introduction
This design will mainly use the single-chip microcomputer as the core to detect the human body signal, and convert the human body detection signal into a level signal that the single-chip computer can recognize. When the single-chip computer recognizes the human body signal, the illumination is turned on, and then according to the strength of the external light. Control the luminous intensity of the lighting device. Once the human detection circuit detects that the environment is unmanned, it immediately transmits a signal to the single-chip microcomputer, and the single-chip microcomputer recognizes and turns off the illumination. Through such control method, intelligent control is achieved, and energy is effectively saved. In order to make the whole system operate reliably, it is necessary to have a good and stable Power Supply system. The design also considers the factors of power take-off and power supply stability and solves these problems.
2 hardware system design
This design has several parts of the system hardware circuit design, including the host circuit, human body detection circuit, resistance voltage conversion circuit, A / D conversion circuit, power circuit several parts. The specific system block diagram is shown in Figure 1.
The STC89C52RC, manufactured by STC, is a low power, high performance CMOS 8-bit microcontroller with 8K in-system programmable Flash memory. Fully compatible with industrial 80C51 product instructions and pins. On a single chip, with a smart 8-bit CPU and online system programmable Flash, the STC89C52RC provides a highly flexible and efficient solution for many embedded control applications.
CS9803 is an integrated circuit designed for pyroelectric infrared sensor (PIR). It is manufactured in CMOS technology and has the advantages of high performance index, good consistency, low power consumption, simple peripheral circuit, convenient installation and debugging, and high reliability. It is a device with better performance and complete functions in the same kind of products. With PIR and a small number of peripheral components, it can form a stable and reliable control system. The CS9803 pyroelectric infrared control IC uses a standard DIP16-pin plastic package structure. The internal system consists of a system clock, a two-stage op amp, a voltage comparator, a detector, a timer, a zero-crossing detector, and an output control circuit. The role of the A/D converter (ADC) is to convert the analog quantity to digital for easy processing by the computer. This design uses the ADC0809 as the main A/D converter. It is a sequential analog 8-channel analog input, 8-bit digital output A/D converter. As the fourth-generation illumination source, LED has the advantages of low operating voltage, low power consumption, high luminous efficiency and long life. Compared with traditional incandescent lamps and fluorescent lamps, the power saving is over 90%. It is considered to be the illumination source of the 21st century.
3 system software design
When designing the overall design of an application system, it is first necessary to clarify the issues that should be considered in the design process:
(1) According to the software functional requirements, the system software is divided into several relatively independent parts. Design a reasonable overall software structure to make it clear, concise, and reasonable.
(2) Each function program is modularized and subprogrammed. It is easy to debug, link, and easy to transplant and modify.
(3) Before writing the application software, draw a software flow chart. This is not only an important part of programming, but also a key part of success. In a sense, spending more time to design a program flow chart can save several times the editing and debugging time of the source program.
(5) Reasonable allocation of system resources. Includes ROM, RAM, timer/interrupter, interrupt source, and more. The most important of these is the allocation of RAM. Because of the C51 programming, the powerful KEIL51 automatically allocates system resources, which is much more convenient than assembly language.
4 Conclusion
This design mainly focuses on how to collect the human body signal with STC89C52RC as the core, then process the signal, and analyze the ambient light intensity, design and control the system, and use the single-chip microcomputer to control the operation of the whole system. For the intuitive display, the method of simultaneously displaying the digital tube and the light-emitting diode is used, and there is a buzzer sound alarm.
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