"基于AT89C51单片机的高精度湿度测控系统设计与实现"

The graduation project is a humidity control system centered around the AT89C51 microcontroller and HS1101 humidity sensor. The system is capable of real-time humidity detection and display, as well as control. The hardware circuit includes the AT89C51 microcontroller minimum system, humidity measurement circuit, clock circuit, digital display circuit, keyboard processing circuit, and control circuit. The project selected the high-precision HS1101 capacitive humidity sensor, which changes its capacitance in response to environmental humidity changes. The capacitance changes are converted into corresponding frequency changes through a conversion circuit, and the frequency is then sent to the microcontroller after being filtered through an optocoupler circuit to eliminate noise. The microcontroller calculates the signal and determines the humidity value through a lookup table, which is then displayed through the microcontroller's external interface circuit. The system allows users to set the desired humidity value through the keyboard, and the central control system compares the set value with the detected value. If the detected value is lower than the set value, the control system activates a relay to humidify the environment. Compared to traditional testing methods, this humidity control system offers advantages such as high reliability, accuracy, and cost-effectiveness. It is suitable for automatic humidity measurement and control, ensuring optimal operation of equipment and systems for efficient and comfortable production and living environments. Keywords: microcontroller; humidity; automatic control; HS1101.