[Lichuang Classroom] Temperature and humidity alarm based on 51 microcontroller

1. Function description:

• This design is a temperature and humidity alarm system based on STC89C51/52 microcontroller;
• It is equipped with four independent buttons, whose functions are set, add, subtract and confirm respectively, which can realize the adjustment of alarm threshold;
• This design uses AT24C02 memory chip, which can still save the set alarm threshold in the event of power outage;
• This design uses LCD1602 liquid crystal display. The upper row displays the current temperature and humidity, and the lower row displays the corresponding cold, hot, dry, and wet conditions;
• The fully digital temperature and humidity sensor DHT11 is selected, which has a wide temperature measurement range and can meet general needs;
• When the temperature or humidity exceeds the threshold range, there will be a buzzer alarm prompt and the corresponding LED alarm light will light up;

2. Design features:

• PCB board size is 8.2cm×10cm, and can be sampled at Jialichuang;
• Except for the power supply socket, all other components use direct plug-in devices to facilitate welding;
• Powered by microUSB.

3. Accessories

• The program in the attachment, C file and Hex file, is not well written (very bad kind of bad, can only be said to be usable);
• The program is for reference only, everyone is welcome to optimize it.

4. Video demonstration:

• Link to Station B: https://www.bilibili.com/video/BV1ci4y1472F
• The following is a video preview. For high-definition videos, please visit the B station link above. Remember to watch it three times~