[Lichuang Development Board] Smart car based on Liangshan School

#Liangshanpai development board smart car design
## 1. Circuit design
### 1. The
main control unit is designed using the Liangshanpai development board as the control unit. The Lichuang·Liangshanpai core board is as shown in the figure.
![image.png] ### 2. Power supply circuit design
![image.png] The power supply is connected to the lithium battery through the battery holder P3 and then supplies power to the car. After the 7.4V power supply comes in, it is stepped down by the buck chip to obtain a 5V voltage to power the development board. D1 is a Schottky diode, which prevents the positive and negative poles of the power input terminal from being reversed and serves as a protection circuit. LED1 is the power working indicator light. When the power switch SW1 is turned on, the system turns on the power supply and LED1 will be lit. C1 and C2 are 100uF capacitors, which mainly serve as buffers.
### 3. Motor drive circuit For
the motor drive module, I chose the L9110SM/TR chip to drive the motor and control the rotation and speed of the wheel. The circuit is as follows.
![image.png] ![image.png] ### 4. Tracking circuit
The design of the tracking circuit takes advantage of the principle that infrared light has different reflection levels when encountering different colors of ground. The tracking circuit is designed using the LM393 voltage comparator and the ITR9909 infrared pair tube. The tracking circuit design schematic is as shown in the figure.
![image.png] ### 5. Obstacle avoidance circuit
The obstacle avoidance circuit uses the ultrasonic HC-SR04 module, as shown in the actual picture and the car interface circuit.
![image.png] ![image.png] ### 6. Button circuit
mode button to select the mode, press the start button to start, the circuit schematic is as shown in the figure.
![image.png] ### 7.LED circuit
The schematic diagram of the LED light circuit is shown in the figure.
![image.png] ### 8. Bluetooth module
This circuit uses the WL9981TC Bluetooth transparent transmission module, as shown in the actual picture.
![image.png] For the convenience of use, it is designed as a pin header module circuit diagram with an interface of 6*2.54mm, as shown in the figure.
![image.png] ![image.png] ## 2. Mobile APP design
Based on the mobile phone Bluetooth smart car control APP designed by MIT APP Inventor, the APP interface design is as shown in the figure.
![qq_pic_merged_1676037299084.jpg] ## Physical display
![QQ picture 20230210192020.jpg]