Aiming at the problem of inconvenient remote control of ordinary rice cookers, this paper proposes a design scheme of automatic rice cooker based on SIM900A. The optimization and improvement of the mechanical mechanism of the ordinary rice cooker is carried out. The short-interest and GPRS technology is used to realize the remote communication between the STM32F103 single-chip microcomputer and the user mobile phone. The STM32F103 single-chip microcomputer controls the fully automated process of rice cooker from rice picking to cooking according to the user's instruction, and detects the working state of the rice cooker in real time. And intelligent alarm. The test results show that the system runs stably and realizes the remote control of the rice cooker, forming a fast, intelligent and timely cooking mode.
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Nowadays, the rice cooker is developing in the direction of integrating cooking, soup and heat preservation. Although the current rice cooker has the function of making an appointment for cooking, but the appointment time is too long and affects the taste of rice, the automatic rice cooker designed in this paper is embedded and embedded. Technology and wireless communication technology not only realize remote intelligent control of rice cooking, but also ensure a good taste of cooking.
1 How does the automatic rice cooker work?
The designed rice cooker is in standby mode when it is not working. When the SIM900A module receives the SMS or GPRS control command sent by the user's mobile phone, it sends the command to the STM32F103 MCU, and the MCU analyzes the command, and then controls the rice cooker to automatically leak rice and pan. The whole process of rice and rice cooking, and the temperature sensor is used to detect the working temperature of the rice cooker in real time. At the same time, it can intelligently alarm according to the working state of the rice cooker to ensure the reliable and stable operation of the rice cooker. The overall design of the system is shown in Figure 1.
2 Mechanical structure design
This system is a new mechanical structure improvement for ordinary rice cookers, and is designed from three aspects: rice storage device, rice cooking mechanism and rice cooker, as shown in Figure 2.
The top of the device is a rice storage device that can store up to 5 kg of rice at a time. The pressure sensor can accurately measure the amount of rice required for cooking, the solenoid valve controls the in and out of the rice and the water, and the rice-washing mechanism performs the rice-washing operation under the driving of the stepping motor. After the panning, the rice and the right amount are The water is sent to the rice cooker, and then the rice cooker is transported from the idle position to the designated working position by the conveyor belt for cooking, and the robot automatically places the rice cooker lid on the rice cooker under the driving of the motor, and the device is placed on the microwave oven. Automatically controlled under control.
3 hardware circuit design
The hardware circuit of the device is composed of main control circuit, SIM900A wireless communication circuit, sensor circuit, relay circuit, motor drive circuit, power supply circuit, alarm circuit, etc. The hardware circuit is shown in Figure 3.
The main control circuit chip should have high performance, low cost, low power consumption and fast storage speed. This circuit uses ARM core 32-bit single-chip STM32F103 as the control core. It has a wide operating temperature range, 7 timers and 9 communication interfaces. It has 7-channel DMA controller and 2 12-bit A/D modules. Number converter.
The working frequency band of SIM900A wireless data communication circuit is EGSM900 and DSC1800, and the working temperature range is -30～+80°C. It has power saving, fast transmission rate, support packet broadcast control channel, support real-time clock, and support software to control RTS/CTS hardware. Flow control and other characteristics. The SIM900A in this design is used to receive the short message or GPRS control command sent by the mobile phone, and then transmit the command to the STM32F103 chip, thereby realizing the remote control of the rice cooker. The connection between the SIM900A and the controller is shown in FIG. 4 .
The relay is mainly used to control the opening and closing of the solenoid valve and the shutdown of the main power supply of the rice cooker. The working principle is shown in Figure 5.
4 software design
4.1 main program software
The software control flow of the system is: After receiving the external SMS or CPRS command, the SIM900A wireless communication module sends the command to the STM32F103 main control chip, then starts the rice cooker system and monitors the working temperature in real time, and the system intelligently alarms according to the working state, and the STM32F103 controls the rice cooker. Realize automatic leakage, rice, cooking and other functions, the main program flow is shown in Figure 6.
4.2 Software design of the rice leakage device
STM32F103 receives the command issued by SIM900A wireless communication module: If the number of meters required for n people to eat is m1; at this time, the program of the rice eliminator is started and initialized, and the meter quantity of the initialized rice storage device is measured as m2; then the data is sent to the control. The core calculates the difference m3=m2-m1, and then causes the rice eliminator to continue to leak rice and detects the weight m4 of the rice in the rice storage device through the pressure sensor. When m3=m4, the rice storage switch is turned off and the subroutine is returned. In the m2 and m4 values, and ending the program, the flow of the missing rice device is shown in Figure 7.
4.3 Software design of rice digester
The rice eliminator completes the leaking rice movement, and the rice bot starts to work and initializes. In order to reduce the error, the m2 and m4 values ​​returned to the main program are sent to the control center to obtain the actual leakage meter m=m4-m2, and according to m The value is used to adjust the amount of water in the program, and the solenoid valve is controlled according to the timer in STM32F103. The solenoid valve controls the amount of water in the rice washing, and at this time, the amount of water for cooking is controlled by this method. After the rice-washing operation of the rice-washing machine is completed, the solenoid valve is opened to discharge the rice water, and the water discharging time is determined according to the delay program of the STM32F103. A water filter membrane is installed on the solenoid valve of the water outlet to prevent the rice from leaking with water or the water blocking the solenoid valve. The flow of the rice cooker is as shown in FIG. 8 .
5 system test
After the system design is completed, the machine enters the whole machine test stage, and the control command of the rice cooker is remotely sent to the rice cooker. After receiving the short message, the rice cooker analyzes the command, and automatically sets the rice, rice, rice cooking, etc. according to the control mode setting work mode, and simultaneously monitors The working condition of the rice cooker, when the rice cooker is finished cooking or a work failure occurs, a reminder message is sent to the user's mobile phone.
The system tests the two ways of automatic cooking and automatic porridge. The rice cooker sets the working mode according to the SMS control command. In this working mode, the required rice amount and water amount are automatically calculated according to the set number of meals, and Precise control of cooking time. The test program sets the amount of rice required for 1 person cooking mode to 100 g, the increment interval is 100 g, the water addition amount is 2 times the amount of rice, the rice porridge mode requires 50 g, and the increment interval is 50 g. The amount of water added is 4 times the amount of rice, and the amount of rice and the amount of water added are based on the number of people. The cooking and porridge test were carried out 5 times, and each experiment was repeated 3 times. The test results are shown in Table 1 and Table 2. It can be seen from the table that the actual test value of the system is close to the set value, the measurement error is small, and the taste of cooking rice and porridge is good, and the system runs stably and reliably.
6 Conclusion
Based on SIM900A module, the system realizes the functions of remote control rice cooker intelligent rice, intelligent rice, intelligent rice cooking, temperature detection and alarm. At the same time, it adopts mechanical structure such as belt conveyor and robot to assist in the automation of rice cooker. The equipment is cheap, the system is stable, and the control is simple.
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