With the development of technology, there are more and more applications based on distributed, wireless sensor networks. This paper presents an experimental platform for wireless sensor networks based on embedded systems. The experimental platform has good application prospects in the algorithm and protocol verification of wireless sensor networks.
The development of integrated circuits, microelectromechanical systems, and communication theories has prompted the emergence of wireless sensor networks. This wireless sensor network is composed of many self-powered sensor nodes. Each sensor node can collect surrounding data, perform simple calculations, and communicate with other nodes and the outside world. The multi-node nature of the sensor network allows numerous sensors to work together to perform high-quality sensing and to form a fault-tolerant acquisition system. Because of these advantages, many distributed wireless sensor network applications have emerged in recent years, such as rescue and disaster relief, smart home, and detection and rescue of biochemical weapon attacks. 
However, as an emerging technology, establishing a well-functioning and robust wireless sensor network still faces many challenges. And because of its unique characteristics, the design method of wireless sensor networks is very different from the existing wireless network design methods. For example, due to the dense distribution of sensor nodes in the sensor network, a wide range of data management and processing technologies are required. Secondly, wireless sensor network nodes are generally deployed in areas that are difficult for humans to reach and touch, which makes the maintenance of sensor network nodes facing great challenges. In addition, power consumption is also a very important issue. As a tiny device, wireless sensor nodes can only be equipped with a limited power supply. In some applications, it is almost impossible to replace the power supply. This makes the life of the sensor node largely dependent on the life of the battery, so reducing power consumption to extend the life of the system is the primary consideration for wireless sensor network design. Many researchers in wireless sensor networks are focusing on new power-saving protocols and algorithms. These protocols and algorithms require sensor network platforms for experimentation and verification. In this article, we will introduce a wireless sensor network platform to experiment and verify protocols and algorithms.
Wireless sensor network platform architecture
In general, a wireless sensor network includes sensor nodes and sensor network gateway nodes, as shown in Figure 1. The gateway node is used to combine data obtained from each sensor node and is responsible for communication with the outside world. The node is based on an embedded system.
The sensor node first collects environment-related data such as sound, light, and distance, and then simply processes the data and transmits it to the gateway node. Wireless sensor networks usually have two application modes: active polling mode and passive mode. The active mode requires the gateway node to actively poll each sensor node to obtain messages, while the passive mode requires the gateway node to respond in a timely manner when a certain sensor node event occurs. The data obtained by each sensor node can also be combined, which also greatly improves the efficiency of the sensor network. Of course, this also requires sensor nodes to have a certain amount of computing power.
System hardware implementation
In the system architecture introduced in this article, the hardware platforms of sensor nodes and gateways are mainly required. The hardware implementation of these two platforms is introduced below.
1. Hardware implementation of sensor node
The function of the sensor node is to collect the data that people are interested in and send the data to the gateway of each sensor node group. The sensor node is mainly composed of a power supply module, a computing module, a storage unit, a communication module, and a sensing unit, as shown in Figure 2. 
The function of the computing unit of the sensor node has been introduced in the previous section, and TI's 16-bit microcontroller MSP430F149 is used in our system. MSP430 has abundant on-chip storage resources. At an operating frequency of 5 MHz, the power consumption of MSP430 is about 1.5mW, and the microcontroller also has a variety of power-saving modes to choose from. In addition to abundant on-chip storage resources and multiple power-saving modes, the MSP430 also has multiple AD interfaces and I / O data lines, making it easy to program in software, and these interfaces can also be used as interfaces with sensor units.
The function of the communication module of the sensor node is realized by the nRF903 radio frequency transceiver. The low power consumption and small size of the transceiver make it very suitable for use in wireless sensor network systems. The transceiver can work in public frequency bands such as 433MHz, 868MHz, and 915MHz. The RF module communicates with the MSP430 through the serial port. nRF903 can also determine the transmission power according to the input current, this feature makes it have the following advantages:
a. One node can automatically adjust the number of adjacent nodes to communicate, so that the scale of the entire network can be adjusted.
b. A node can use less energy when communicating with relatively close nodes.
c. It can be used to assist in wireless channel collision detection.
d. It can be used to determine the relative position of a node in the network.
Each sensor node is powered by AA batteries.
2. Hardware implementation of the gateway
The hardware part of the gateway is mainly composed of the central processing unit, storage unit, RF transceiver module and GPRS communication module, as shown in Figure 3. 
The central processing unit of the gateway is mainly used to process the data collected from the sensor nodes and complete some control functions. The main device of the central processing unit is Atmel's AT91RM9200 microprocessor. AT91RM9200 is an ARM processor based on the ARM920T instruction set. The processor has a wealth of peripherals and interfaces, which enables it to complete some feature-rich applications at low cost and low power consumption. AT91RM9200 processor integrates many peripheral interfaces, including USB2.0 interface and Ethernet interface. In addition, the processor also provides multiple communication interfaces that comply with industry standards, including audio, telecommunications, flash memory cards, infrared, and smart card interfaces.
In order to transfer the collected data to the Internet, the gateway device is also equipped with a GPRS communication unit. The GPRS communication unit is mainly composed of the Sony-Ericsson GM47 module, which collects the data collected by the sensor through China Mobile's existing GPRS network. On the transmitted Internet, users can observe the data collected by the sensor through ordinary PC and GPRS mobile phone terminals. The gateway is also equipped with the same RF transceiver module as the sensor node, which is used to receive the data sent by the sensor node.
System software structure
In our wireless sensor network system, the software part is mainly on the gateway and sensor nodes. The main function of the software on the gateway side is to process and manage the data transmitted by the sensor nodes. It is mainly composed of GPRS communication software, RF communication software, command line software and task management software, as shown in Figure 4. 
Taking into account various needs, we use the open source operating system-Linux. Linux is a networked operating system environment, especially suitable for network applications. Linux has a complete TCP / IP protocol stack, at the same time? ? ? Supporting multiple other network protocols, such as the PPP protocol stack, makes it easy to implement GPRS dial-up functions. Due to the open source nature of Linux, users can easily develop their own applications based on it.
The software on the sensor node is mainly developed by assembly and C language. The main function is to accept the data of the sensor unit and send the data to the gateway of the sensor node group.
Summary of this article
This article introduces a wireless sensor network demonstration system for embedded systems. The entire system is built on the basis of embedded Linux and ARM processors. It has the advantages of low power consumption and easy software development.
With the increasing development of society and science and technology, wireless sensor networks will be increasingly widely used. At present, the wireless sensor network is still insufficient in terms of energy and node scale. With the resolution of these problems, the wireless sensor network will inevitably be more and more widely used in the fields of environmental monitoring, intelligent building and military.
Outdoor Rental Stage Event LED Display
This series is a professional outdoor waterproof rental LED display, IP65 waterproof level is not afraid of wind and rain and anti-corrosion function. It is used for professional large-scale concerts, concert stages, various party activities, evening parties, band performances, etc. Good quality guarant with 2 year warranty, professional good after-sale service.
As Professional Manufacturer of LED Screen, we fouce on quality and provide very good price and warranty service.
Outdoor Rental Stage Event LED Display,perfect well fit product for your indoor events solution, welcome to consult. Contact us to know more now!
Outdoor Rental Stage Event Led Display,Outdoor Concert Stage Background Wall,Outdoor Stage Rental Led Screen,Events Venue Led Screen System
Guangzhou Cheng Wen Photoelectric Technology Co., Ltd. , https://www.ledscreencw.com