1 Introduction
At present, in the market electric cooking pot uses the mechanical type or is majority of uses the fixed power the way heating, the energy use factor is low, the function is unitary, meets the life need which with difficulty the people grow day by day. Therefore, the development function is complete, safe reliable microcomputer electric cooking pot right and wrong commonly used essential. Electric cooking pot from mechanical principle to present’s intelligent electric cooking pot, period has experienced many stages. The electric cooking pot display high technology and new technology superiority, cooks a meal take the delicacy boils as the leadership, causes the product even more to enrich with the fashion, already formed the microcomputer, the computer and the machinery three big types, ten big different designs. Although the mechanical electric cooking pot the price aspect manifests outside its superiority, other aspects are very difficult to satisfy the people to the modern life high quality demand. The microcomputer or the computer control the intelligent electric cooking pot meets modern people’s requirement, the user-friendly contact surface design, causes people one to see the current active status, lets you be more relieved, each kind of cooking process completely by computer automatic control, and the intelligent electric cooking pot mostly uses the outer space “the morion” in the gallbladder, ultra hard wear-resisting, permanent artistic, all these characteristics conform to the modern people time-saving, to reduce effort, the durable idea.
This article main introduction comes using the SPMC65P2404A chip to electric cooking pot’s process to carry on the control, SPMC65P2404A is the Ling Yang company’s 8 element monolithic integrated circuit, the highest operating frequency is 8MHz, working voltage 2.5V~5V, some 192 byte RAM and 4K byte OTP ROM, some 23 programmable IO mouth, 8 channel 10 A/D switches, 2 channel 8 fixed time/counters, 2 channel 16 fixed time/counters, 1 12 PWM outlet, has the low voltage, on the electricity, the watch-dog, the external signal, the wrong address replacement, and has a buzzer outlet.
2 Overall concept introduction
Design’s intelligent electric cooking pot control system functional block diagram as shown in Figure 2-1 using Ling Yang 8 MCU, through the pressed key selection function pattern, the display circuit completes the demonstration current condition and fixed time the time; Comes through the temperature sensor to the temperature to carry on the sampling; Realizes finally through the MCU control to the relay the control, thus controls to adds heating platen’s heating or not, the power unit completes to the monolithic integrated circuit system and the peripheral circuit provides the 5V power source, and to adds the heating platen to carry on the heating.
Figure 2-1 control system constitution diagram
3 System hardware design
1st, 3-1 by monolithic integrated circuit SPMC65P2404A control’s electric cooking pot’s hardware schematic diagram as shown in Figure, it including the pressed key input section, the temperature examination input circuit, the replacement and the crystal oscillator electric circuit, PA6, PA7 completes to the roof panel and chassis’s temperature examination, PA5 completes to the relay the control, SPMC65P2404A is system’s hard core.
The click looks at the original map
Figure 3-1 electric cooking pot’s electric circuit schematic diagram
Chip characteristic synopsis
SPMC65P2404A is the Ling Yang company’s 8 element monolithic integrated circuit, the highest operating frequency is 8MHz, working voltage 2.5V~5V, some 192 byte RAM and 4K byte OTP ROM, some 23 programmable IO mouth, 8 channel 10 A/D switches, 2 channel 8 fixed time/counters, 2 channel 16 fixed time/counters, 1 12 PWM outlet, has the low voltage, on the electricity, the watch-dog, the external signal, the wrong address replacement, and has a buzzer outlet ……. Using these resources, can realize electric cooking pot’s function.
2nd, display circuit:
The display circuit is composed of altogether the anode nixietube and 10 LED, elects through the monolithic seat on a plane with the data which delivers to lighten corresponding LED and the nixietube display status. Its electric circuit schematic diagram as shown in Figure 3-2: 
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Figure 3-2 display circuit
3rd, power circuit:
The power unit provides 5V for the monolithic integrated circuit the direct-current constant voltage source, and after the voltage dropping, the rectification, filter’s 14V voltage carries on the power supply to the relay, through control triode emitter’s breakover or not control relay’s active status. Power circuit schematic diagram as shown in Figure 3-3
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Figure 3-3 power circuit
4th, temperature gathering partial circuit diagrams:
J2 and J3 are temperature sensor’s two connections, J2 and J3 respectively are the roof panel and the chassis temperature sensor’s connection, the monolithic integrated circuit examination’s signal in fact is with the temperature sensor differential pressure resistance voltage value, will reduce because of temperature sensor’s resistance value along with the temperature rise, therefore voltage-division resistance’s voltage value had reflected indirectly one time’s temperature, electric circuit schematic diagram as shown in Figure 3-4: 
Figure 3-4 temperature sensor electric circuit
4 System software design
4.1 master routine flows
Designs the overall system approximately from the prototypical analysis, overall system input including 2 temperature sensors, 5 pressed keys; Output including 2 nixietube, 10 light emitter diodes, black-white control signal and so on. According to the control function, the programming is several main modules, the procedure main flow sees shown in Figure 4-1:
4-1 procedure main flow charts
4.2 Subroutine introduction
1st, Diagnosis subroutine
The diagnostic program mainly carries on the temperature to gather and to judge the sensor to be whether good, mainly continuously examines to 2 temperature sensors 20 times, if measures data not in scope (temperature range: - 10℃~160℃), then indicated that the sensor short-circuits or the abruption mistake, the numerical code demonstrated “E”, and forbids the pressed key operation.
2nd, Keyboard scanning subroutine
The procedure circulates a time to scan one time every time the keyboard, if scans has the key to press down, then temporarily stored key value, if continual 5 times scans the key value is the same, then thought that is the stable key value.
3rd, The system altogether has 5 pressed keys, under different condition, each key, so long as presses one time effectively lightly. System’s five keys meet in PA1, PA3, PA2, PA0, PA4, if the pressed key value is effective, then the returns value’s corresponding position is 0, otherwise the corresponding position is 1.
4th, Temperature gathering subroutine
The thermistor sensitivity is high, causes the temperature value change which for the interference protection and other reasons determines to be too quick, causes the control portion frequent movement, temperature gathering uses the glide mean value filter method. Namely gathers three data continuously on the identical channel, takes intermediate quantity.
5th, Demonstrates the subroutine
The system altogether has 2 the nixietube demonstration and 10 light emitter diode demonstration. The nixietube mainly has 6 conditions to need to demonstrate: The readiness for action, makes a mistake the demonstration, to cook rice, the heat preservation, to cook a meal and fixed time the time demonstration. The light emitter diode demonstrated chooses the function, starts and the heat preservation condition. The function demonstrated that must use the wheel to follow the way, before pressing down starts the key, starts the lamp twinkle. After entering the heat preservation condition, keeps warm the indicating lamp to be bright. LED the display sequence by the position code scanning subroutine and the numerical code display status designated that the subroutine composes.
5 Reference
[1] Xiao Jianhua, after is suitable the forest. Fuzzy control in electrical appliances product application and forecast. Wuyi college newspaper (natural sciences version), 2001
[2] Gu Yong. Fuzzy control and application. Knowledge of Modern Physics, 1998.
