Analysis of MSP430 MCU module design

At present, energy shortage has become an important factor restricting social and economic development. How to achieve efficient use of energy is an important issue we face. As a new type of green light source product, LED has the characteristics of energy saving, environmental protection, long life and small size, and its use in real life is becoming more and more extensive. Now the solar panel charging technology has been greatly developed. Many street lights on both sides of the road are charged by solar energy. The existing charging and lighting technologies work according to the pre-set settings and cannot be automatically adjusted according to the changes in the environment. Therefore, the energy utilization rate can be further improved.

In the original charging technology, the angle of the solar panel is fixed, so the angle facing the sun is different throughout the day. This makes solar charging unable to achieve maximum efficiency. If the design system can adjust the angle according to the changes in the sun's position during the day, so that the charging battery panel is always facing the sun and obtains the maximum light, the charging efficiency can be greatly improved. When lighting at night, the brightness of the LED can be adjusted according to the ambient light, which can also save energy.

The MSP430F169 microcontroller used in this system is a 16-bit ultra-low power mixed signal processor produced by Texas Instruments , USA . It has the advantages of ultra-low power consumption, powerful processing capabilities, and rich on-chip peripheral modules, and is suitable for use in some low-power products.

1. Overall system design

The intelligent charging lighting control system is mainly composed of the following modules: light signal detection module, MSP430 single-chip module, motor control and drive module, solar panel charging module, LED lighting module, etc. When the system is running during the day, the light signal detection module will detect the light intensity in different directions to find the maximum light intensity, that is, the angle of sunlight. After the single-chip microcomputer is processed, the rotation of the motor is controlled so that the solar panel can face the light and charge with maximum efficiency. In the evening or at night, the brightness of the external environment is detected by the photoresistor, and the current flowing through the LED is controlled by the single-chip microcomputer, so that the lighting can be automatically adjusted according to the ambient brightness.

2. Analysis and description of each discrete module of the system

2.1 Optical signal detection module

The optical signal detection module mainly uses different phototransistors as sensors to detect the light intensity at different angles of the outside world, and converts the light intensity, a non-electrical quantity, into current and sends it to the AD of the microcontroller for further processing. When exposed to light radiation, a photocurrent is formed inside the phototransistor and enters the emitter from the base, thereby obtaining an amplified signal current in the collector circuit. Compared with a photodiode, it has a large photocurrent amplification effect and therefore has a higher sensitivity.

2.2 MSP430 MCU module design

The system single-chip microcomputer module uses the MSP430F169 minimum system board. When working in charging mode, the AD sampling module is used to collect the output voltage value of the light signal detection module. According to the analysis of the collected voltage changes, a control signal is generated to control the rotation of the stepper motor to achieve the tracking and positioning of sunlight. When working in lighting mode, the single-chip microcomputer can use AD to collect the voltage value of the photoresistor, and generate control information to control the brightness of the lighting LED after data processing to achieve the automatic brightness adjustment function.

2.3 Motor control and drive module

The module mainly uses the control information generated by the microcontroller to rotate the solar panel to a certain angle to achieve the purpose of facing the sun. The motor drive circuit is implemented using the motor drive chip L298N. L298N is a constant voltage constant current bridge 2A driver chip produced by SGS. It contains a 4-channel logic drive circuit. The output voltage can be adjusted directly through the power supply, or the signal can be directly provided by the IO port of the microcontroller. The circuit is simple and easy to use.

2.4 LED lighting module

Since LED is current driven, the module should include a current source module when it is designed. When lighting at night, the module can convert the ambient brightness value detected by the photoresistor into a voltage change, and control the current flowing through the LED through data processing by the microcontroller module to achieve the function of automatically adjusting the LED brightness.

The input of this module is the output voltage of the MCU DA. After the input signal passes through the op amp and NPN, the C-pole current of the NPN is a constant current source. Therefore, it can drive the LED to achieve LED lighting.

3. System software design and analysis

The system software design mainly enables the microcontroller to realize data analysis and control circuit work through program design. The MSP430F169 microcontroller has a built-in 12-bit 8-external channel continuous approximation analog-to-digital conversion (AD) module and a 12-bit digital-to-analog conversion (DA) voltage output module. When the system is working, the microcontroller AD collects the detection voltage value of the phototransistor. After processing by the microcontroller, the DA converter converts the digital signal into an analog signal and adds it to the motor drive module to drive the motor to rotate so as to face the sunlight and charge with maximum efficiency. In addition, when the lighting is working, the light collection module converts the change in light signal intensity into a change in voltage, and inputs this voltage into the AD module of the MSP430 microcontroller to realize data collection. After the data is processed by the microcontroller, the DA module converts the digital signal into an analog signal and adds it to the LED lighting module. This method can automatically change the brightness of the LED according to the change in external light intensity.

4. Design feasibility analysis

The system consists of two parts: intelligent charging and LED lighting. When charging, the system can obtain the angle of sunlight based on detection and analysis, and control the rotation of the motor so that the solar panel faces the sunlight with the largest area, and can fully utilize the sunlight for charging. The intelligent LED lighting part uses a photoresistor to detect the brightness of the external environment, and then generates a control current to control the brightness of the LED through microcontroller analysis. The combination of these two parts can maximize the charging efficiency and automatically adjust the lighting brightness according to the ambient brightness, which can fully save energy and play a very important role in today's low-carbon life and energy conservation. In addition, the system is simple in design, low in cost, easy to operate, and has great feasibility.

5. Conclusion

The design of this system fully considers the current social theme of energy conservation, combines existing technologies and principles, and improves the charging lighting system. With the development of science and technology, the technology of efficient energy utilization will become more mature, and society will further strengthen energy conservation.