With the modern industrial production and electronic technology becoming closer than ever before, temperature measuring and humidity measuring have been widely used in many industry applications. Monitoring temperature and humidity can help to ensure the safety of work house, enhance labor efficiency and also has a great practical value in improving the producing environment. Monitoring system for the Greenhouse storage, environmental conditions of the temperature and humidity is important. The design was mainly for the measuring of temperature and humidity inside the Greenhouse. DHT90 was chosen as a temperature and humidity sensor. After series of internal signal processing and analog-to-digital conversion, digital DATA were sent into AT89C52 single-chip microcomputer for the calculation and finally displayed on a monitor. This study analyzed the operational principle of DHT90, design the perfect system for measuring temperature and humidity in real-time. Took Proteus 7 Professional as a tool to design hardware, and utilized Keil uVision2 Version to design the software in the form of C language. When the design has been accomplished, system was able to perform stably and output reliable DATA, and had some extra functions like voice &LED alarm and time display.
Keywords Temperature measuring;Humidity measuring;predefined warning gate;time display