smart car

A smart car designed based on the Liangshan School development board. The functions are shown in Figure 1.1. It realizes 8-channel PWM control of the four-wheel motor of the smart car (including speed regulation and forward and reverse rotation of each motor), Bluetooth control (including APP_inventer writing Mobile phone APP), OLED display, LED lights, buttons, ultrasonic and tracking and other basic functions programming.
![image.png]                                                                                                                                              **Figure 1.1 Function Overview**
Among them, the pits I discovered during the debugging process include:
①Buzzer drive circuit:
Before the change, as shown in Figure 1.2, the GD32F470 was not considered The output level of the I/O port is 3.3V, so in the actual circuit debugging, no matter whether the output is high level or low level, the base voltage of the PNP transistor is always less than the emitter voltage, so the transistor is always in the on state, so that The buzzer kept ringing differently after connecting to the Liangshan Sect. After the modification, as shown in Figure 1.3, the I/O port of the Liangshan School can control the buzzer on and off normally.
![image.png]                                                      Figure 1.2 Before modification
  ![image.png]                                                      Figure 1.3 After modification

② Selection of anti-reverse connection diode: I don’t know whether this is a quality problem of the buck chip or a problem of diode on-resistance, it is just under testing It was found that after connecting the diode, the Liangshan School always automatically resets when the motor is started, but it works normally after removing the diode. Therefore, I hope everyone will take my case as a warning and carefully consider the parameter selection of these two. The diode I chose is SS14 40V1A Schottky diode, and the buck chip is MD5350 (1.2~7V input, 5V1MA output) (because I happened to have this chip on hand, I did not purchase the chip used in the official case. The chip was slightly hot during the test) , but it can be used, hahaha).
③ For the tracking module, the labels of the two detection heads on the far right were copied without changing the labels. As a result, no matter whether the infrared tracking module is covered or released during debugging, normal detection is never possible. Therefore, the connecting wires of the two modules were scraped off the circuit board, so that every test returned to normal.

The program written can refer to the attached smart car program. The framework is shown in Figure 1.4.
~~![image.png]                                                                                                                               ** Figure 1.4 Program display**
Bluetooth control, tracking and ultrasonic video verification: [Smart car physical verification](https://www.bilibili.com/video/BV1VN411D7HT/?spm_id_from= 333.999.0.0&vd_source=01c9fdc6ffc893b061cb21f1e3167eba)
For details on low battery alarm verification and screen display verification, see the attached video.