第1个回答 2008-06-22
Today, the amount of greenhouse growing, the growing popularity of technology, how the temperature of the greenhouse better control became the key. Currently used in the greenhouse temperature detection systems are used by the analog temperature sensors, multi-channel analog switches, A / D converter and SCM, and other components of the transmission system. This temperature acquisition system needs in the greenhouse temperature within the layout of the large number of cables, can the signal sent to the scene of the sensor on the card acquisition, installation and removal of complex, high cost. At the same time line on the analog signal is transmitted, vulnerable to interference and loss, measurement errors are relatively large, are not conducive to control the temperature based on changes in a timely decision.
Based on this subject by a microcontroller and a digital single-bus technology temperature measurement and control system used in the design of the greenhouse programme, which is the use of temperature sensors will be greenhouse temperature change, transform into a current of change, then Enter into a voltage change in ADC, the value handled by the SCM, the last from SCM to control digital displays showing the actual greenhouse temperature. Once the temperature exceeded our pre-determined, the minimum level, SCM will activate alarm system for alarm as well as on the greenhouse temperature control.
The design of the programme is based on AT89C2051 microcontroller as the core, a smart temperature sensors DS18B20 the greenhouse temperature within the regular collection, measurement results can not only locally, but also can use the microcontroller serial port, through the RS-485 Communication lines and the data collected will be sent to the computer, further filing, processing. The monitoring system does not require any fixed network support, installation simple, stable and reliable system, maintainability good.