2015 National Undergraduate Electronic Design Competition H based on CW32

Topic Requirements Topic
Analysis
1.1 Topic Analysis
This topic is a boost circuit with an input of 3-3.6V, which requires the current to be controllable, and can be instantly shut down and over-voltage alarm. The National College Student Electronic Design Competition has this kind of current controllable topic over the years. Here, our simplest method is to use LED constant current chips. Of course, we can also use BOOST chips directly, and connect the FB voltage feedback pin of boost to our microcontroller through op amps and other conditioning circuits to achieve current adjustment. However, one advantage of using LED constant current chips is that only a PWM signal needs to be input, and the peripheral circuit is simple, saving a lot of work.
 
1.2 System Framework The
figure above shows the main framework of this system.
The first input is a voltage of 3 to 3.6V, but our microcontroller is an input of 3.3-5V, so we need to design a boost auxiliary circuit to power the microcontroller, and at the same time, we need to press buttons and OLED screens to know the current running state of our system. In the latter stage, we need to design an op amp amplification circuit to collect current for the microcontroller to achieve a closed loop, and then the microcontroller controls the constant current chip to make the current stable.
 
Schematic Design Description
2.1 CW32 MCU
CW master control uses CW32F030C8T6 minimum system development board, with the highest main frequency of 64MHz, 64K bytes FLASH, data retention for 25 years, 8K bytes RAM, support parity 128 bytes OTP memory, five-channel DMA controller, completely surpassing STM32, and has a wide range of applications in aerospace and national defense military, with
super high cost performance, and you can apply for a development board for free. 2021 is the 20th anniversary of the establishment of CW, and it is also the year for Xinyuan Semiconductor to accelerate high-quality development. It is also a major turning point in the transformation of listed companies from agency distribution to a dual-core strategy of chip design and agency distribution. In the future, the company will continue to move forward steadily, specialize and strengthen in the field of chip research and development, and actively respond to and implement the country's great strategy of domestic substitution in the chip industry.
CW32 Ecological Community:
WeChat public account search: "CW32 Ecological Community" --> Click to follow, you can apply for development boards and chips for free. Dear friends, use your creativity and imagination, work together to promote the development and development of CW32! ! !
 
2.2 Auxiliary power supply
The auxiliary power supply uses MT3608, which is a highly efficient boost chip with a simple peripheral circuit. The output voltage is configured by a voltage divider resistor. Here we must pay attention to the input need to connect a ceramic capacitor close to the input pin of the chip, otherwise the chip is easy to burn out when powered on.
2.3 Main power circuit
The figure above is the main power circuit, which is mainly composed of SY7200AABC constant current chip, Q1mos tube controls the current on and off, P3 is the interface for connecting the ammeter, P2 is connected to the output, and the voltage signal is sampled by R18 and R19 to the microcontroller. The voltage ratio is 20/20+100*OUTPUTVOLTEG. The current signal is amplified by the differential amplifier circuit composed of LMV321 to the ADC pin of the microcontroller. The amplification factor is 20 times. When the current is 1A, the R11 sampling resistor is 0.2V, and the amplification factor is 4V. 2.4 Input and
output circuit
The input and output circuit consists of buttons and OLED, and OLED is IIC communication.
 
PCB design description
On the front of the PCB, when wiring, we must make the power line thick enough, and at the same time, the sampling line should avoid high-frequency devices, increase the vias and ground, so that the signal is not easily interfered by the outside world.
 
Software description
The important part of the program is PWM output. The performance of CW32 is very strong. For this type of PWM duty cycle, it can be accurately controlled, and multi-task operation is completely stress-free.

Physical display instructions
 
 
Demonstration video
https://www.bilibili.com/video/BV1zV4y1h7fP/?vd_source=2115628cb2ad4920fc2783689dd43b85
Due to the strong light of LED, in order to protect the eyes, we use sliding rheostat to replace LED.
Other attachment upload
tips: The works participating in the event must upload the project-related program attachments to the open source platform or personal code storage cloud. The maximum upload size of the attachment is 50M (please do not upload in the LiChuang workspace, there are restrictions)