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LOOK MA, NO PC!

A $55 Webcam
by Steve Freyder, David Helland, & Bruce LIghtner

Start • Hardware Design • Picking a Camera • Cheap CMOS Cameras • PicoWeb Server Hardware • Firmware Functions • Software Design • PicoWeb Firmware • Java Applet • Smile • Source and PDF

If you think that itıs impossible to build a full function web camera that includes the camera, web server, network interface, and software for under $55, then keep reading!

There has been a battle brewing at the low end of network interface products for embedded applications. It seems that everyone is interested in getting their equipment hooked up and online as a network appliance. Until recently this was an expensive proposition requiring PCs, network interface cards, HTTP server software, and TCP/IP protocol stacks.

If you have a simple application that would benefit from Internet accessibility, such as providing a temperature reading, buying a PC and the necessary network software for such an application is probably out of the question. However, cheaper alternatives are available.

Cheap Web Servers

Early approaches to cutting the size and cost of embedded network controllers involved using single-board PCs (e.g., based on the 80188 or ı386EX). These are still reasonable solutions if your task requires a fair amount of computational effort. However, the cost of these solutions is generally well over $150. There are now several special-purpose chips that supply the network interface protocols required to hook up your favorite micro to the Internet.

For example, Hewlett-Packard has the Bfoot-10501 chip. It has a serial port to attach to your external device, and a 10BaseT Ethernet interface to connect everything to the ıNet. HPıs offering includes a web server, allowing a web browser to control and monitor your device. The HP device is relatively expensive ($240 in small quantities), but itıs unlikely to be cost effective until your quantities are high.

Something like the EmWare system allows many small devices to be connected to a serial network for the purposes of web access. However EmWareıs solution still requires a PC to provide a "gateway" to your local area network (LAN) and the Internet.

Another alternative is dial-up Internet access. ConnectOne, Scenix, and Epson have chips that can connect to the Internet via a modem (or terminal server). But, if you need a direct connection to your LAN, need high-speed access to your device, or canıt afford modems (or terminal servers) at both ends of your connection, these solutions are probably unacceptable.

A more cost-effective way of providing a web-based network interface with a direct connection to your LAN is the PicoWeb server ($79). This is a complete solution that provides a TCP/IP stack, an HTTP web server, and a 10BaseT Ethernet connection for your device. The PicoWeb server can stand alone as a web server without the need to interface to another microprocessor, or in many cases, to even write software. Right out of the box you can load your HTML code and images, plug the device into the LAN, and use your web browser to display web pages from the device.

The PicoWeb project was started by a group of friends who wanted to settle an argument about whether or not a single chip microprocessor could really deliver web pages. The result was an article demonstrating how to build "A $25 Web Server" in Circuit Cellar Online 1 (July, 1999) using a $6 Atmel microcontroller and a $9 PC ISA-bus network card, complete with all the necessary firmware and development system software.

Lightner Engineeringıs PicoWeb server is a commercial product spawned by that project. Even though the PicoWebıs microcontroller has only 8 KB of program memory and 512 bytes of RAM, it effectively delivers web pages and more. A 16-KB serial EEPROM chip adds storage for graphic images, HTML, and CGI programs. A built-in UART and about 16 unused general-purpose digital I/O lines provide the facilities to connect the PicoWeb server to a wide variety of user devices. Many project examples and the entire software development tool set can be found at the PicoWeb site (www.picoweb.net).

This article will show the power of the PicoWeb server by attaching it to a serial device (an inexpensive digital camera) and how to program the PicoWeb to acquire pictures from the camera so they can be transferred to a web browser for display. This project will work on both the $25 "home-grown" version of the PicoWeb server and the commercial version.

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