power supply,2.5V power consumption less than 300nA), and DS1302 Can be programmed to select a variety of charging current to power for slow charge, can guarantee the b
18、asic power backup power supply. Display driver using MAX7219, MAX7219 is a microprocessor and a common cathode eight eight LED digital tube display, graph bar / column chart displays or64 dot matrix display interface small serial input / output chip. Sheet including BCD decoder, multiple scan contro
19、ller, word and bit drive and 8x 8static RAM. External resistor only need one set all LED displays current field. MAX7219 and microprocessor only three wires to connect, each show has an address by the digital microprocessor write. Allow users to choose each BCD decoding or not decoding. Users can also choose to shutdown mode, the digital brightness control, from 1 to8to
