Design of LED Lighting Control System Based on AVR

introduction

LED lighting has entered the home user. Compared with traditional lighting equipment (such as incandescent lamps and fluorescent lamps), it has the advantages of high monochromatic purity, diverse colors, high efficiency and adjustable light intensity. Aiming at the problem that the traditional illumination brightness is not easy to adjust and the switch position is fixed, this paper designs an LED remote control illumination system based on AVR single-chip microcomputer, and proposes the method of driving and brightness adjustment of LED illumination lamp.

1 LED lighting control system principle

The system schematic is shown in Figure 1. When the infrared receiver receives the infrared remote control signal, the AVR MCU wakes up from the sleep mode through an external interrupt; the AVR MCU starts to parse the infrared signal, and if it matches the system address, it will change the LED constant current source drive according to the parsed command. Input to change the state of the LED light.

2 system hardware design

2.1 Controller

The controller uses the AVR microcontroller ATmega8. ATmega8 is an AVR microcontroller introduced by Atmel in 2002 in a small pin package. ATmega8 integrates 8 KB programmable F1ash, 512-byte EEPROM and 1KB internal SRAM; 3 PWM channels for any PWM pulse width modulated output less than 16 bits, phase and frequency adjustable; 1 programmable serial USART interface supports synchronous, asynchronous and multi-machine communication automatic address recognition; 5 power saving modes. In this system, the main function of the controller ATmega8 is to analyze the infrared signal and control the LED driver.

2.2 Infrared receiving module

The main components of the infrared receiving module adopt IRM-2368V, which is commonly used in remote control of home DVD, TV, air conditioner and other home appliances. IRM-2368V has the following characteristics: working voltage is 2.4 ~ 6 V; high sensitivity, strong anti-interference ability; can directly extract the remote control signal from the carrier, output matching TTL, CMOS level, can be directly interface with the microcontroller; The remote control distance can reach 12m. Figure 2 is a schematic diagram of the infrared receiving module. Among them, PD2 is multiplexed into ATmega8's external interrupt INTO, and the power supply part uses the system's 5 V power supply.

2.3 LED driver module

The LED driver module uses the HV9910 integrated chip. It has the following characteristics: high energy efficiency over 90%; wide voltage input of 8 ~ 450 V; output current adjustable from a few mA to 1A; can drive up to 100 LED lights; PWM regulates current. Figure 3 is a schematic diagram of the LED constant current source driving, which is a typical buck-boost converter design. The input power supply voltage Vin=12V in the driver drives 3 to 6 3 50mA high-brightness LED lights.

When the HV9910 is operating, the internal oscillation frequency fosc is determined by the resistance on the pin Rosc. In this design, Rosc takes 470 kΩ and sets the gate switching frequency of MOSFET Q1 to 50 kHz. R osc and fosc satisfy the following relationship (Rosc units are kΩ):

Each LED lamp operates with a voltage drop of approximately 3 V. When three LED lamps are connected in series at the output, the driver output voltage is Vled = 91 V. The duty cycle D of the control signal of the Q1 tube can be obtained when the LED is full current:

Q1's on-time Ton=D/fosc=8.6μs, output current Iled=350 mA, harmonic current suppression within 30%, then the value of inductor L1 can be obtained from:

In this scheme, L1 actually uses 1 mH.

The feedback voltage on R1 is compared with the internal comparison voltage of 250 mV of HV9910. If the feedback voltage is greater than 250 mV, Q1 is turned off. R1 can be obtained from the harmonic current relationship:

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Application field:

Method of use: the best stable in horizontal plane, installed on the Gear Reducer Motor output shaft parts, cannot use a hammer to knock,knock prone to press into the gear Reducer Motor drive, may cause damage to internal components, and cannot be used in the case of blocked.

Operating temperature range:

Gear reducer motor should be used at a temperature of -10~60℃.

The figures stated in the catalog specifications are based on use at  ordinary room temperature catalog specifications re based on use at ordinary room temperature  (approximately20~25℃.

If a geared motor is used outside the prescribed temperature range,the grease on the gearhead area will become unable to function normally and the motor will become unable to start.Depending on the temperature conditions ,it may be possible to deal with them by changing the grease of the motor's parts.Please feel free to consult with us about this.

Storage temperature range:

Gear reducer motor should be stored ta a temperature of -15~65℃.

In case of storage outside this range,the grease on the gearhead area will become unable to function normally and the motor will become unable to start.

Service life:

The longevity of gear reducer motor is greatly affected by the load conditions , the mode of operation,the environment of use ,etc.Therefore,it is necessary to check the conditions under which the product will actually be used .The following conditions will have a negative effect on longevity.Please consult with us should any of them apply.

●Use with a load that exceeds the rated torque

●Frequent starting

●Momentary reversals of turning direction

●Impact loads

●Long-term continuous operation

●Forced turning using the output shaft

●Use in which the permitted overhang load or the permitted thrust load is exceeded

●A pulse drive ,e.g.,a short break,counter electromotive force,PWM control

●Use of a voltage that is nonstandard as regards the rated voltage

●Use outside the prescribed temperature or relative-humidity range,or in a special environment.

●Please consult with us about these or any other conditions of use that may apply,so that we can be sure that you select the most appropriate model.

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