车内滞留儿童远程报警系统设计
摘要
本设计提出一种基于 STC89C52 单片机的车内滞留儿童远程报警系统。系统核心功能包括：通过 HX711 传感器检测驾驶员是否离车，为后续监测触发提供判断依据；借助 D203S 人体热释电传感器监测车内是否有儿童滞留，在检测到驾驶员离开且车内有人时自动启动环境监测模式。通过 SGP30 传感器实时监测车内 CO₂浓度，当检测到儿童滞留且 CO₂浓度超过安全阈值时，立即触发声光报警模块发出警示，同时通过 ULN2003A 驱动步进电机自动打开车门，并由 4G 模块向预设手机号发送报警短信；通过 DS18B20 温度传感器采集车内温度，若儿童滞留且温度超出安全范围（过高或过低），同样触发声光报警、车门自动开启及 4G 短信报警。当 CO₂浓度与温度同时异常时，系统同步执行多重响应措施。LCD1602 显示屏实时展示车内温度、CO₂浓度、人员状态及设备工作信息，用户可通过按键切换至阈值设置界面调整安全参数，或手动控制车门开关状态。
该系统的作用在于构建 “人员检测 - 环境监测 - 多维度响应” 的安全防护体系。通过精准的人员存在判断与环境参数监测，实现危险的早期识别；声光报警模块在车内形成直接警示，4G 模块则突破空间限制实现远程预警，步进电机驱动车门开启为儿童提供逃生通道。为车内滞留儿童提供了主动防护与快速救援的技术保障，有效降低安全事故发生率，为家长和监护人提供可靠的安全辅助，守护儿童乘车安全。
关键词：STC89C52；车内滞留；远程报警；环境监测；声光报警；4G 通信
Design of Remote Alarm System for Children Trapped in Cars
Abstract
In the current era of widespread popularity of automobiles, safety accidents caused by children being stranded in cars are frequent, and sudden temperature changes and elevated CO ₂ concentrations in enclosed environments pose a serious threat to children's life safety. Due to the weak self rescue ability of children, the traditional reliance on manual inspection can easily lead to tragedies due to negligence. Therefore, the development of a remote alarm system that can monitor the status of passengers and environmental parameters in real-time and automatically respond in case of danger is of great practical significance.
This design proposes a remote alarm system for children stranded in a car based on STC89C52 microcontroller. The core functions of the system include: detecting whether the driver has left the vehicle through the HX711 sensor, providing a judgment basis for subsequent monitoring triggers; By using the D203S human body pyroelectric sensor to monitor whether there are children stuck in the car, the environmental monitoring mode will be automatically activated when the driver leaves and there are people in the car. Real time monitoring of CO ₂ concentration inside the vehicle through SGP30 sensor. When a child is detected to be stranded and the CO ₂ concentration exceeds the safety threshold, the sound and light alarm module is immediately triggered to issue a warning. At the same time, the ULN2003A drives the stepper motor to automatically open the car door, and the 4G module sends an alarm message to the preset mobile phone number; Collecting the temperature inside the car through the DS18B20 temperature sensor, if a child is stranded and the temperature exceeds the safe range (too high or too low), it will also trigger an audible and visual alarm, automatic door opening, and 4G SMS alarm. When the concentration of CO ₂ and temperature are both abnormal, the system synchronously executes multiple response measures. The LCD1602 display screen displays real-time information on the temperature inside the car, CO ₂ concentration, personnel status, and equipment operation. Users can switch to the threshold setting interface by pressing buttons to adjust safety parameters, or manually control the door switch status.
The function of this system is to build a security protection system of "personnel detection environment monitoring multi-dimensional response". By accurately assessing personnel presence and monitoring environmental parameters, early identification of hazards can be achieved; The sound and light alarm module forms a direct warning inside the car, while the 4G module breaks through space limitations to achieve remote warning. The stepper motor drives the door to open, providing an escape route for children. Provided active protection and rapid rescue technical support for children stranded in vehicles, effectively reducing the incidence of safety accidents, providing reliable safety assistance for parents and guardians, and safeguarding the safety of children while riding.
Keywords：STC89C52; Stuck in the car; Remote alarm; Environmental monitoring; Sound and light alarm; 4G communication
目 录
1 绪论
1.1 研究背景及意义
1.2 国内外研究现状
1.3 主要内容
2 系统总体方案设计
2.1系统总体设计
2.2 主要模块方案选择
3系统硬件设计
3.1 总体硬件框架
3.2 主控模块电路设计
3.3 驾驶员检测模块电路设计
3.4 儿童滞留检测模块电路设计
3.5 环境监测模块电路设计
3.6 显示模块电路设计
3.7 按键模块电路设计
3.8 声光报警模块电路设计
3.9 车门控制模块电路设计
3.10 4G 通信模块电路设计
4 系统程序设计
4.1 编程软件介绍
4.2 系统主流程设计
4.3 独立按键
4.4 LCD1602液晶显示子流程
4.5 称重模块子流程设计
4.6 SGP30模块子流程设计
4.7 温度检测模块子流程设计
4.8 步进电机子流程设计
5实物制作与功能测试
5.1 实物制作
5.2 人员检测与显示功能测试
5.3 环境监测与车门控制功能测试
5.4 声光报警功能测试
5.5 4G 远程报警功能测试
5.6 按键设置与阈值调整功能测试
6 总结
参考文献
致谢
附录A 原理图
附录B PCB
附录C 主程序
