Music path-finding remote control car based on GD32

# Introduction

This is a smart car based on GD32. The car has functions such as music, tracking, navigation, Bluetooth, power display, etc. The specific introduction of these functions can be seen in the schematic diagram below.
When designing the PCB circuit, a size of 99*99mm was used.

# Function

1. Working status indication function
The car can have three working modes: remote control mode, tracking mode, and autonomous motion mode. These three modes can be switched and set by buttons, and the corresponding status indicator can display the current status.
2. Music playback function
The car can play music while running, and the music playback status can also be controlled by remote control. This is achieved through the music module. Since there is not enough space on the PCB, it is designed as a separate module.
2. Wireless remote control function
The remote control car can be used through wireless remote control. Design the corresponding Bluetooth control APP to control the car's movement direction, movement speed, headlights and music playback.
3. Automatic tracking function
The car has 5 tracking channels and can automatically track according to the black line. The specific situation also needs to be adjusted according to the black line.
5. The automatic obstacle avoidance function
uses ultrasonic waves to avoid obstacles. The car can retreat after encountering obstacles and continue to drive without obstacles.

# Module Introduction
## Main Controller

! [Main Controller] The main controller uses the Liangshan Development Board, which has GD32F470 on board.

## Power Supply

! [Power Supply] The power supply is controlled by a switch and is equipped with a power indicator.

## Speaker

! [Speaker] The speaker uses an active buzzer and is controlled by a pin. (After testing, this circuit does not work properly. See the "Errata and Instructions" below for details)

## Remote Control

! [Wireless Remote Control] The HC-05 Bluetooth module is used for remote control. The car is controlled through a mobile phone App.

## Ultrasonic Obstacle Avoidance

! [Ultrasonic Obstacle Avoidance] The HC-SR04 ultrasonic module is used to realize the distance measurement function of the car, and then the obstacle avoidance function of the car is realized.

## LED Light

! [Status Indicator Light] The car is equipped with two lights. At the same time, there are two status indicators for the buttons.

## Mode Control Button

! [Button] The car is equipped with two mode switching buttons. At the beginning, the car is initialized by default and the button is turned off. The next two buttons can be combined into Bluetooth remote control mode, tracking mode, and autonomous motion mode.

## Tracking

! [Tracking] The car is equipped with a five-way tracking module, which can track along the black line.

## Movement

! [Motor] The car is a four-wheel drive car. Considering the actual situation, the car bracket is not set, but the motor is directly loaded on the PCB. The motor uses an N20 motor, which is suitable for small PCBs and easy to install.

## Music module
The music module is implemented using a passive buzzer, a triode and a music IC. The music is controlled by the MCU. "To Alice" can be played during operation. Due to voltage reasons, the tone may be low when implemented.
The specific schematic diagram is attached at the end of the article.

# Errata and instructions
## Buzzer description
In the original video tutorial, PNP is used. In the actual circuit test, it was found that the buzzer module would ring as long as it was powered on, and it was not controlled by the pin. After discussion in the group, it is suspected that the buzzer pin must be set to a high level from the moment of power on to prevent it from ringing. If the pin is floating or waiting to output a low level, a loop is indirectly formed to pull the base down, and it will naturally ring. The normal solution is to just replace it with an NPN.
Since my PCB has been soldered and the components have been bought, I don't want to bother. So in the project implementation, I directly used a separate buzzer module to implement it.
## Flying line description
In the actual implementation, in order to complete the project, I had to use flying lines.
1. Battery holder flying line: This reason is stupid. I didn't pay attention when I bought the battery holder. As a result, I found that the positive and negative poles of the battery holder and the PCB were reversed after receiving the goods... There was no space at the bottom of the PCB... So I had to use flying lines.
2. Music module flying line: Because the size of the PCB designed at the beginning was 99*99mm, considering that there might not be enough space, and the PCB had been roughly designed at the time, it was not attached to the main board, but became a separate module.

![Flying line description]
## No other instructions
are available, if there are any, I will add them later.