Design of a Video Remote Control Car Based on STM32 Microcontroller

With the continuous advancement of science and technology, automation has become more sophisticated, and intelligent remote control systems are now being applied across multiple industries. The development of robotic cars is a key part of mobile robotics, integrating various technologies such as computer science, sensing, and communication. Its primary function is to use wireless network video technology to identify paths, control speed, and manage steering. This project uses an STM32 microcontroller as the main unit, enabling the transmission of live video via a Wi-Fi RF module (RT5350). The system involves a wide range of technical areas, including MCU programming, OpenWrt router configuration, and Windows-based software development. The implementation of this video-controlled car is divided into three layers: 1. **The underlying driver layer**: This layer is responsible for controlling the movement of the car’s motor and camera servo using the STM32 microcontroller. Since the STM32 cannot provide enough current to drive the motors directly, a motor driver module is used. In this case, the L298N module is employed to control the DC motors of the vehicle. 2. **The middle transport layer**: This layer handles the transmission of both control commands and video streams through the RT5350 router platform. 3. **The top-level control layer**: This layer allows users to control the car from a Windows-based interface. **1.1 Motor Drive Principle** The car is equipped with two motors on the left and right wheels. The direction of each motor determines the movement of the car. The STM32 microcontroller sends four control signals to the IN1–IN4 pins of the L298N, while the ENA and ENB pins are used for PWM speed control. The circuit diagram is shown in Figure 1.  **Figure 1: Circuit Schematic** The IN1 and IN2 lines control Motor A, which is connected to OUT1 and OUT2. Similarly, IN3 and IN4 control Motor B. Table 1 outlines the different motion modes based on the input signals. **Table 1: Corresponding Motion Modes of the Car**  **1.2 Motor Speed Control Principle** The L298N has two enable pins, ENA and ENB, which are active low. These pins must be pulled low for the motor to respond to the control signals. By adjusting the duty cycle of the PWM signal sent to ENA and ENB, the motor speed can be controlled. The principle behind this is that the motor receives power for a fraction of the time period T. The average voltage across the motor is calculated as U = V × t / T = aV, where a is the duty cycle (a = t / T). As the duty cycle increases, so does the motor's speed. Therefore, the rotational speed of the motor is directly proportional to the PWM signal's duty cycle.

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S/N	Project	General Parameter
1	Number of series	15S
2	Rated voltage	48V
3	End of discharge voltage	40V
4	Charging voltage	Recommend 51V (50.5V – 51.5V) for floating charge Recommend 54V (53.5V – 54.5V) for equation charge
5	Continuous charge and discharge curren	≤100A
6	Internal resistance (battery pack)	≤100mΩ
7	Self-discharge rate	≤2%/month
8	range of working temperature (≤95%R.H.)	0~65℃ charge -20~65℃ discharge
9	Storage temperature range(≤95%R.H.)	-40~70℃
10	Positive and negative lead way	Fence Terminal 2P*2
11	Display screen	LED display, four physical buttons
12	Protective function	Overcharge, over discharge, short circuit, overload, over temperature, etc.
13	certificate	MSDS,ISO9001,CE,UN38.3,ROSH

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