Environmental monitoring based on 51 microcontroller

Project Overview:
This project uses the STC89C52RC as the main control MCU to create an environmental monitoring circuit, realizing the monitoring of changes in temperature, humidity, light intensity, and smoke concentration. It also adds an LCD1602 interface and a DS1302 clock module interface, displaying the collected data on the LCD1602 and showing the time. The baseboard has two reserved 5V relay interfaces for further customization. This project adopts a design that separates the baseboard from the MCU core board, increasing circuit reusability and modular design for higher circuit reuse.
The minimum system board uses Type-C power supply and is equipped with a CH340C, enabling direct Type-C programming. The minimum system board uses pin headers and jumpers to isolate the MCU power supply; removing these disconnects powers off the MCU, allowing the 51 microcontroller to be programmed.
The baseboard uses a DC005 interface for 5V power supply, controlled by a DIP switch. The minimum system board is equipped with an AMS1117-3.3V converter to 5V, and provides three 5V and 3.3V outputs to the baseboard for future development. It is recommended to use capacitors of 220uF or higher for energy storage to prevent system malfunctions due to unstable power supply.
Two 5V relay interfaces are provided. PCB design files for the relays and DS1302 are included in the project for reference only.
The schematic and PCB designs
comply with JLCPCB's free prototyping policy and are available for free prototyping.
The baseboard uses a two-layer layout. Considering the overall layout, the interfaces are placed on the outside, and the buttons are placed on the bottom. Power lines use 30mil, and signal lines use 15mil.
3D rendering and physical prototype
are shown.