Intelligent Control System of Washing Machine Based on AT89C52 Single Chip Microcomputer

　　High-efficiency, energy-saving, water-saving, electricity-saving and environmentally friendly washing machines have always occupied a dominant position in the market. Whether in terms of quality, technology, function or appearance, they are closest to the purpose of serving people's lives. In the future, washing machines will develop in several directions such as high automation, product diversification, energy saving and health.

　　Single-chip microcomputers are increasingly widely used as control systems for daily household appliances. The intelligent control system for washing machines introduced in this article uses a single-chip microcomputer as the control core, which simplifies the cumbersome operations of previous washing machines and improves machine performance. At the same time, it adds different control functions and improves control accuracy. It combines software and hardware methods to realize the automation and intelligence of washing machines.

　　Overall Design

　　The washing machine panel contains four buttons, seven indicator lights and two LED digital displays. The four buttons are used to control the working mode of the washing machine. The indicator lights work with the buttons. The LED digital display is used to display the washing time and the dehydration time. Turn on the power switch of the washing machine. The strong wash indicator light indicates that the washing machine is currently working in the strong wash mode, that is, the motor only runs in one direction. Select the weak wash mode and press the "increase" key once; then press the "programming selection" key, the "washing times" indicator light will light up, press the "increase" key or "decrease" key to set the washing times; then press the "programming selection" key to set the washing time. At the same time, the "washing time" indicator light will light up, and the dehydration time will be set in the same way; after setting all the parameters, press the "start" key, the washing machine starts to work, and the washing machine automatically divides the washing time set by the user by the washing times to get the water change time each time. During the washing process, the LED digital display shows the remaining time of the washing machine; when the washing time set by the user has arrived, the water in the washing tub is drained, and then the motor is started to start dehydration, and the "remaining time" indicator light will light up, and the LED digital display will show the remaining dehydration time. After the dehydration is completed, the buzzer alarm will sound 5 times to notify the user that the washing is over.

　　hardware design

　　The automatic control of the bundle washing machine is realized by using AT89C52 chip control) through 74LSl38 decoder, water level detection mechanism, inlet/outlet valve, LED digital display, keyboard and other hardware circuits. The circuit schematic is shown in the figure below.

　　AT89C52 supports online programming. The combination of a general-purpose microprocessor and Flash memory allows the Flash memory to be repeatedly erased and written, effectively reducing development costs, greatly simplifying circuits, and making program writing and curing more convenient and flexible.

　　In the above figure, the 8 I/0 ports of the chip's PO and P2 are connected to an LED digital display respectively, PO controls the high bit, P2 controls the low bit, P1.0 and P1.1 control the direction of the motor, P1.2 is connected to the buzzer, high level is valid, when P1.2 is "1", the buzzer alarms, and when it is "0", the alarm stops, P1.3, P1.4 and P15 are connected to the 74LSl38 decoder input terminals A, B, and C, P3.0 and P3.1 control the inlet and outlet valves respectively, P3.2 and P3.3 control the water level detector), P3.4 and P3.5 control the row output of the keyboard, and P3.6 and P3.7 control the column input of the keyboard.

　　The hardware input controls the washing machine control mode and working procedures. There are 7 different indicator lights. 74LSl38 is a 3-8 decoder. The output ends control 7 indicator lights respectively. YO controls the "washing remaining time" indicator light, Y1 controls the "dehydration remaining time" indicator light, and Y2 controls the "strong wash" indicator light.

　　Indicator light, Y3 controls the "weak wash" indicator light, Y4 controls the "number of washes" indicator light, Y5 controls the "washing time" indicator light, and Y6 controls the "spinning time" indicator light.

　　The four buttons consisting of a 2x2 matrix keyboard are used to set the four parameters of strong and weak wash selection, number of washes, washing time and dehydration time.

　　The output control circuit of hardware output control consists of three parts: water inlet valve, drain valve, motor and water level detector. The water inlet and drain valves have two states: open and closed. In the motor drive circuit, P1.0 controls the motor to run forward, and P1.1 controls the motor to run reversely. The strong wash mode selection means that the motor always rotates in one direction, and the weak wash mode means that the motor moves alternately in the forward and reverse directions, changing direction every one minute. The water level indicator F of the water level detector is used to indicate whether the water is full or empty. Interrupt 1 determines the water level through the F value.

　　software design

　　The main program flow chart is shown in the figure below. The software design also includes: external interrupt 0 service program controls the programming state and working mode, external interrupt 1 service program determines the water level state, timer 0 timer wash time and each water change time, timer 1 timer dehydration dl\par time. The system uses a 6MHz crystal oscillator ) Timer 0 and timer 1 are initially set to generate an interrupt every 100ms, the corresponding high-order time constant is OBOH, and the low-order is 3CH. After the washing machine enters the working state, timer 0 starts to control the washing time according to the set value.

　　Press the "Start" button and the washing machine starts working. It is also used as a "pause" button during operation. If the button is not used for programming, increase or decrease for a period of time, the washing machine stops working after the "Start" button is pressed and the working status at that time is retained. When the button is pressed again, the washing machine continues to work.

　　The focus of software anti-interference is the CPU's anti-interference ability. The purpose of anti-interference is to discover how the CPU is interfered with, how to intercept the out-of-control program flow, how to reduce program losses, and how to quickly and accurately restore the system to normal. The most common method is to solve it through instruction redundancy and software traps.