Kneel down and beg for the paper "Design and Manufacture of Simple Washing Machine Controller"

The general idea, basic principle and block diagram of 1 design 4

1. 1 General idea of design 4

1.2 basic principles 5

1.3 system design block diagram 5

2 unit circuit design 6

2. Design of1cm counter and 60-second counter 6

2. Design of1.1minute and second counter 6

2. Circuit diagram of1.2 minute and second counter 7

2.2 second pulse generator 9

2.2. 1 sec pulse generator principle 9

2.2.2 Its schematic diagram is shown below.

3-cycle control circuit 10

3. 1 Introduction to Basic Principles 10

3.2 Its schematic diagram is 1 1.

4 monostable delay circuit 12

4. 1 Its schematic diagram is 12.

5 General control circuit 13

6 Fault Analysis and Circuit Improvement 16

7 Summary and debugging experience 18

8 Appendix (Parts List) 20

9 references 20

The general idea, basic principle and block diagram of 1 design

1. 1 general idea of design

According to the requirements of curriculum design, it is required to realize the forward rotation, reverse rotation and pause of the motor. In fact, the motor is not connected to us. This time, it will be represented by the state of Sige LED lamp. When the display time is 20 seconds before forward rotation, 10 seconds after reverse rotation and 10 seconds after pause, the period is exactly 60 seconds, which is a natural minute counter and seconds. The next pulse is certain, but if there is a minute counter and a second counter, we have to consider whether we need a 60 frequency divider. As far as we know, we have a shift register to realize the loop. One more question. When the washing time is up, the alarm needs an alarm circuit. According to the design principle of humanization, automation and low cost, the alarm buzzer cannot be called for a long time. To have a reasonable time, we can use monostable circuit to realize it. It looks good. It's too early to think so. There is still a problem to be solved: how to extract the signal of time and make the circulating circuit work? There are two schemes: one is to extract the signal directly from the numerical value to control a 74LS194 which can realize the cycle; The other is to complete this minute by cyclic conversion from binary to decimal, but from the complexity and economy of the circuit, it is obvious that the latter is too complicated, which is not conducive to wiring and troubleshooting. Although it will be more difficult and the results will be later than others, it is necessary to design a product that can really reassure users. In particular, the last loop can be easily implemented with two 194. That's about it now. Let's talk about the basic principles first.

The basic principle of 1.2

First, the signal from the second pulse passes through a control circuit and enters the second counter for counting and clearing. At this time, the user inputs the washing time and presses the start button, and the washing machine starts to work. When the second counter becomes zero, borrow the number of the minute counter; At the same time, after the signal of 10 second bit conversion enters the shift register, the LED lamp indicates the running state of the motor; When the washing time set by the user ends, the circuit gives an alarm and clears it; At the same time, the motor indicator goes out.

1.3 system design block diagram

1.3. 1 system design block diagram

2-unit circuit design

2. Design of1decimal counter and 60-second counter

2. Design of1.1minute and second counter

Decimal minute counter and 60-second counter have the same principle, but their input pulses are different from decimal. We use four 74LS 192 blocks to realize the function of minute counting and second counting, and all we want is countdown, so we connect its UP terminal to high level and its DOWN terminal to second pulse. The input terminals B and C of the twelfth bit are connected to the high level, that is, the input terminal of 0 1 10 (decimal 6). The LD of the twelfth bit is connected to the borrowing terminal BO, and then the BO of the second bit is connected to the DOWN terminal of the twelfth bit. When the second pulse is input from the DOWN terminal of the second bit, the second count is turned on at 192.

From 9 to 0; At this time, the borrowing terminal BO will send out an input terminal DOWN at a low level of ten bits per second, and the count of ten bits per second will change from 6 to 5 until it becomes 0; When all the high and low bits are zero, the BO with ten bits per second sends out a low level signal. When DOWN is zero, the LD of the set terminal is equal to zero, and the set of ten bits per second is completed in parallel. When the next falling pulse comes, the counter will enter the countdown work of the next cycle.

The same is true for itemized counting; It is only required that the minute can be automatically reduced when the second count is completed, and the second ten-digit borrowing terminal BO needs to be connected to the downstream end of the minute count as the input signal of the minute count, so as to realize the second borrowing from the minute count. Of course, these counters are all working, in which the clear terminal CR should be low level and the set terminal should be high level when there is no counting. This is an independent timer that can display 10 1 minute at most. Connect all four 192 QA/QB/QC/QD to the external display circuit, and you can see the time display. As a module of the washing machine controller, there must be a certain interface to connect other modules to work together, and the zero clearing end LD of the sub-counter is connected together; The zero-setting terminals LD of seconds are connected together, so a transistor (NPN) or two OR gates can be used to realize this function when zero-setting is forced from the outside. In addition, we can use the upper end of the sub counter to set the external number. When they are connected with a low trigger pulse (usually kept at a high level and input at a low level when there is external force), digital input from 0 to 9 can be realized.

2. 1.2 minute and second counter circuit diagram

2. 1. 1 minute and second counter circuit diagram

2.2 second pulse generator

2.2. 1 sec pulse generator principle

The second pulse generator we need can be composed of an integrated 555 timer. When the power supply is turned on, VCC charges the capacitor by charging R 1 and R2. The voltage obtained on the capacitor rises exponentially. When the voltage on the capacitor reaches 2/3 VDC, the transmission voltage VO is zero and the capacitor is discharged. When the voltage drops to 1/3VCC, the output level is high and the capacitor discharge ends. In this way, the oscillation is formed again and again. The period we want is 1 sec and the frequency is 1 Hz. The period t can be known by the following formula:

T=R 1。 R2lnC (2-2- 1)

2.2.2 Its schematic diagram is as follows.

2.2. Schematic diagram of1sec pulse generator

Three-cycle control circuit

3. 1 Briefly describe its basic principle.

We still use our method to extract the number on the tenth bit of a second as the input signal of the environmental control system, and the number on the second bit is the same and can be ignored. Our goal is to convert the binary number output on the tenth digit in one second into two digits and three digits:

So S 1 state

1 0 moves to the right.

1 flashing

0 1 move left

5 0 10 1 4 0 100

3 00 1 1 2 00 10

1 000 1 0 0000

3. 1. 1 state transition table

Now we connect QA and QB of 192 to an exclusive OR gate, QC to an inverter, and then connect their signals to a NAND gate and then to the So terminal, and input the signals of the inverter to the S 1 terminal; This has achieved the above requirements. We turn on the computer, the counter is cleared, and QA, QB and QC do not output. At this time, the output is 000, 194. Therefore, S 1 is 1 1, and the number of shift registers is 00 10. When the output of 192 is 0 10 1, So and S 1 are 10, and the shift register moves to the right, because both ends of So and S 1 are connected with a NAND gate output 1, and then. Output from node 46, through inverter to node 48, and gate U28 has no output pulse, so 194 moves to the right until the next state comes. Obviously, the same is true when the output of 192 is 0 100. When the output is 00 1 1, the states of So and S 1 are 1, 194 in parallel, and the QB terminal outputs high level1,and at the same time, So and S 1 are connected in parallel. When the node 46 is at the high level of 1, a pulse signal can be output through U28, and the OR gates U22, U23, U24, U25 and U26 of U28 can output the pulse signal to the transmitter.

Photodiode realizes flicker; When the output of 192 is 00 10, the states of So and S 1 change from 1 1 to 0 1, and the shift register 192 shifts to the left under the input of pulse. Like the right shift, the outputs of So and S 1 to U27 are both high levels of 1, so the AND gate U26 outputs a high level; When the output of counter 192 is 000 1, it is still the same as 00 10; Finally, when the output of 192 is 0000, which is the same as the output of 00 1 1, the shift register 194 is set and the LED flashes. At this point, the signal is extracted and the loop is completed.

3.2 Its schematic diagram

3.2. 1 schematic diagram of circulating circuit

4 monostable delay circuit

555 time base circuit is a kind of combinational integrated circuit which skillfully combines analog function and logic function on the same silicon chip. It is novel in design, ingenious in conception and widely used, and is favored by electronic professional designers and electronic enthusiasts. People call it a great small integrated circuit. 1972, Tix Company of Signy, USA, developed Tmer NE555 bipolar time base circuit, which was originally used to replace mechanical time delay devices such as thermal time delay relay with large volume and poor timing accuracy. However, after the device was put on the market, people found that the application scope of this circuit far exceeded the original design scope, and it was widely used in almost all electronic application fields, and the demand was huge. Major companies in the United States have copied this circuit one after another 1974 Signy Tix Company has integrated two bipolar 555 units on the same substrate, named NF556. 1978, Intelsil company of the United States successfully developed CMOS time-base circuit ICM555 1CM556, and later introduced four time-base circuits 558, integrating four time-base circuits on one chip. Due to CMOS technology and high integration, the application of time-base circuit has expanded from civilian to rocket, missile, satellite, aerospace and other high-tech fields. During this period, Japan, Western Europe and other major companies and manufacturers also competed to imitate production. Although the major semiconductor or device companies and manufacturers in the world are producing their own models of 555/556 time base circuits, their internal circuits are similar and all have the same extraction function.

4. 1 its schematic diagram

4. 1. 1 monostable delay circuit

5 universal control circuit

Now that each unit circuit has been completed, it is necessary to combine them effectively to realize the purpose function together. We require that when setting the number of minutes, seconds should be displayed as zero; Externally, there must be a mandatory suspension; There is also a pause function.

For the set number, we can connect a switch between the upper end of the minute counter and the high level. When we give it a low level, the counter will increase by 1. But at the same time, 192 requires that its DOWN terminal should be high level and the second counter should be zero. We can clear the second counter and stop the pulse at the same time. Connect a switch at high level, connect it to a JK trigger, and connect JK of the JK trigger to 1 to realize the trigger function. Let its Q terminal output to the zero-clearing terminal of the second counter, so that the second counter can be cleared just after starting the machine or pressing the start key again. Connect the Q inverting terminal of JK flip-flop and the inverting signal of Bo borrowing terminal of the sub-counter to a NAND gate, and the signal of the NAND gate is connected to the DOWN terminal of the sub-counter, so as to ensure that DOWN is high when the digital is set. However, if this is the only case, when the power-on key is pressed again (JBOY3 in the figure), there is no pulse signal input at the lower end of the second counter, and 192 cannot work. We can connect the Q terminals of the pulse and JK flip-flops to an AND gate, and then connect its upper output to the lower end of the second counter to control the counting. Have a rest first. The problem now is that the circulating LED is not controlled by the control key, so it is necessary to output the control signal of AND gate U 12 to the clock signal CLK of shift register 194.

Finally, we have to solve a big problem. When the set laundry time is over, it will give an alarm and reset automatically. As for the alarm circuit, we know that when the counter is all zero, a borrow signal will be sent from the second bit to the tenth bit, and the tenth bit will send a borrow signal. We can use this signal as an alarm and clearing signal. At ordinary times, the borrowing end of 192 keeps high level, and becomes 0 when there is borrowing signal. We connect a NOT gate at the borrow end of the tenth bit, and then the CLR end of division. It is also necessary to connect a JK trigger (U 10) as its clock signal, and then connect it to the input terminal TRI of the monostable circuit, and the output terminal of the monostable is connected to the buzzer. The other input of the AND gate (U 14) is connected to the control switch J3, and the AND gate is still connected to the JK trigger U9, so that when the laundry time ends, the 0 signal of the borrowing end Bo of the ten-minute counter can be changed to 1 to reach the AND gate U 14 through the above path, and at the same time, the JK trigger U 10 gets a trigger signal and outputs it. At the same time, the 1 signal sent by U 14 makes U9 send 1 signal to clear the second counter; Of course, the Q terminal of U9 didn't output the second pulse because of the 0 signal, so the original flash was no longer on. At this point, a circuit is finally ok. Sometimes we need to have a rest. When we change the laundry amount, we need a pause button. That's ok, just cut off the second pulse. We can connect an AND gate controlled by a switch-controlled JK trigger between the AND gate U 12 and the pulse arrival terminal, so that the pulse output can be controlled. We know that when one input of the AND gate is 0, its output is 0 no matter what happens at the other end, but when one end is 1, whatever the AND gate inputs at the other end can be output. Now the control terminal is also connected, so a complete washing machine control circuit is completed.

5. 1. 1 general circuit diagram

6 Fault analysis and circuit improvement

If you want to get a good design, what you need is always affirmation and negation. After several modifications, a circuit can be affirmed and adopted. Just like a loop, a loop with three interfaces was designed at first. This interface requires the signal output from ten bits per second to be in a state, which can only be efficient. When it comes, it can be said that the circuits that realize forward transmission, reverse transmission and pause are independent of each other. The reaSons are as follows: the high level is coming, let it connect with so and s 194. Among them, an RS flip-flop is connected to the signal received from So, and when the digital output of terminal B, there is a high level on QB, which is connected to a D flip-flop. The signal output by the D flip-flop from the Q reverse terminal is connected to the Q terminal of the RS flip-flop just now to make the Q terminal zero, so that it can move to the left under the control of the pulse, as shown in the circuit connected to the switch 1. Similarly, connect an RS trigger to the circuit input to terminal S 1, connect the signal fed back from terminal 194QB to the D trigger, and connect the signal at terminal Q of the D trigger to terminal S 1, so that it can move to the right, as shown in switch 2. Xunhua should be designed separately. As shown in the figure, the diode is used to ensure that each module can work independently, so that when the high level comes, the number of 194 is set to 0000, and the last state is cleared, whether it is moving left or right. At this time, as long as the switch 1 or 2 is turned on, it will flash under the action of pulse, and the single module demonstration will be ok. But not if it's connected to a circuit. When opening, you can move to the right or blink in the first minute, but you can't move to the left. The LED is blank, but for the next few minutes, you can only see it when it flashes. After several experiments, it is known that there is something wrong with the time switch 3. No matter whether it is 1 or 0, it takes precedence over the number from the terminal of 194Q. When the time switch 3 does not work, it is known that when both ends of the terminal of 194Q are connected with an LED, when the terminal of 194q moves to the right or left, the states of the two LEDs do not work.

The chart is as follows:

7. 1. 1 circuit diagram

7 Summary and debugging experience

1. Through this course design, we have strengthened our ability to do things, think and solve problems. In the whole design process, we designed a set of circuit principle, PCB connection diagram and chip selection through this scheme. In this scheme, four 74LS 192 timers, two 74LS08, 74LS32, 74LS00, 74LS76 and NE555 timers, one 74LS 194 timer and one 74LS86 timer are used.

2. In the design process, we often encounter such a situation, that is, we always think that this connection can work, but we can't connect the circuit, so we spend a lot of time on it.

3. I am so immersed in the curriculum design, which also consolidates and strengthens the textbook knowledge. Because there is too much knowledge in the textbook, we can't understand and use the functions of various components well in the study between classes, and the examination content is limited, so in the course of this course design, we have learned a lot about the functions of many components and their use in circuits.

When reading textbooks at ordinary times, sometimes the questions are always confusing. After the course design is completed, those problems will be solved. You can remember many things. For example, the functions of some chips, usually read textbooks, read this time, and forget next time. Through hands-on practice, we have a deep impression on each component. Knowledge comes from practice, which is the driving force and ultimate goal of knowledge, and practice is the only criterion for testing truth. So the course design before the final exam is very important to us.

4、

Life is like this, sweat indicates the result and witnesses the harvest. Labor is an eternal topic of human existence and life. Only through internship, can I truly understand the true meaning of the word "hard work" and the price paid by the older generation of electronic designers for our society. I want to say that design is a bit hard, but it is also fun. In today's single theoretical study, there are few opportunities for practice, but we can. Design is also a team task. Working together can make us talk and laugh, help each other and cooperate tacitly. How many human joys have been shed here, and the feelings of the university in one year can't keep up with the cooperation in ten days. I feel closer to my classmates. I want to say that I am really tired, but when we see what we have done, we are inevitably excited; As the saying goes, "360 lines, each line is the best." We can also do everything we should for the society. What's wrong with that? We keep asking ourselves. Maybe some people don't like this kind of work, maybe some people think that design work is a bit boring, but we think that no matter what we do, as long as people live a meaningful life. Society needs us, and we can also work for society. In that case, what is the need to lose? So we decided to go our own way and stick to it.

At the same time, I think our work is a team work. Teams need individuals, and individuals cannot do without teams. We must carry forward the spirit of unity and cooperation. One person's departure may lead to the failure of the whole work. It is not enough for only one person to know the principle in the internship. Everyone must know, otherwise one person's mistake may lead to the failure of the whole work. Unity and cooperation is a very important guarantee for the success of our internship. And this internship just trained us, which is also very valuable.

For us, the knowledge gain is of course important, and the spiritual gain is even more gratifying. Frustration is wealth, experience is possession. This internship will definitely be a very good memory of my life journey!

Through this course design, I understand that it is very important to combine theory with practice. Theoretical knowledge is not enough. Only by combining theoretical knowledge with practice and drawing conclusions from theory can we really serve the society and improve our practical ability and independent thinking ability. The problems encountered in the design process can be said to be full of difficulties. After all, this is the first time to do it, and it is inevitable that you will encounter various problems. At the same time, you will find your own shortcomings in the design process, and your understanding of the knowledge you have learned before is not deep enough and your grasp is not firm enough.

The course design was finally completed smoothly, and many professional knowledge problems were encountered in the design. Finally, under the guidance of the teacher's efforts, it was finally solved. At the same time, we also learned a lot of practical knowledge from our teachers. We will thank you next time! At the same time, I would like to express my sincere thanks to all my classmates and instructors who have helped me!

5, this course design, I learned a lot of things that I can't learn in class, such as thinking independently to solve problems, improvising when mistakes occur, and improving with others, all of which benefited a lot. In the future, it should be easier to produce and complete projects with high quality.

6. Here, thank you for your careful guidance and the selfless help of other students!

8 Appendix (Parts List)

Equipment model, purpose and number of introductions

Counter 74LS192 No.4

74LS 194 shift register 1

74LS08 Four 2 Input AND Gate 2

74LS04 Six inverters 1

74LS32 Four 2 Input OR Gate 2

74LS00 Four-2 Input NAND Gate 2

74LS86 Four-2 Input XOR Gate 1

74LS76 Double JK Flip-flop 2

NE555 555 integrated timer 2