Industry news

2016August

LED indoor lighting control system based on single chip microcomputer

From: www.szbako.com Data:08/08/2016

Abstract: This paper introduces the design of a LED intelligent lighting control system, and gives the design of hardware and software and the control flow of the system. The system uses STC12C5A60S2 as main controller, by use of a pyroelectric infrared sensor to detect the human body radiation trace infrared, photosensitive resistance detecting environment luminance, the temperature DS18B20 detection of the LED, LED Driver with PWM dimming technology.

0 Introduction

China is a resource scarce country, but in everyday life, people are not aware of this. Indoor lighting, for example, in many public places are using manual switch, often without the timely turn off the phenomenon, thus causing the waste of energy, will shorten the life of lamps . In view of this phenomenon, it is necessary to study a kind of intelligent lighting control system. The system uses intelligent sensor to automatically adjust the light to keep the indoor constant illumination, which can not only make the indoor have the best lighting environment, but also can achieve the effect of energy saving. LED

is called the fourth generation of green light source, LED light emitting device is a cold light source, with energy saving, environmental protection, long life, small size and so on. LED

light is good, the spectrum is narrow, and the color can not be filtered. Under the same lighting conditions, the LED lamp power consumption is 1/10 of the incandescent lamp, 1/2 of the fluorescent lamp, is the future development trend of lighting.

intelligent control scheme design

system using photosensitive resistance detecting environment luminance, pyroelectric infrared sensors to detect human radiation trace infrared, temperature detection module detects such temperature, the sensor detects the signal through the pre processing to the microcontroller, after monolithic integrated circuit processing control switch and the brightness of the LED lamp. The system block diagram is shown in figure 1.

2 hardware design

. Heat release an electric infrared detection module heat lens with Fresnel matching in front of the sensor. The pyroelectric infrared detection module of

is composed of Fresnel lens, pyroelectric infrared sensor (PIR), control circuit and driving circuit. The block diagram of pyroelectric infrared detector is shown in Figure 2.

the human body has a constant body temperature, generally at 37 degrees Celsius, will emit a specific wavelength of 10 μ m about the infrared. Human radiation of infrared light through the Fresnel lens collection of PIR 2 block detectors in. When the movement of the human body, infrared radiation intensity change, detection element surface charge intensity changes, the internal field effect tube amplification have output signal.

pyroelectric infrared detection module uses the pyroelectric special control integrated circuit to deal with, where the use of BISS0001 type integrated circuit. BISS0001

type integrated circuit with independent high input impedance operational amplifier, can be matched with a variety of sensors, infrared signal pretreatment. The chip contains a voltage comparator, a state controller, a delay circuit timer, a blocking time timer, and a reference voltage source. The circuit is shown in figure 3.

2 environment brightness detecting module

2. temperature detection module

DS18B20 temperature measurement system is relatively easy to achieve, first of all, DS18B20 initialization, and then sent to skip the ROM command and temperature conversion, start DS18B20 for conversion. And then re initialization of the DS18B20 parallel matching ROM commands.

in the end, the DS18B20 readings.

2. 4 SCM control module 2. 5 LED drive module

dimming, when the DIM pin voltage is less than 0.3 V off the LED current, higher than 2.5 LED when the V current open. The basic principle of PWM dimming is to keep the LED forward current constant, and by controlling the current conduction and turn off time ratio, that is, control the time of each cycle current conduction. The calculation method is as follows:

through the PWM dimming, LED output current can be changed from 0% to 100%. PWM dimming with respect to the traditional linear dimming, does not affect the efficiency of the LED light. The advantage of PWM dimming is that the current of the forward conduction of LED has been constant, and the chroma of LED will not change as the analog dimming. PWM dimming can accurately control the brightness of the LED at the same time, but also to ensure that the LED luminous color. The

3 software design

system has three modules: 1) signal input module, achieve the corresponding signal to the microcontroller input; 2) signal control module, the signal processing; 3) signal output module, coding output of results of treatment, to control LED brightness. MCU receives the signal, namely passive heat release electric infrared detector output switching signals, visible light detection output of the indoor brightness control signal and the temperature sensor to detect the LED temperature signal, transmitting these signals to the MCU. Through the MCU processing, so as to drive the LED switch and control the brightness. The software flow chart is shown in figure 6.

4 conclusion

have been verified by experiments, and the design of intelligent LED lighting control system, according to the indoor light according to the brightness automatic control switch and the brightness of the LED, achieved the effect of very good energy saving and improve the lighting environment.

the system has the advantages of simple structure, strong practicability, applicable to the apartments, office of the corridor lamp, bathroom lamp and so on.

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