Design of Electronic Clock Based on Single Chip Microcomputer

Name xx

Student number xx

Class information xx class

Professional electronic information engineering

School of Information Engineering

Lecturer xxx

First, the basis of topic selection

1 purpose of the project

The increasing demand for information exchange and the gradual development of high technology have promoted the development of electronic clocks and put them into the market for wide application.

2 the significance of the topic

2 1 century is the era of rapid development of digital technology, and single chip microcomputer plays an extremely important role in the era of rapid development of digital technology. The development and research of electronic clock is also a top priority in today's information age, because it is used in auditoriums, training halls, teaching rooms, public places and other occasions in schools, institutions, enterprises, troops and other units, and it can be said that it is ubiquitous in people's lives. Therefore, the development of electronic clocks is the need of the country, society and people. Research background With the rapid development of science and technology, time has passed, from watching the sun, pendulum clocks to electronic clocks now, human beings have been studying innovative records. It can time the year, month, day, hour, minute and second, and also has many functions such as leap year compensation. DS 1302 has long service life and small error. Digital electronic clock adopts intuitive digital display, which can display information such as year, month, day, hour, minute, second and temperature at the same time, and also has time calibration function. The circuit is based on STC89C52 single chip microcomputer, which has low power consumption, can work at a low voltage of 3 V, and the voltage can be supplied by 3 ~ 5 V. The calendar has the advantages of convenient reading, intuitive display, diverse functions, simple circuit and low cost, which conforms to the development trend of electronic instruments and meters and has broad market prospects.

Second, the basic content and the main problems to be solved

1 The electronic calendar studied in this subject is a concrete application of single chip microcomputer control technology, and the main research contents include the following aspects:

(1) When choosing an electronic calendar chip, we should focus on devices with practical functions, convenient use, single-chip storage, low power consumption and power failure resistance.

(2) According to the selected electronic calendar chip, the peripheral circuit and single chip interface circuit are designed.

(3) In hardware design, the structure should be as simple, practical and easy to realize as possible, so as to make the system circuit as simple as possible.

(4) According to the hardware circuit diagram, complete the device welding on the development board.

(5) According to the designed hardware circuit, the MCU program for controlling STC89C52 chip is written.

(6) Through programming, compiling and debugging, the program is downloaded to the single-chip microcomputer to run, and the function of this design is realized.

(7) When designing hardware circuits and software programs, we should mainly consider factors such as improving the friendliness of man-machine interface and facilitating user operation.

2 Design report content requirements:

(1) purpose.

(2) Design indicators.

(3) Draw the principle block diagram of the design, and explain the working process of the block diagram and the functions of each module.

(4) Parts list.

(5) Considering the relationship between the clock and the control signal, the workflow is written in the order of testing and verification.

(6) Draw the circuit diagram of each functional module and explain the principle (such as the conversion principle from binary, 5-ary to 10, the conversion from 10 to 6-ary, the selection and conversion of carry signal from unit to ten, etc.). ).

(7) Draw the general layout diagram (the integrated block should be drawn according to the actual layout position, and the data lines from the counter to the decoder and the decoder to the digital tube are simplified diagrams, but the pins of the integrated block should be drawn according to the actual position and marked with names. )

(8) Describe the operation results and operation of the designed and manufactured digital clock.

(9) Summary: Problems and solutions in the design process, experiences in the course design, and suggestions on the contents, methods and requirements of the course design.

3 technical route

1) Collect and consult relevant technical data, digest, absorb and integrate, form various schemes, and conceive, analyze and select more reasonable schemes.

2) Make a choice by analyzing and comparing the schemes, and design the selected scheme.

3) Draw the working schematic diagram and design the program flow chart with proteus.

4) Use software engineering design theory and object-oriented software design method to analyze requirements and design in detail. Using highly standardized and portable language, the software developed in this way can be transplanted to different hardware environments in the future.

5) Write the original program list in a unified standard format to improve the readability of the program.

4 experimental instruments and tools:

1)5V power supply (or experimental box) is shared by 4 people 1.

2) Quadruple bread board 1.

3) 2 oscilloscopes (per shift)

4) 5 multimeters (per shift).

5) 1 tweezers.

6) 1 scissors.

Five experimental devices:

1) The network cable is 2m/ person.

2)*** Six 8-segment digital tubes.

3)CD45 1 1 integrated block 6.

4)CD4060 integrated block 1.

5) 3 pieces 5)74HC390 integrated block.

6)74HC5 1 manifold block 1.

7) 4 pieces 7)74HC00 integrated block.

8)74HC30 integrated block 1 block.

Five10mΩ resistors.

10) 500 Ω resistance 14.

1 1) 2 30p capacitors.

12)32.768k clock crystal 1.

13) buzzer 10 (per shift).

Three. Design Steps and Timetable

(a), functional model, design indicators:

1. Displays hours, minutes and seconds.

2. It can be 24 hours or 12 hours.

3. It has the function of time correction, which can independently correct hours and minutes, and stop carrying hours in branch schools. The timing clock source can be manually input or borrowed from the clock in the circuit.

4. It has the punctuality function. Before punctuality, it starts 10 second, and the buzzer sounds 1 second, and stops for 5 times.

5. In order to ensure accurate and stable timing, the crystal oscillator provides a reference signal of standard time.

(2), design requirements:

1. Draw the overall design block diagram, explain which relatively independent blocks the digital clock consists of, and mark the relationship between each module, as well as the transmission path, direction and frequency changes of the clock signal. And explain the principle in words.

2. Design the circuit diagram of each functional module and explain the principle.

3. Select appropriate components, verify and debug the circuits of each functional module on the bread, and design and select appropriate input signals and output modes during wiring verification. At the same time, the input signal and output mode should be convenient for circuit testing and troubleshooting.

4. On the basis of verifying each functional module, the components and wiring of the whole circuit are rationally laid out, and the wiring of the whole digital clock circuit is debugged. Production requirements: self-assembly, wiring and debugging, and can check and find problems, analyze problems according to principles, phenomena and measured data, and solve them. Problems that students have to solve include those caused by components and bread board faults.

(3), the design report content requirements:

1. Purpose.

2. Design indicators.

3. Draw the principle block diagram of the design, and explain the working process of the block diagram and the functions of each module.

4. Component list.

5. Design the manufacturing process, consider the relationship between clock and control signal, the order of testing and verification, and write your own workflow.

6. Draw the circuit diagram of each functional module, and explain the principle (such as binary, conversion from 5 to 10, conversion from 10 to 6, selection and conversion of carry signal from unit to decimal, etc.). ).

7. Draw the general layout wiring diagram (the integrated block is drawn according to the actual layout position, and the key connections are drawn separately. The data lines from the counter to the decoder and from the decoder to the digital tube can be simplified, but the pins of the integrated block must be drawn according to the actual position and marked with names. )

8. Describe the operation results and operation of the designed and manufactured digital clock.

9. summary. Problems and solutions encountered in the design process, experience in the course design process, and suggestions on the content, methods and requirements of the course design.

IV. Methods and measures

1. The electronic calendar studied in this subject is the concrete application of single chip microcomputer control technology, and the main research contents include the following aspects:

(1) When choosing an electronic calendar chip, we should focus on devices with practical functions, convenient use, single-chip storage, low power consumption and power failure resistance.

(2) According to the selected electronic calendar chip, the peripheral circuit and single chip interface circuit are designed.

(3) In hardware design, the structure should be as simple, practical and easy to realize as possible, so as to make the system circuit as simple as possible.

(4) According to the hardware circuit diagram, complete the device welding on the development board.

(5) According to the designed hardware circuit, the MCU program for controlling STC89C52 chip is written.

(6) Through programming, compiling and debugging, the program is downloaded to the single-chip microcomputer to run, and the function of this design is realized.

(7) When designing hardware circuits and software programs, we should mainly consider factors such as improving the friendliness of man-machine interface and facilitating user operation.

2. Scheme demonstration and selection

Scheme 1: LED LCD screen is adopted, which has powerful display function and can display a large number of characters. The graphic display is diverse and clearly visible, but it is expensive and needs a lot of interface lines, so LED LCD screen is not used in this design.

Scheme 2: Use dot matrix digital tube for display. Dot matrix digital tube is composed of eight rows and eight columns of light emitting diodes, which is suitable for displaying characters. If the displayed figures are too wasteful and the price is relatively high, there is no need to display them.

Option 3: Use LCD. If this option is selected, the power consumption of the system will be reduced, so that it can be powered by batteries and is easy to carry. However, LCD is expensive, the driving circuit is complex and it is difficult to use. To sum up, LED digital tube is more convenient, but liquid crystal can better display data time, so the function is extended to replace digital tube with liquid crystal.

3. Design experience summary:

(1) Students are required to design the schematic diagram according to the principle and chip pin diagram, and verify it step by step according to the wiring sequence.

(2) The easy fault is poor contact.

A) Bend the pin direction of the manifold block in advance, align it with the metal hole of bread board, and then insert it carefully.

B) The stripping length of the conductor is adapted to the thickness of the bread board (slightly shorter than the thickness of the board).

C) Don't expose the conductor's * wire part on the circuit board to prevent short circuit.

D) The wire should be inserted into the center of the metal hole.

(3) When wiring according to the schematic diagram, we must first ensure reliable power supply and grounding.

(4) Note that the control pins of the chip must be connected correctly.

(5) When checking faults, besides testing input and output signals, pay attention to power supply, grounding and control pins.

(6) Pay attention to whether the signal on the pin of the chip is consistent with the signal on the socket on the bread board (the pin of the integrated block is often in poor contact with the bread board).

(7) In order to facilitate the test, the 2Hz signal can be directly input into counters at all levels.

(8) When connected to the timing circuit, analog signal inputs (such as 1Hz and 2Hz) can be connected. After the output signal is switched correctly, the second and decimal carry signals are connected to the timing circuit, and then the timing circuit outputs them to the minute counter and the hour counter.

(9) When the signal is connected from the timing circuit, the original carry signal must be unplugged.

4. Main contents of the study:

The design of (1) system mainly includes the design of display part and digital clock module, and the selection of display interface chip, serial communication chip and power module.

(2) System software design

(3) System debugging and experimental results testing.

Verb (abbreviation of verb) design result

In the whole design process, the minimum system of STC89C52 single chip microcomputer, DS 1302 interface circuit, DS 18B20 interface circuit, alarm clock and liquid crystal display are mainly designed in hardware. In terms of software, with the help of data from various channels, the solar calendar data reading program, solar calendar conversion program, temperature acquisition program, alarm program and LCD display program are mainly designed. The debugging of the system is mainly realized through a STC89C52 development board, and then with the help of Keil, STC and several self-built peripheral circuits. In this process, step-by-step debugging shows the date and time of the solar calendar, as well as the real-time temperature, which is not achieved by centralized debugging.

Periodic effect. The calendar has the advantages of intuitive reading display, diverse functions, simple circuit and low cost, which conforms to the development trend of electronic instruments and meters and has broad market prospects.

The main references of intransitive verbs [3]

Su Ping. Principle and interface technology of single chip microcomputer [M]. Beijing: Electronic Industry Press, 2006:1-113.

Zuo Jinsheng. Electronic and Analog Electronic Technology [M]. Beijing: Electronic Industry Press, 2004:105-131.

[3] Ma Zhongmei, Ji Shunxin. Single-chip microcomputer C language application program design [M]. Beihang University Press, 200 1 year

[4] Lou Ranmiao. Curriculum Design Guidance of Single Chip Microcomputer [M]. Beijing: Beijing University of Aeronautics and Astronautics Press, 2007.7

[5] Zhu Sirong.51Single chip microcomputer realizes the conversion between solar calendar and lunar calendar and week [Z]. Dangdang electronic network

Li Guangdi. Principle and Application of Single Chip Microcomputer [M] Beijing University of Aeronautics and Astronautics Press, 2004 [7] Yueming Wang. Design of Electronic Clock [J]. Heilongjiang Science and Technology Information, 2004

Remarks:

[1] Subject type: product design, process design, scheme design, etc.

[2] Subject source: teaching research, production practice, social practice, simulation, etc.

[3] Journal literature: numbered author. Title [J] Publication name, year, volume (issue): page number. Book literature: numbered author. Title [M]. Place of publication: publishing house, year of publication: page number.