Albuquerque, New Mexico
June 24, 2001
June 24, 2001
June 27, 2001
6.293.1 - 6.293.5
Connecting Embedded Systems to the Internet
Clare F. Cook Ferris State University
This paper deals with a proof-of-concept project that will demonstrate how sensor data can be retrieved over data networks. The project also tries to achieve this goal in a cost sensitive manner by utilizing open source software and low cost hardware. The concept is to provide environmental temperature sensing at a remote site and regularly update a web page with this temperature. The display of the data is controlled remotely through a web browser with the data returned to the browser. Commercial implementations of this technology are available today from a number of different vendors including EmWare1 and Picoweb2. These commercial products provide Internet connection to devices for obtaining data and providing control through a web browser.
A PIC (Peripheral Interface Computer) microprocessor is used to interface to temperature sensors for collection of data from them. This microprocessor is also interfaced to a host computer through a serial port. Most any PC, workstation, or embedded computer hardware can be supported in this system as LINUX is used for the operating system. The PIC controller doesn’t use an operating system and runs an assembly language program for interface to the PC and control of the temperature sensors. The host will run an http server for browser access. The http server chosen for the project was the thttpd server from ACME Labs Software3. This server is very memory conservative (executable size is approximately 50Kb) making it well suited for embedded systems. Compromising some features of the server is necessary to fit in this small footprint. CGI scripting is used as it allows external programs to query the sensor data or lets the web page be updated from sensor data that has been stored in a file. The programs for sending commands to the sensor controller, converting the data and placing the data in files are all implemented with PERL scripts.
The hardware of the system is broken down into two components: the host computer and the sensor controller. The host computer is the Intel 80386 based Explorer 2 development board and the sensor controller is the Microchip 16C74A PIC microcontroller. The Explorer 2 Proceedings of the 2001 American Society for Engineering Education Annual Conference and Exposition Copyright 2001, American Society for Engineering Education
Cook, C. (2001, June), Connecting Embedded Systems To The Internet Paper presented at 2001 Annual Conference, Albuquerque, New Mexico. https://peer.asee.org/9032
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