【LiChuang Development Board】Smart car made of toothpicks

### ***I. Function introduction***


1. Tracking
2. Bluetooth remote control
3. PWM motor speed regulation
4. Car charging


### ***II. Hardware introduction***


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Lithium battery power supply: Use one 18650 3.7v battery for power supply, use PW5100 to boost to 5v, LED3 in the figure is used as power indicator. (It is recommended to modify it to two 18650 lithium batteries in series, and use the buck chip to reduce the voltage)

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Type-c charging: Use TP4056 battery charging management chip and type-c to charge the lithium battery. (Note that the pad of the type-c interface must be drawn larger, otherwise it will be difficult to solder. I learned this the hard way.)

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Bluetooth module: Use the Bluetooth module to control the car.

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Motor drive: Because the microcontroller i/o port driving capability is insufficient, I chose the L9110S motor driver chip. The L9110S motor driver chip has three output states: forward, reverse and high impedance. It can be used with pwm for speed regulation.

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Tracking circuit: The tracking circuit is designed with LM393 voltage comparator and ITR9909 infrared tube. ITR9909 has the functions of transmitting and receiving. The reflection of infrared light in different color sections is fed back to the microcontroller through the comparator.


### ***Three. Problems encountered and summary***


Problems encountered during the development process: The two motors on the circuit board are placed in reverse, there are some problems in the welding of the tracking circuit, which makes it unusable, and the spacing between the motherboards is too small.

Summary: This is the first time I have made a small smart car. With the help of the official, I finally completed the production of the car. Although the car still has many defects, it is full of gains. In the process of making the car, I learned to write code and draw circuit boards, and learned to find and solve problems by myself. Here, I would like to thank the official LiChuang for hosting this event and thank you for your help in the QQ group.