Design And Application Of Point To Point Bidirectional Communication In Wireless Sensor Networks

With the rapid development of the Internet of things,electronic communications and automatic control,Wireless Sensor Network(WSN)has gradually become an important research field in communication.WSN is widely used in military investigation,environmental quality monitoring,smart home and so on.Wireless communication is one of the key issues in sensor network.A point to point bidirectional communication mode is designed and verified in an example of temperature monitoring.The detailed research work and results are summaried as follows:The hardware platform of wireless sensor node is constructed and bidirectional communication mode is designed.The performance of common wireless communication is analyzed.NRF24L01 module is considered as the wireless transceiver following the comparision of communication distance and data transmission rate.The hardware platform of wireless sensor node is built by wireless transceiver NRF24L01 and ARM microprocessor.It mainly includes serial port transmission unit,analog to digital conversion unit and energy supply unit.The serial port transmission unit adopts CH340 G chip,which can realize the uploading of node data to computer.The analog to digital conversion unit uses the mode of direct memory access.This method stores the collected data information directly into the register and does not need CPU to process,heightening the efficiency of the microprocessor.The node energy supply unit includes switching mode power supply and Mini USB power supply.So the node can be adapted to a variety of power supply equipment.The design of bidirectional communication mode for wireless sensor nodes need to configure the NRF24L01 related registers.Then the receiving function and transmitting function are designed.The bidirectional communication is completed by configuring the working mode of each time slot in the nodes.The measured IRQ waveform matches the bidirectional communication IRQ waveform and has periodic characteristics.It means bidirecitonal communication is established successfully and works stably.The communication distance of designed node is 52 m in the curved corridor and 310 m in the outdoor,sunny and open environment,which completes a long distance communication.The bidirectional communication mode designed is applied to the temperature monitoring.The PT100 temperature sensor is used to insert one end into the copper heater.The other end is connected to the microprocessor through the bridge circuit and the signal amplifying circuit.The temperature acquisition node can control the heater to 100? by the relay circuit.It could send the actual temperature value to the temperature control node.The computer can realize the monitoring of node data using two main methods,including serial monitoring data and MATLAB dynamic curve monitoring.The example shows that wireless sensor network point to point bidirectional communication is designed successfully.