Research And Design Of A Wireless Humiture Measuring And Controlling System Of Granary Based On NRF905

Wireless sensor networks, is one of the three global high-tech industries,it is no less importance of Internet。It raises the remote sensing ability of the people with the real world,it has many features,such as low cost,low energy consumption,self-Organization and self-repairing.It will be widely used in military ,medical,industrial and so on.It is important for improving environmental monitoring.But,from current situation of development,wireless sensor networks has being in early stage of development many questions need to sovle,such as connecting the sensor node,price of sensor is not low ,functional consumption is great,self-organization and self-repairing is low.This system takes monitoring granary as background,and researches a wireless monitoring system which has simple using,long distance and fast speed transmission.The important question to research is how to update DS18B20,the paper puts a new method of software and harfware design.It has no longer need to modify software professionals when update DS18B20,but need to take new DS18B20 which written the same layer access the changing position,then,the system can automatic identification.so,it reduces greatly artificial maintenance costs,andconvenient non-technical staff operation.Due to the sensor node commonly used batteries,so reducing energy consumption is also a key research.First, System uses low energy consumption chip.Choosing the low power and AVR RISC 8-bit microcontrollers—Atmega16 as MCU ,this chip has six saving electricity mode through the software programming;Choosing NRF905 as the wireless transceiver,this chip can enter saving electricity mode through programming after sending and receiving ends,the current consumption is only 2.5μA in this mode.Second,in software programming,all of chip has in sleep mode when the system being in the out of work state,it can maximum reduce energy consumption.