Design of Online Embedded Web Server for Data Acquisition System # Author

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1 Design of Online Embedded Web Server for Data Acquisition System # Author A.Shilpa #1 Dept. of ECE, Sreenidhi Institute of Science and Technology, AP, India Abstract this paper realizes an Embedded based Data acquisition and Control System that helps the user to monitor and control the data with a standard web browser. User will be monitoring the data collected by the sensors like temperature, light intensity, smoke and can remotely control the same. It consists of application program written in Embedded C in Keil Integrated Development Environments for accessing data through the serial port and updating on the server and on the web page simultaneously. Keywords ARM, TCP/IP, Web server I. INTRODUCTION Embedded Technology is an emerging field day by day with a lot of possibilities. Web access functionality is incorporated in a device that enables costeffective and widely accessible and user interface functions for the device. An ARM based web server unit in the system provides access to the user interface functions for the device through a device HTMl web page. A web server provides access to the end devices for the client by uploading web pages as per the client request. It is the central functional unit that hosts web pages thereby provides services as per client request. When the configured IP address is entered in the web browser, the predesigned HTML web pages gets displayed through which we can remotely monitor and control the sensor and device status respectively. The heart of communication is TCP/IP protocol. Network communication is performed by the IEEE Ethernet standard. It is the most modern technology of embedded systems that has brought Ethernet access to the same. An ARM based web server can be incoroparated into any of the appliance and connected to the Internet so that appliance can be monitored from remote areas through the web browser in a desktop system. Web server hosts a web site and provides reliable services for any requesting client. Any general purpose web server is composed of some kind of operating system, fast processor, special purpose hardware, large amount of memory, running applications and few web pages [5] etc. Such web servers are developed using general purpose computers. They use different kind of operating systems such as NT, Unix, Linux Windows etc. Fig1.Different Devices Connected For Automation Such systems apply typical client-server architecture where, the client accesses the server through the LAN router and the Internet. Client sends the request to the server. This request is processed by the router that connects the Internet. The web activities makes the request and finally connects to the desired web server system. Requested data is sent to the client. An embedded web server is a microcontroller including software andapplication code to monitor and control the systems. Microcontroller or ARM processor is an integral part of an embedded network and create a way for easy controlled activities of any device from any remote location. Such servers designed using very low resource usage, are highly reliable, portable and secure systems. II. SYSTEM HARDWARE DESIGN The system consists of three different parts. First is the Embedded Web Server. ISSN: Page 3266

2 CLIENT1 CLIENT2 CLIENT N EMBEDD ED WEB SERVER LPC 2148(ARM PROCESS OR) 10/100 ETHER NET MODU LE INT ER NE T In sending a frame a controller receives the message to send and the destination address from higher-level software. It calculates the Ethernet frame check sequence and places data, addresses and other information in the frames field. Half duplex interface Detects collisions, cancels any transmitted frame with a collision and tries according to protocol standard IEEE 802.3; in full duplex Ethernet segment doesn t need to support collision detecting because there are no collisions to detect and provides an indication of success or failure of a transmission. In receiving a frame a controller detects and synchronizes to new received frames. It ignores any frame that is less than the minimum size, ignores any frames that do not contain the interface s address or a valid multicast or broadcast address in the Destination Address field. It calculates the frame check sequence value, compares the result with the received value and indicates the errors if they don t match. B. RF module unit (Serial Communications) TARANG wireless modules based on Free scale MC1321X SIP, are low to medium power devices. They are suitable for adding wireless capability to any product with serial data interface. The modules require minimal power and provide reliable delivery of data between devices. The I/O interface provided with the modules help to directly fit into many industrial applications. The modules operate within the ISM 2.4 GHz frequency band with IEEE baseband. Fig 2 Architecture model Second is the user part or client and third one is the sensors and appliances to be monitored. The client thus monitors various parameter statuses through sensors and also controls many industrial appliances with the help of the web server. A. LPC 2148 Processor This is a 32-bit ARM7-TDMI-S microcontroller with 32kB of on-chip static RAM and 512 KB of on-chip flash memory. It has 128-bit wide interface/accelerator that enables 60MHz of operation. Also has In-System Programming using on-chip boot loader software, 400ms of full chip erase and 256 B of programming in 1ms. For interfacing of sensors, it has 10-bit ADC with 8 analog inputs and a conversion time as low as 2.44µs per channel. CPU operating voltage is 3V to 3.6V so that the proposed system requires only lower power consumption as the same mentioned before. The Architecture is based on RISC principles and its simplicity yields in a high instruction throughput and real-time interrupt response form a small and cost effective processor core. It also has another architectural strategy such as 16-bit Thumb instruction along with 32-bit ARM instruction set which will enhance the code density in restricted memory conditions while returning most of the ARM s performance. Features: Supported with point to point, point to multipoint and peer-topeer networking on proprietary stack. Direct Sequence Spread Spectrum technology. RF Data rate: 250kbps. Acknowledgement mode communication with retries. Power saving modes. Source/Destination addressing. Analog to Digital Conversion and Digital I/O line support. Each direct sequence channel has 64K unique network address. Configurable transmit power: Up to 0 dbm, 18 dbm and 30 dbm. Supports user application development. ISSN: Page 3267

3 Specification: Input Voltage: 3.3 V to 3.6 V. Frequency: ISM GHz. Transmit Current: 45 milli Ampere. Power down current: less than 10 micro Ampere. RF Data rate: 250 Kbps. Receiver Sensitivity: -92 dbm. Serial Data Rate: Up to baud. Supported Network: Peer to Peer, Point to Multipoint and Mesh Number of Channels: 16 Addressing Options: PAN ID, Channel and address C. Sensor unit A sensor (also called detector) is a converter that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. Three sensors are used in the project. They are MQ-2, HR-201 and LM-35 respectively. i) LM35 Precision Centigrade Temperature Sensors LM35 series Temperature Sensor is a precisely integrated circuit whose voltage output is linearly proportional to the centigrade temperature. These sensors have an added advantage over kelvin calibrated sensors and do not require the subtracting of constant voltage from its output to obtain convenient centigrade scaling. This sensor need not to be calibrated or trimmed to normal accuracy of ±1/4 C at room temperature and ±3/4 Cover a full -55 to +150 C temperature range. The low output impedance, linear output, and precise inherent calibration of these temperature sensors makes the interfacing to readout or control circuitry easily. These sensors can be used with single, plus or minus power supplies because it draws only 60 ma from its supply and has very low selfheating, less than 0.1 C in still air. Features of our offered Temperature Sensor are as follows: ii) Flammable Gas & Smoke Sensor (MQ-2) We took smoke sensor in providing quality tested Flammable Gas & Smoke Sensors that helps in detecting the presence of combustible smoke and gas at concentrations ranging from 300 to 10, 000 ppm. Due to their simple analog voltage interface, these sensors require just one analog input pin from the micro controller and process the output in the form of analog signals. Our product can work at varied temperature ranging from -20 to 50 C and consume less power, 150 ma to 5 V. iii). Humidity Sensor (HR201) Calibrated directly in Celsius (Centigrade) Linear a 10.0 mv/ C scale factor 0.5 C accuracy guaranteed (at a25 C) Rated for full b55 to a150 C range Suitable for remote applications Low cost due to wafer-level trimming Operates from 4 to 30 volts Less than 60 ma current drain Low self-heating, 0.08 C in still air Nonlinearity only g(/4 C typical Low impedance output, 0.1 X for 1 ma load Humidity Sensors are specifically fabricated from optimum grade organic macromolecule components. Owing to their low power consumption, quick response, high performance, wide measurement, excellent linearity, anti-pollution and optimum stability, our range is widely demanded in the market. ISSN: Page 3268

4 Some of the application areas of our Humidity Sensors are: Hospitals Storage and workshop Textile industry Tobacco and pharmaceutical field Meteorology III. SYSTEM SOFTWARE DESIGN The software coding for the hardware functionality is written in embedded C language in Keil Software. The TCP/IP layered model of IEEE standard is successfully implemented in embedded C language. A.Ethernet (ENC28J60) The ENC28J60 is a stand-alone Ethernet controller with an industry standard Serial Peripheral Interface (SPI). It is designed to serve as an Ethernet network Interface for any controller equipped with SPI.The ENC28J60 meets all of the IEEE specifica-tions. It incorporates a number of packet filtering schemes to limit incoming packets. It also provides an internal DMA module for fast data throughput and hard-ware assisted checksum calculation, which is used in various network protocols. Communication with the host controller is implemented via an interrupt pin and the SPI, with clock rates of up to 20 MHz. Two dedicated pins are used for LED link and network activity indication. Ethernet Controller Features IEEE compatible Ethernet controller Integrated MAC and 10BASE-T PHY Supports one 10BASE-T port with automatic polarity detection and correction Supports Full and Half-Duplex modes Programmable automatic retransmit on collision Programmable padding and CRC generation Programmable automatic rejection of erroneous packets SPI Interface with clock speeds up to 20 MHz IV RESULTS TESTING EMBEDDED WEB SERVER Initially, the target board is tested for the working of operating system which is done by connects to the target using the hyper terminal. Now the embedded web server is responding to the no.of client s connecter to server, request is made to the server, embedded web server, by typing the corresponding IP address of the server in the client s browser window. The user has to enter correct IP to access the server. This request is taken by the operating system of the client and given to the LAN controller of the client system. The LAN controller sends the request to the router that processes and checks for the system connected to the network with the particular IP address. If the IP address entered is correct and matches to that of the server, a request is sent to the LAN controller of the web based embedded server and a temporary session is established between the clients and server and a TCP/IP connection is establishes and the server starts sending the web pages to the all of its client. ISSN: Page 3269

5 VI. REFERENCES [1] Alen Rajan, Aby K. Thomas, Rejin Mathew, A Comparative Performance Analysis of ARM based Web Servers with Integrated and External Ethernet Interfaces for Industrial Applications, International Journal of Computer Applications ( ) Volume 44 No.21, April [2] MoGuan and Minghai GUI; Design and Implentation of an Embedded Web Server Based on ARM, IEEE International Conference on Software Engineering and Service Sciences, pp , July [3] Zhao Ruimei and Wang Mei; Design of ARM based Embedded Ethernet Interface. 2ndInternational Conference on Computer Engineering and technology, pp.v4-268-v4-270, April [4] Richard Opio Ocaya and Steven Rwabona Katashaya; A Low-cost Embedded Web-Server for an Institutional e- Learning Strategy, 3rd International Conference on Electronics Computer Technology, pp , April [5] Karia, D.C., Adajania, V., Agarwal, M and Dandekar, S.; Embedded Web Server Application Based Automation and Monitoring System, VII. BIODATA Above showed web page are requested by the client and served by the embedded web server which is ported on ARM7 processor. Client can interact with the machine through its own browser via these embedded web pages. Every client s control has been executed in industry via the embedded web server. A.shilpa received her B.Tech degree in Electronics & communication engineering from Sridevi women s engineering college in Presently she is pursuing M.Tech in Digital systems and computer electronics in E.C.E. Department from Sreenidhi Institute of Science and Technology since November V. FUTURE SCOPE With rapid development in the field of industrial process control demands for high data accuracy and reliability. This Embedded ARM System can adapt to the requirements as a whole. By making use of LPC 2148 RISC machine - An embedded database, the collected data can be stored on the server and can be used for further processing. As ARM core is a fully accustomed and provided with USB Host device video processing can also be implemented. ISSN: Page 3270