Research Article International Journal of Distributed Sensor Networks 2017, Vol. 13(2) A reconfigurable smart interface based Ó The Author(s) 2017 DOI: 10.1177/1550147717693848 on IEEE 1451 and field programmable journals.sagepub.com/home/ijdsn gate array for multiple Internet of Things devices Shulong Wang1,2, Yibin Hou1,2,FangGao1,2 and Xinrong Ji1,2 Abstract The Internet of Things is becoming increasingly important in traffic, medical treatment, and other industry fields. With the development of the Internet of Things technology, lots of new ‘‘things’’ need to be accessed to the Internet of Things. Currently, Internet of Things applications adopt multiple methods to access the heterogeneous devices. How to provide unified access means for those ‘‘things’’ is a fundamental issue. To solve this problem, a new method is proposed in this article to design a reconfigurable smart interface for multiple Internet of Things devices. The IEEE 1451 standard is adopted for this design, and it comprehensively specifies the smart transducer design and relevant interface protocol to implement the intelligent acquisition for common sensors and actuators. Field programmable gate array is adopted for the implementation of this design to reduce consumption of resources and enable the reconfiguration of the whole system. Performance of the proposed system is evaluated, and good performance is achieved in practical application for office environment monitoring. Keywords Internet of Things, IEEE 1451, field programmable gate array, sensor, actuator Date received: 20 July 2016; accepted: 17 January 2017 Academic Editor: Jayavardhana Gubbi Introduction intelligent identification, positioning, tracking, moni- toring, and management.1,2 The Internet of Things (IoT) was first proposed to IoT is a major drive to support service composition study radio frequency identification (RFID) by with various applications.3 The architecture of IoT is Ashton, Professor of the MIT Auto-ID Center in 1999. illustrated in Figure 1. It consists of three layers: With the technological development, the concept is constantly updated. The well-established concept was proposed by the International Telecommunication 1Beijing Advanced Innovation Center for Future Internet Technology, Union on the ITU Internet Report, which was given as Beijing University of Technology, Beijing, China two-dimensional code reading equipment, RFID 2Beijing Engineering Research Center for IoT Software and Systems, devices, infrared sensors, global positioning system Beijing University of Technology, Beijing, China (GPS), and laser scanners, and other information sen- sing device, according to the agreed protocol, connect Corresponding author: Yibin Hou, Beijing Advanced Innovation Center for Future Internet to any object under the Internet for information Technology, Beijing University of Technology, Beijing 100124, China. exchange and communication, in order to achieve Email: [email protected] Creative Commons CC-BY: This article is distributed under the terms of the Creative Commons Attribution 3.0 License (http://www.creativecommons.org/licenses/by/3.0/) which permits any use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (http://www.uk.sagepub.com/aboutus/ openaccess.htm). 2 International Journal of Distributed Sensor Networks Figure 1. Architecture of IoT. perception layer, network layer, and application layer. cameras. According to the transmission rate, these con- For the perception layer, various sensors, actuators, nected devices are classified into low-speed and high- RFID tags, and other ‘‘things’’ are connected to the speed equipment. Typically, kinds of sensors, actuators, IoT with specific interfaces.4 Network layer is responsi- and RTC belong to the low-speed equipment, while ble to establish the communication between ‘‘things’’ hard disk and camera belong to the high-speed and humans. Currently, Ethernet and wireless local equipment. area networks (WLAN) are widely used in different To address the heterogeneity problem of device application environments of IoT, and some new com- interfaces, there are a lot of systems and interface munication technologies such as narrow band Internet equipment available on the market.6–8 However, most of Things (NB-IoT) are becoming more and more pop- of them work in a specialized environment and access ular. For application layer, various applications and limited number of devices with specialized interfaces. business functions are realized for different purposes, Furthermore, the systems or interface equipment could such as intelligent transportation, green agriculture, not be reconfigured or reused for other applications, and wise medical and smart home. which result in a serious waste of resources. To deal Compared with the Internet which has realized the with this problem and provide a unified interface, the communication between computers and smart devices, Institute of Electrical and Electronic Engineers (IEEE) IoT mainly enables the ‘‘things’’ to talk to each other. has launched IEEE 1451 Smart Transducer Interface Those ‘‘things’’ work as the antenna of the IoT huge Standards protocol. This protocol defines a series of system and form the foundation of the various intelli- specifications from sensor and actuator interface defini- gent applications.5 How to realize the unified access to tion to data acquisition, and it not only allows for the the IoT for various ‘‘things’’ is a fundamental and key development of smart sensors and actuators but also issue. leads to uniform industrial standards.9 Kumar and With the rapid development of IoT technology, a Hancke10 have presented a low-cost and energy- large number of devices and equipment join the differ- efficient prototype of a smart comfort sensing (SCS) ent application areas of IoT: intelligent transportation, system–based IEEE 1451 for the real-time monitoring green agriculture, wise medical, smart home, and so on. of thermal and air quality comforts in situ. Song and Among these devices, different interfaces are adopted Lee11 have proposed a smart transducer web services between each other. As shown in Figure 2, the univer- (STWS) prototype system based on IEEE 1451, and sal asynchronous receiver transmitter (UART), general standardized way for sensor applications to access and purpose input output (GPIO), and other point-to-point interoperate with IEEE 1451 smart transducers was dis- interfaces are usually adopted by sensors and actuators. cussed in detail. However, the devices with this protocol The controller area network (CAN), inter-integrated are still not widely deployed in real IoT environment.12 circuit (IIC), universal serial bus (USB), and other bus For these existing works, most of them could only interfaces are the common interfaces of on-board units access limited types of sensors and actuators for specific (OBU), real-time clock (RTC), and hard disk. ZigBee, domains. The main reason lies in the high resource cost Ethernet, and other kinds of net interfaces are usually and complexity for adopting the protocol. Typically, it used to connect wireless sensor nodes and digital needs to deploy two physical processors to handle the Wang et al. 3 GPS URAT Sensors Point-to-point Actuators GPIO Low-speed RFID Other OBU CAN Interfaces Devices RTC IIC Bus Hard Disk USB Bluetooth Bluetooth High-speed Modules Wireless Zig Bee Sensor Nodes Net Cameras Ethernet Figure 2. Devices and interfaces in IoT. whole system, while the present system usually only Analysis of IEEE 1451 and FPGA takes one. In addition, the protocol focuses on those In this section, the key technologies applied in the pro- low-speed devices in IoT such as sensors, actuators, posed design are analyzed and summarized in detail. and transducers, while ignoring other high-speed devices or equipment. To solve the above problem, field programmable IEEE 1451 standard gate array (FPGA) seems to be a good solution. First, compared with the micro control unit (MCU), FPGA To solve the problem that the current sensor bus inter- can be configured to be multi-core processors and faces are not compatible with each other, the IEEE deployed to process different modules in the whole sys- launched the IEEE 1451 standard to provide unified tem. Besides, FPGA can support various low-speed and sensor interfaces. The family of this standard defines a high-speed interfaces through custom-designed intellec- set of common communication interfaces to connect tual property (IP) core. With the characteristics of smart transducers to microprocessor-based systems, re-programmability, the system implemented by FPGA instruments, and networks in a network-independent can be reused and extended for other applications. environment. The main objectives of this standard are By focusing on these issues, this article designs and as follows: implements a reconfigurable smart interface for multi- ple IoT devices. This design adopts FPGA to imple- To enable plug and play at the transducer (sen- ment the whole system with re-programmability. With sor or actuator) level by providing a common IEEE 1451 standard, the design can support various communication interface for transducers; transducers for data acquisition and control. By taking To enable and simplify the creation of networked full advantage of IP core, this design can also support smart transducers; other devices in IoT. With this design, the system could To facilitate the support of