CN108770127A - A kind of multi-functional LED desk lamp based on STC89C52 single chip control - Google Patents

Abstract

The invention relates to a multifunctional LED desk lamp controlled by a STC89C52 single-chip microcomputer, which is characterized in that it includes a core control unit built by the STC89C52 single-chip microcomputer chip, and the core control unit is respectively connected to a liquid crystal display drive circuit, a constant current drive circuit, and a temperature detection circuit in real time. clock circuit. The present invention: 1) adopts PWM dimming technology; 2) ensures stable output of high-power LED terminals; 3) uses LCD12864 liquid crystal screen, which can simultaneously display year, month, day, week, hour, minute, 4) Use the DS18B20 temperature chip to detect the temperature of the surrounding environment; 5) Introduce the clock chip DS1302 to avoid resetting the time after power failure; 6) Equipped with a source buzzer , as an alarm clock for alarm signals and user reminders.

Description

A Multifunctional LED Desk Lamp Controlled by STC89C52 Single Chip Microcomputer

technical field

The invention relates to a multifunctional LED desk lamp based on an ATC89C52 single-chip microcomputer, which belongs to the application of the single-chip microcomputer in the field of LED desk lamps.

Background technique

With the continuous progress and development of social science and technology in the 21st century, the electronics industry is showing a trend of vigorous development. There are many existing commercialized LED desk lamps at present, but most of them have a single function. There are many kinds of lamps and lanterns sold in the lamp market. Generally, desk lamps are powered by 220V AC power supply, fluorescent tubes and incandescent bulbs are used as light sources, and controlled by manual switches or touch-sensitive switches.

Most of the products on the market now have only one brightness, which cannot be adjusted according to people's needs. Too bright will waste energy and damage people's eyes, and too dark can no longer meet people's needs. Later, there were also LED desk lamps with adjustable brightness, but most of them were mechanically adjusted. With the development of LED desk lamp products, some multi-functional products have also appeared, such as the combination of desk lamp and clock, the combination of desk lamp and alarm clock, etc., but many products are not satisfactory and cannot meet the needs of modern people for intelligent products. .

Contents of the invention

The purpose of the invention is to change the brightness of the white LED lamp on the desk lamp by changing the output current of the system, and make the desk lamp have multiple functions.

In order to achieve the above object, the technical solution of the present invention is to provide a multifunctional LED desk lamp based on the STC89C52 single-chip microcomputer control, which is characterized in that it includes a core control unit built by the STC89C52 single-chip microcomputer chip, and the core control unit is respectively connected to the LCD drive circuit , constant current drive circuit, temperature detection circuit and clock circuit, wherein:

The temperature detection circuit adopts the temperature sensor DS18B20, and the core control unit only controls the temperature sensor DS18B20 through one I/O port;

The liquid crystal display drive circuit adopts the liquid crystal circuit composed of LCD12864 liquid crystal display;

The core control unit drives the LED lights through a constant current drive circuit, the constant current drive circuit uses a constant current chip CAT4106, and the PWM interface of the constant current chip CAT4106 is connected to the core control unit;

The clock circuit adopts the clock chip DS1302.

Preferably, a resistor and a capacitor are connected to the reset pin RST of the STC89C52 single-chip microcomputer chip, the other leg of the resistor is connected to the ground, and the other leg of the capacitor is connected to a +5V voltage source, thereby forming a charging and discharging circuit, a charging and discharging circuit It is connected in parallel with one end of the reset button, and the other end of the reset button is connected to a +5V voltage source.

Preferably, the core control unit is connected with a buzzer.

A multi-functional LED desk lamp based on the STC89C52 single-chip microcomputer control of the present invention builds a core control system through the STC89C52 single-chip microcomputer chip, and at the same time applies PWM dimming technology to change the brightness of the white LED lamp by changing the output current of the system. In terms of display, an LCD12864 liquid crystal screen is used, which can simultaneously display the year, month, day, week, hour, minute, second and the temperature of the environment, as well as the symbol of the alarm. At the same time, the DS18B20 temperature chip can be used to detect the temperature of the surrounding environment; in order to avoid resetting the time after power failure, a clock chip DS1302 is introduced. In the alarm clock, it is equipped with an active buzzer as an alarm signal and user reminder signal .

The present invention provides a multifunctional LED desk lamp based on STC89C52 single-chip microcomputer control, and its new technical features are:

1) Using PWM dimming technology, the brightness of the white LED lamp can be changed by changing the output current of the system; 2) A constant current chip CAT4106 is added to the drive end of the desk lamp to ensure stable output of the high-power LED end; 3) LCD12864 liquid crystal is used screen, the LCD screen can simultaneously display the year, month, day, week, hour, minute, second and the temperature of the environment, as well as the symbol of the alarm; 4) Use the DS18B20 temperature chip to detect the temperature of the surrounding environment; 5 ) The clock chip DS1302 is introduced to avoid resetting the time after power failure; 6) Equipped with a source buzzer, which is used as an alarm signal and an alarm clock for user reminders.

Description of drawings

Fig. 1 is the overall block diagram of the present invention;

Figure 2 is the minimum system electrical schematic diagram of the single-chip microcomputer built with the STC89C52 single-chip microcomputer as the core;

Figure 3 is a schematic diagram of the connection between the detection circuit and the main control system with DS18B20 as the temperature sensor;

Figure 4 is a schematic diagram of the connection of the temperature sensor;

Figure 5 is a liquid crystal circuit composed of LCD12864 liquid crystal display;

6 is an electrical schematic diagram of a constant current drive circuit;

Fig. 7 is a block diagram of software part design of the present invention;

Figure 8 is a block diagram of the LCD12864 driver;

Fig. 9 is a temperature detection program block diagram;

Figure 10 is a block diagram of the clock program design.

Detailed ways

In order to make the present invention more comprehensible, preferred embodiments are described in detail below with accompanying drawings.

The LED desk lamp of the present invention has multiple functions, and can realize the adjustment of the brightness of the desk lamp under the control of the STC89C52 single-chip microcomputer, and has 6 adjustment degrees. At the same time, the year, month, day, week and time can be displayed on the LCD12864 LCD screen, and under the control of the DS18B20 temperature chip, the temperature of the surrounding environment can be automatically detected, and there is also an alarm setting function.

The overall design block diagram of the present invention is shown in Figure 1.

Host design: The host control system is the smallest system built using the STC89C52RC single-chip microcomputer chip. The power supply circuit is powered by 5V DC power supply. The oscillation circuit provides an internal clock for the microcontroller. The reset circuit is to restart the system when the system crashes or freezes. In terms of software programming, programs are written in C language.

Slave machine design: The slave machine is mainly divided into four parts, which are liquid crystal display drive circuit, constant current drive circuit, temperature detection circuit and clock circuit. Each part is directly driven by the STC89C52RC single-chip microcomputer, and each completes its own function under its control.

The main control chip is a low-power, high-performance CMOS 8-bit microcontroller-STC89C52 produced by STC Company. When an LED is used as a display, it needs to be driven by a constant current, otherwise the LED may burn out due to an excessive current. The present invention uses a CAT4106 constant current chip. The display screen is required to display more characters and symbols, and the resolution is required to be high enough. LCD12864 is selected as the liquid crystal display screen, and the resolution is 128×64 to meet the requirements. High-power LED lamp beads are used for lighting, and the brightness is very high. The temperature sensor used in the present invention is DS18B20 produced by DALLAS Company, which has the advantages of miniaturization, low power consumption, high performance, strong anti-interference ability, and easy configuration with a microprocessor.

Part 1: Hardware Circuit Design

1) Main control circuit

The main control circuit is actually the smallest single-chip microcomputer system built with the STC89C52 single-chip microcomputer as the core, as shown in Figure 2.

The main control system is mainly composed of two parts of the circuit, one is a reset circuit, and the other is an oscillation circuit. The reset circuit has two reset methods, namely power-on reset and button reset. Power-on reset is to connect a 10K resistor and a 10μF capacitor to the reset pin RST of the STC89C52 microcontroller, the other leg of the resistor is grounded, and the other leg of the capacitor is connected to +5V. When the power is turned on, the reset pin RST has enough time to reach the high level, so that it can be reset. The button reset is directly connected to a button in parallel with the reset circuit, and the other end of the button is connected to +5V. When the button is pressed, the reset capacitor discharges, and the RST pin is also pulled to a high level, which can also achieve the reset effect.

The oscillation circuit is another part of the minimum system of the single-chip microcomputer. It is composed of a crystal oscillator and two capacitors. Generally, the single-chip microcomputer has its own crystal oscillator inside. The crystal oscillator plays a very important role in the small system of the single-chip microcomputer. It can provide the needed Clock frequency. Usually, a system shares a crystal oscillator, which is to facilitate the consistency of the clocks of various parts of the circuit. In the STC89C52 microcontroller, the pin XTAL1 and the pin XTAL2 are the I/O ports of the external crystal oscillator, which provide a stable and accurate oscillation frequency for the system.

2) Temperature detection circuit

The connection between the detection circuit and the main control system with DS18B20 as the temperature sensor is shown in Figure 3. DS18B20 uses single-bus technology, which only uses a single signal line, which can transmit both clock and data, and the data transmission is bidirectional. The connection between DS18B20 and the single-chip microcomputer is very simple, only one I/O port is needed to control the DS18B20, and the resource occupied by the single-chip microcomputer is very little. The D0 pin of the temperature sensor DS18B20 is connected with the P15 pin of the microcontroller STC89C52, as shown in Figure 4.

3) LCD circuit

The liquid crystal circuit composed of LCD12864 liquid crystal display is shown in Figure 5. The LCD12864 LCD screen has a total of 20 pins, of which 18 pins need to be connected, and the 16th and 18th NC pins are left floating. GND (pin 1) is directly grounded; VCC (pin 2) is connected to the power supply, and if there is no special instruction, it is generally connected to 5V by default; V0 (pin 3) is connected to an adjustable resistor, usually about 1K, which is used to adjust the contrast of the LCD display; RS (CS) (pin 4) is the data/command selection terminal (serial chip selection), the data port displays data when the level is high, and the data port displays command data when the level is low; R/W (SID) (pin 5) is the read/write Write selection terminal, E (SCLK) (pin 6), when R/W is high level and the enable terminal is also high level, the read data is DB7-DB0, when both are low level, DB7-DB0 The data is written to IR or DR; DB0-DB7 (7-14 pins) is the data port; PSB (15 pins) is the parallel serial port mode selection, parallel at high level, serial at low level; RST (17 pins) ) is the reset terminal, active low; BLA (pin 19) and BLK (pin 20) are the positive and negative poles of the backlight power supply respectively.

There is a busy flag BF inside the LCD12864 LCD screen, which provides internal working conditions. When it is 1, the module is operating internally and will not accept external instructions and data. When it is 0, it is in a ready state and can accept external instructions and data.

4) Constant current drive circuit

The high-power LED lighting used in the present invention is driven by a CAT4106 driver, and the design principle is shown in Figure 6.

CAT4106 constant current chip, the maximum LED power output can not exceed 6W. When designing the circuit, precise control of the drive current can be achieved through an external resistor. The built-in diagnostic function of CAT4106 can be used to automatically adjust the output voltage, and set the minimum and maximum voltage limits, so as to determine the acceptable working range of the LED, drive the LED with the lowest voltage margin, and improve the lighting effect. At the same time, LED open/short and LED pass voltage can be detected. The efficiency of CAT4106 can reach more than 90%. It has a high-frequency PWM interface up to 2kHz and thermal shutdown protection. It is widely used in background lighting and general lighting.

Part II: System Software Design

In the software part, a high-level language such as C language is used to write the program. Since the circuit is more complicated, there are many parts of the program to be written, so the method of partial debugging is adopted, and the program of each part of the circuit is written and debugged separately. , and then integrate them together, write them into the main program for debugging, which is convenient for writing and checking errors, and can greatly improve the progress of programming. The overall design block diagram is shown in Figure 7.

The block diagram of the LCD12864 driver is shown in Figure 8; the block diagram of the temperature detection program is shown in Figure 9; the block diagram of the clock program design is shown in Figure 10.

Claims (3)

1. a kind of multi-functional LED desk lamp based on STC89C52 single chip control, which is characterized in that including by STC89C52 monolithics The key control unit that movement piece is built, key control unit be separately connected liquid crystal display driving circuit, constant-current drive circuit, Temperature sensing circuit and clock circuit, wherein：

Temperature sensing circuit uses temperature sensor DS18B20, key control unit only to control temperature sensing by one I/O mouthfuls Device DS18B20；

Liquid crystal display driving circuit uses the liquid crystal circuit of LCD12864 liquid crystal displays composition；

Key control unit drives LED light by constant-current drive circuit, and constant-current drive circuit uses constant current chip CAT4106, permanent The PWM interfaces of stream chip CAT4106 are connected with key control unit；

Clock circuit uses clock chip DS1302.

2. a kind of multi-functional LED desk lamp based on STC89C52 single chip control as described in claim 1, which is characterized in that A resistance and capacitance, another foot ground connection of resistance, capacitance are connect on the reset pin RST of the STC89C52 single chip chip Another foot connect+5V voltage sources, the charge-discharge circuit being consequently formed, charge-discharge circuit is in parallel with one end of reset key, reset Another termination+5V voltage sources of button.

3. a kind of multi-functional LED desk lamp based on STC89C52 single chip control as described in claim 1, which is characterized in that The key control unit is connected with buzzer.