Design and development of soybean milk machine control panel

As an economical and healthy food, soybean milk is more and more popular among people. This article introduces the intelligent automatic household soybean milk machine with the AT89C2051 single-chip microcomputer as the core control component. It can choose separate crushing, separate cooking or fully automatic operation. It adopts fuzzy control technology and integrates beating, cooking, protection and warning. It can be convenient , Quickly make cooked soybean milk that is hygienic and fits your personal taste.

1. The structure and working principle of the intelligent soybean milk machine

The processing of soybean milk mainly includes two processes of crushing and beating and heating and boiling. The traditional processing method separates the two processes, that is, it is pulverized first and then heated. There are problems such as complex manufacturing process, low pulp yield, easy overflow of heating and difficult control of heating time. The intelligent soymilk machine adopts microcomputer fuzzy control technology, simulates manual operation, and automatically controls beating and boiling, making the complicated traditional production process easy to use.

The intelligent soybean milk machine we designed is mainly composed of high-speed series excitation motor, heating tube, net cover, temperature sensing probe, anti-overflow electrode, single-chip microcomputer control panel, control buttons, and sound and light alarm devices. The high-speed series-excited motor is responsible for pulverizing and beating, the heating tube is used to heat and boil the pulp, the temperature-sensing probe is used to measure the water temperature, the anti-overflow electrode prevents the soybean milk from heating and overflowing, the buzzer and two-color lamp are used for sound and light alarm, and the control panel is based on the command and input status Signal, fuzzy control, each component is automatically completed according to the program for heating, crushing and other series of work.

Based on the results of repeated trials, we have determined the best process for making soymilk, and combined with the characteristics of each component of the soymilk machine, we have determined the following design scheme:

(1) Smash. The working speed of the series-excited motor can reach about 12kr/s, and the beans can be completely crushed in about 1 minute. However, since the motor cannot run continuously for a long time, the crushing time is divided into four 15s, and the intermittent stop is 15s. In order to improve work efficiency, make full use of the intermittent time of crushing to heat soybean milk.

(2) Heating. The heating is divided into three processes: "pre-heating before crushing", "intermittent heating for crushing" and "heating for pulp cooking". The "heating process of cooking pulp" is timed from the first boiling after pulverization, which takes about 5 minutes. "Pre-heating before pulverization" is to heat the water temperature to 80 ℃, shorten the time of heating to the boiling of soybean milk after pulverization, and prevent the phenomenon of sticking caused by too long cooking time after pulverization. Better results.

(3) command input. Command input adopts three keys of "start Π stop", "heating" and "crushing". After the soya-bean milk machine is powered on or in the stopped state, press the "Start Π Stop" button for fully automatic operation, press the "Heat" button for separate heating for 5 minutes, and press the "Crush" button for separate crushing for 15 seconds; During the working process of heating alone or crushing alone, if you press the "start Π stop" button, all operations will be stopped and it will return to the initial state.

(4) Sound and light alarm. In order to make it easier for people to monitor the entire working process, when the working state is switched, there are traffic light displays and buzzer prompts, and the sound and light alarms ten times after the work is completed. If there is any dangerous operation during the working process, an audible and visual alarm will also be given.

(5) Safety requirements: After power-on, judge the water level to prevent adding too much water; during the whole working process, detect the water level in real time to prevent dry burning without water.

(6) The software and hardware anti-interference technology is adopted to improve the stability of the system work. In terms of hardware, filter circuits are mainly used to suppress interference sources, and WDT monitoring circuits prevent program confusion and crashes caused by interference. In the software, technologies such as code filling technology, instruction redundancy technology, setting module entrance signs and intelligent restoration of the scene are mainly used to cooperate with hardware to enhance the anti-interference ability of the system.

2. Soymilk machine circuit design

The design of the hardware circuit mainly includes six parts: the power supply part, the central processing unit, the monitoring circuit, the signal detection circuit, the control circuit and the man-machine interface circuit.

(1) The power circuit uses a 12.5V transformer to transform the voltage, then rectifies and filters, and then obtains a +5V working power supply through a 7805 voltage regulator tube.

(2) The central processing unit is the minimum application system of single-chip microcomputer with AT89C2051 as the core.

(3) The external monitoring chip IMP706 is mainly used to complete the generation of reset signals during power-on, power-off or manual situations.

(4) Signal detection circuit, Rx is the resistance value of the temperature sensing probe or soybean milk solution. The water temperature detection is based on the jump of the resistance value of the temperature sensing rod at about 80°C, and the high and low levels are respectively generated through the comparison circuit, which is provided to the central processing unit. The water temperature signal is provided to the central processing unit; The on-off state of the circuit composed of the shell and water (soymilk) is respectively generated by the comparison circuit to provide high and low levels, which are provided to the central processing unit as a signal of whether there is water or not; whether the overflow is detected is detected by the temperature-sensing probe shell, the anti-overflow electrode and the soymilk The on-off status of the loop is generated by the comparison circuit to generate high and low levels, which are provided to the central processing unit as an overflow or non-signal.

(5) The control circuit controls the on-off and closing of the DC relay through the drive of the triode, so as to realize the control of the operation of the motor and the heating of the heating tube.

(6) Man-machine interface circuit includes command input circuit, indicator light display circuit and buzzer alarm circuit.

3. Soymilk machine control program design

The system software is written in MCS251 assembly language and consists of main program, reset analysis and processing program, command input program, beating program, cooking program, status display and reminder program, etc. Use the AT89C2051 internal timer to set the basic time unit, realize the working order and time constant of each component by software programming, and control the work of each component by setting 1 or clearing the corresponding pin. During the whole working period of the program, the water level is judged. Once the water level is lower than the warning line, it will enter the alarm program and stop the heating and crushing operations at the same time. In the process of fully automatic or separate crushing and heating, if the start/stop button is pressed, all work will be stopped until a new button is pressed.

In particular, the anti-interference software design using the monitoring circuit, that is, the analysis and processing after reset, and the recovery field technology. Because in actual work, since the motor is an inductive load, the moment of start and stop of the smashing operation will cause strong interference to the system, often causing program disorder and even crystal oscillator stop vibration. At this point, the monitoring circuit will provide a reset signal to the system, forcing the system to reset and start working again. In order to avoid the embarrassing phenomenon of the program repeatedly running from the beginning caused by the system reset, it is necessary to have the intelligent recovery technology of the software, so that the program can cut into the breakpoint after the system reset and continue to work normally.

Summarize

Repeated tests have shown that the intelligent soybean milk machine is easy to use, and it can make real-time judgments and responses to key operation commands, anhydrous dry boiling, and heating overflow. The work process is smooth and smooth, and it operates as originally designed. Since the entire working process is fully controlled by the program, it is easy to adjust the relevant instructions and time constants according to different hardware and requirements to achieve the best operating effect. The product has been put into the market and has been welcomed by consumers.

The above is the development example of the intelligent soybean milk machine control system introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have soymilk machine control panel design requirements, you can trust us. We represent a variety of single-chip microcomputers, voice chips, dual-mode Bluetooth ICs, and wifi chips. Brands include Songhan MCU, Yingguang MCU, Jerry Bluetooth, Ankai Bluetooth, Allwinner, and Realtek. Our technical services include: PCB design, MCU development, Bluetooth solution, software and hardware custom development, APP development, small program development, WeChat official account development, etc. It can also undertake the design of intelligent electronic products, the development of living appliances, the research and development of beauty equipment, the application of Internet of things platform, the smart home control system, the development of TWS earphones, Bluetooth earphone speakers, the development of children's educational toys, the design of electronic education products, etc.