The voice control circuit is designed with 555 timer, which requires 5v power supply and can be adjusted from 5 to 10 second.

Design and Implementation of Multifunctional Timer Based on Single Chip Microcomputer

abstract

This paper designs a design scheme based on AT89.

C5 1 as the core and connection point

Compact and fully functional multipurpose timer. You can use a small key.

Disk input any timing time, the maximum timing is 10h, which can meet various requirements.

Level defense, various competitions and some special timing requirements. Article right

Its structure is introduced.

Keywords: AT89

C5 1, timer, Intel

8279, Intel

8253

1

guide

word

There are usually two types of "timers". One is module-based.

Quasi-technology traditional product, this timer has simple function, although it has been

Widely used, but has been eliminated. The other is based on numbers.

The new generation product of Chinese character technology has powerful functions and is the replacement product of the former.

Substitute. But most of these products are large equipment, really.

Practical, portable and fully functional "main road" goods are rare.

Yes With the continuous improvement of cost performance of single chip microcomputer, a new generation of products

Its application is more and more extensive, which can constitute complex industrial process control.

System, complete complex control functions, small can be used for home electronic control.

The system can even be used to make children's electronic toys. It is powerful and physical.

Small size, light weight, flexible and easy to use, with the appropriate interface chip, you can

Build various microelectronic products with different functions. In view of this, we

A multifunctional timer based on single chip microcomputer is designed and developed. such

Timers other than AT89

Except C5 1 chip, only Intel is used.

Intel 8253

8279 is the main chip, which is a typical "three-chip system"

Unification. " It has the advantages of low cost, full function, high overall cost performance and small matching.

Keyboard and LED display screen can be used for timely alarm in various occasions.

Use.

2

hardware construction

AT series single chip microcomputer is manufactured by ATMEL company in Intel.

New products developed based on MCS-5 1 single chip microcomputer technology,

On-chip 4k

E2ROM, programming/erasing are all realized by electricity.

(there are 5V and 12V modes), which can be used for online programming and erasing.

Telephone lines can also be used for remote programming and erasing. Repeatability is so strong that

Long service life, erasable for more than 1000 times and fast erasing speed.

Come on, it takes about 3s for 4k programming, and only 10ms for erasing. When the program is saved

Max 100 year, Intel

MCS-5 1 Series Single Chip Microcomputer

Fully compatible, with super encryption function, it can completely replace Intel.

mcs

-

875 1/ Intel

mcs

-

8752 and Intel

mcs

-

87c 5 1/ Intel

MCS-87C52, low voltage, low current and low power consumption.

Consumption, in addition to dipping, PLCC, QFP and other packaging forms, there are also

Commercial, industrial, automotive, military and other specifications. because

At present, it is more and more used in the development of microcomputer products.

"Fire". Our system does not need complicated calculation, and the amount of program code is not large.

Big, 4k

ROM is enough, and there is no need to expand ROM and RAM.

Due to AT89

The internal counter of C5 1 is 16 bits, even if

Using a 2MHz clock, the total time is 767.5 μ s, so connect.

Guo Intel

8253 extended counter, using AT89.

C5 1

ALE output is used as the clock pulse of 8253, which is greatly expanded.

The measuring range has been expanded.

Through Intel

8279 expanded its keyboard/monitor because of Intel.

8279 has its own key jitter elimination circuit and key value automatic scanning circuit.

Therefore, there is no need for programming, which not only improves the reliability, but also reduces the

The whole program has less code.

The keyboard is a 4×4 physical key array (some keys are multiplexed), except

In addition to the number keys 0~9, there are also timing keys, modification keys, confirmation keys and setting keys.

Key/Reset, Write, Left and other function keys. See figure 1 for the arrangement of key positions. because

In order to choose plastic film buttons (customized), they are dustproof and beautiful.

The display screen uses 5-digit high-red LED tubes to indicate hours, minutes,

The reason why seconds don't choose liquid crystal is mainly from a wide range of practical environment.

Consider that, for example, ball games are mostly held outdoors, while LCD is.

It seems that the brightness is not enough. In addition, four light emitting diodes are used as time.

The separator between minutes, minutes and seconds is shown in Figure 2.

When the scheduled time arrives, the sound and light alarm at the same time, using high brightness.

LED and required voice (time is up, please stop). CPU pair 8279

The monitoring of 8279 adopts inquiry mode, so the interrupt request signal of 8279

IRQ is hanging in the air.

The system has DC (4 knots 1 battery) and alternating current (220 volts).

Electricity) two power supply modes. The rectifier power supply is assembled with the system.

three

software structure

The working clock of 8253 is ALE, and the output is 1MHz. it has

Three counters, in order to maximize the timing range, three

The counter adopts the "apply" method, that is, the output of counter 0 is

Is the input pulse of the counter 1, and the output of the counter 1 is the count.

The input pulse of counter 2 is finally input to the output of counter 2.

The structure of the whole system is shown in Figure 3.

89 years old

Calculate the T0 of C5 1, which is a "hardware timing cycle".

Period "can be timed as 765,438+0 minute 65,438+0.465,438+0 second, which can satisfy general events.

Timing needs it. From a broader perspective, different "soft definitions" have been compiled.

When the "delay program" starts, you can start the "hardware timing week" in a nested form.

Period ",in order to achieve a longer timing needs, but the number of digits displayed has been

Yes, the longest timer can be 10h, which is long enough.

The system software is divided into three modules, namely initialization module and keyboard scanning module.

Description/display module, time delay (pulse counting) module. key technology

In order to calculate the delay time and program 8279, the work cycle should be dynamic.

The countdown time is clearly displayed, and the structural block diagram is shown in Figure 4.

four

Concluding remarks

The multi-purpose timer introduced in this paper is ingenious in design and small in size.

Low cost, strong function, wide timing range, wide use and simple operation.

Convenience is an ideal timing tool, which has been improved after many experiments.

Basic stereotypes. The system has broad market prospects and obvious economy.

Benefit.

join

examination

writing

gift

1

Zhang Youde et al. Principle, Application and Practice of Single Chip Microcomputer. Shanghai: Fudan University.

News, 1992

2

Li Hua.

Practical interface technology of MCS-5 1 series single chip microcomputer. Beijing: Beijing

University of Aeronautics and Astronautics Press, 1993

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Interface technology of single chip microcomputer and its application in industrial control. Shanxi(Province)

West: Shaanxi Electronic Editorial Department, 199 1

four

Chen jianduo Principle and application technology of 8098 single chip microcomputer. Beijing: Electronic Industry

News, 1995