Time setting I 1 gas sensor h~r+l single chip PIC16F8771 sound and light alarm solenoid valve ventilation equipment display notification community security room m total valve I With the improvement of living standards, more and more people are paying attention to indoor safety issues, especially It is a gas leak problem. In recent years, there have been people’s casualties and property losses caused by indoor gas leakage. Although there are some gas alarms on the market, simple alarms cannot solve the problem fundamentally, and it is impossible to timely handle the danger and alarm. Seeking help In order to reduce the loss caused by gas leakage to a higher degree, this paper introduces a smart kitchen gas monitoring system. The system uses the single-chip PIC16F877 as the core, with gas sensors, electronic valves and other components to complete the collection of kitchen gas concentration. Digital display, data processing, sound and light alarm, control actuator and other functions 1 system realization 1 system schematic (see) When a gas leak occurs, the gas sensor will be the gas concentration to the safe concentration, that is, the sensor output voltage exceeds the single-chip microcomputer Gas monitoring system when the voltage value set by PIC16F877 The system starts and automatically performs concentration control and timely alarm; the main functions are as follows: Alarm function: use sound and light alarm to notify the head of the household in time.
Close the gas valve: Close the gas valve in time by the solenoid valve to avoid increasing the concentration of ventilation equipment: Turn on the ventilation equipment in time to reduce the gas concentration monitoring time setting: In order to avoid the system to notify the community security, the system can preset the system processing time (assuming the setting The time is 3min). When the system detects that the gas concentration exceeds the standard, the monitoring system detects that the gas concentration is still exceeding the standard, and then informs the community security to inform the community security: activate the alarm of the security room and simultaneously issue the pre-existing MCU. House information and current gas concentration information, information system 2 hardware introduction PIC series MCU hardware system design is simple, command system design refinement It has the following advantages: PIC series MCU in the structure uses a distinctive design approach. It is neither the program memory and the corresponding voltage of the MC68HCO5/O8 series MCU developed and produced by MOTOROLA to the microcontroller PIC16F877. When the gas concentration exceeds the memory address (that is, the two memories are located in the same logic space, this kind of memory) The structure is called the Princeton architecture. It is not like the MCS? 51 series of single-chip microcomputers that were first developed in the domestic market. The program memory and data memory are independently addressed (Harvard architecture), but they are The information between the CPU and the CPU must share the same bus, and it still cannot escape the bottleneck effect. Therefore, the CPU speed is further improved. The PIC series MCU not only adopts the Harvard architecture, but also adopts the Harvard bus structure. Separating the data bus from the instruction bus inside the chip and using different widths has the advantage of facilitating the "flow-through operation" of instruction fetching, that is, performing the fetching operation of the next instruction while executing an instruction; Achieve single-byteization of all instructions, single-cycle, which helps to improve the speed of CPU execution.
Reduced instruction set (RISC) technology addressing mode is simple, low power consumption, strong driving capability 2.2 Gas sensor Gas sensor is a sensitive device that can sense a certain gas and its concentration in the environment, and converts information about gas composition and concentration. The electrical signal can be detected and monitored by the control system. It can also be composed of an automatic detection, control and alarm system through the interface circuit and the computer. It is an important monitoring device. Various factors such as measurement object and measurement environment, sensitivity, frequency response characteristics, linear range, stability and accuracy should be considered in the selection of gas sensor.
In the system, the concentration of toxic gas should be detected. Because the traditional contact combustion method is easy to cause poisoning, the gas sensor used in this system is MQ-4 electrochemical carbon monoxide gas sensor, which has high gas and natural gas. Sensitivity, low sensitivity to ethanol smoke, fast response recovery, long life, reliable stability and simple drive circuit make it the preferred device for this design. MQ-4 is mainly used in the home. Or industrial natural gas detection device, its working voltage is less than 15V, negative thermal resistance RL is adjustable, the operating temperature range is -10C + 50C, storage temperature range is -20C+70C, applicable measurement range is 300ppm10000ppm because MQ-4 type gas sensor Different kinds of gases have different resistance values. Therefore, when using this type of gas sensor, the sensitivity adjustment is very important. Generally, the sensor is calibrated with 5000ppm natural gas. It is a sensitivity characteristic curve of the MQ-4 type gas sensor.
The test conditions of the curve are: relative humidity: 65% oxygen concentration: 21% sensitivity characteristic curve of MQ-4 type gas sensor Rs (sensitivity surface resistance): resistance value of component under different gases and different concentrations 3 solenoid valve The system meter uses Bosheng BS-S-20 type solenoid valve, which is a special indoor gas pipeline quick-cut solenoid valve. It is a low-voltage DC pulse drive-off type product, which is a safety emergency cut-off device for gas pipelines. The gas leakage alarm system is connected or connected with fire-fighting and other intelligent alarm control terminal modules to realize on-site or remote automatic/manual emergency cut-off air source. The valve body is made of high-quality red copper red; its structure is a new type of double The steady-state, dual-system solenoid valve enhances the reliability and service life of the valve, and its unique small size design makes it small and beautiful. Its technical specifications are as follows: adapting gas: natural gas; artificial gas; liquefied gas and other non-corrosive gas (pulse) action time: less than 1s maximum working pressure: 0. valve closing mode: DC pulse drive manual valve body material: brass alloy stainless steel Aluminum alloy electrical strength: between the conductor and the non-conductor should be able to withstand AC1000V voltage, 1min does not hit the bud and flashover phenomenon. Insulation performance: the insulation resistance between the conductor and the non-conductor should be greater than 100 3 software implementation system software using C language The system main program including the main program of the system and the display subroutine functions to complete the initialization of the system, signal acquisition and processing, gas concentration display, monitoring and overrun alarm, valve closing, and starting ventilation. According to the characteristics of the system work, the program adopts a loop structure, and sequentially queries the alarm input port. When there is an alarm signal input, the program goes to the corresponding block to run. After the operation is completed, it enters the loop flowchart as shown in the iRL (load resistance sense: n coupons, will again buy the supermarket's designated product data from the cash register to the target marketing system server in real time, without changing the cashier's normal operation of the supermarket's original sales system, the system automatically mobilizes the interface, and the data The interface is sent to the target marketing system. When the customer purchases the product with the coupon, the cashier scans the coupon barcode, and the obtained data is transmitted to the target marketing system for verification. If it is legal, the transaction can be performed, otherwise the transaction cancels the interface data. It can be obtained in real time directly from the cash register's sales behavior, and it does not need to be obtained from the retail sales system server. This can ensure the real-time sales data and reduce the complexity of program development, so the interface part is loaded into the cash register.
4 target marketing system interface data interaction The above-mentioned supermarket use marketing system as an example to analyze the behavior of the target marketing system interface data to generate corresponding data interaction, as follows: Before the transaction starts, check whether the target marketing system service is running normally. If normal, the cash register and the target The marketing system communicates; if it is not normal, it does not communicate with the target marketing system, and prompts relevant error information to send the sales flow to the target marketing system after each operation of the data in the normal operation of the target marketing system service (such as If the completion of a commodity entry operation or the cancellation of an item is completed, the success or failure of the shipment will not affect the sales and cash register business.
When paying with the coupon, the cash register sends the coupon verification information to the target marketing system to verify the legality of the coupon. If it is legal, the coupon amount is returned. If it is not legal, an error message is returned, prompting the cashier.
At the end of the transaction, in the normal operation of the target marketing system service, after the payment is over, the cash register will send the transaction end information to the target marketing system. 5 Conclusion In the domestic, the development of the target marketing system is still relatively slow, and we need to accurately locate and learn. Advanced foreign management knowledge, step by step to develop a target marketing system suitable for the status quo of domestic enterprises, and learn from foreign experience, design the necessary system interface part according to the process of the target marketing system. This paper takes the supermarket as an example to analyze the data interaction process of the target marketing system, which can lead to the development idea of ​​the interface and prepare for the interface research and development of the system.
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