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The Axis 2100 - a Linux-powered network camera

The Axis 2100 is exactly what it claims to be - a network camera. It's shaped like a flat tube, with a lens on one end, and a twisted-pair ethernet connector on the other. It runs its own web server internally - you can point a web browser directly at the camera and see what it's looking at. You can get either still images, or streaming video at a rate of 3-10 frames/second, depending on the image resolution and compression that you use. It can take pictures at either 640x480 or 320x240 pixels.

If you don't want to direct viewers to the camera directly, the 2100 can also be configured to automatically upload images via FTP to a remote server every so often.

For the curious, the lowest price we found for this unit (after not a huge amount of research) was $469 from CDW.

Setting it up. Getting the Axis 2100 on the net took all of about five minutes - though somebody who was not familiar with system and network administration might have a bit of a harder time. The camera may run

The Axis 2100

Linux, but the people who buy it are clearly expected to be running Windows. Once you have gotten an IP address for the camera, you need only run the installer application provided with the camera, and it will be up and running.

Or so they say. I run Linux, and there's no installer program for Linux. Instead, you have to configure your system to give an IP address to the camera via either ARP or BOOTP. ARP is the simpler solution, since you don't have to mess with any running daemons. Just get the MAC address for the camera (handily printed on the bottom of the case) and run a command like:

	arp -s camera mac-address pub

Administration of the camera is all done through a series of web pages. Whoever writes HTML for Axis suffers from that terrible disease that makes people want to use microscopic fonts that us folks who are no longer in our twenties have to squint at to read, but everything else is straightforward. You can create accounts on the camera, with varying levels of privilege. You can also restrict access as need be.

Anyway, as I said, five minutes later I could connect to the camera, and realize that I was now making an intimate view of my office available to the net as a whole. Not being interested in running the "Jonnicam", I pointed it out the window instead.

What's inside. The camera runs a special-purpose processor called the "Etrax 100," which is produced by Axis. They have ported Linux to this chip (and posted the source as the GPL requires). There is no obvious way to log into the camera, but it is running an FTP daemon which, among other things, lets you dig around in /proc. We saved a few /proc files for your reading pleasure.

From /proc we learn that the camera is running a 2.0.33 kernel; it has 5.6MB of memory available, but isn't using all of it. The ethernet controller appears to be built into the CPU itself; it also has two serial ports (one of which is available on the back and can drive a modem). It's a 99.58 bogomips system.

On using Linux in a network camera. Bjorn Wesen of Axis was kind enough to answer some of our questions regarding this device. The choice of Linux came about partly because it had already been ported to the Etrax processor (which is available as a product in its own right). They had considered several alternatives, but it came down to Linux because it was available, and "a desire to focus the development efforts of the camera team to what they were best at - imaging HW/SW and picture transfer - instead of the developers having to learn or build a new OS."

The developers at Axis are pleased with the choice. The availability of source and ability to make quick fixes is crucial when designing a product of this type. Since the engineers also run Linux on their desktops, they can do much of their development in that environment, where it is easier. Only occasionally do they need to cross-compile code and download it into a real camera.

Axis ended up rolling its own distribution for the camera. Since it uses their own processor, there are no prepackaged distributions available for their use. And, in any case, they had to be extremely selective about what actually went into the device. Only crucial daemons - and trimmed-down ones at that - can fit, and libc had to be thinned as well.

The camera also uses Axis's Journaling Flash File System, which allows the device to run out of flash memory. It's a live filesystem, in that you can go in and change things. But when you pull the plug, everything is still there - no need to wait while the camera runs fsck the next time you turn it on. Embedded systems, of course, need this sort of "instant on" functionality. Axis has made JFFS available under the GPL - but it currently only works with the 2.0 kernel. (At least, the version supplied by Axis is limited to 2.0; see the Memory Technology Device site for a 2.3 version).

But the real question that comes to mind is this: given that the camera is running Linux, is it possible to write specialized code to run inside the camera itself? Axis makes available everything that is needed to do this: versions of the compiler and libraries are available on the Axis developer site. It's mostly a matter of cross-compiling the code and FTPing it into the camera.

Axis does not officially support tweaking the camera's code in this way - yet. "We get requests every day from people who want to add their own changes to the 2100 - ranging from customized picture transfer protocols, to new picture encodings or just changing the HTML." With an upcoming firmware upgrade, however, support for uploading code into the camera will be official. There might just even be some documentation on how to do it as well. Then another advantage of using Linux becomes clear: "Fortunately, we can then just tell the customers that 'It's Linux, go buy a Linux book and roll your own!' instead of having to teach them an entire proprietary operating-system."

Conclusion. As a gadget, the 2100 scores well. It makes it easy to set up a camera anywhere that you have networking available. The Axis 2100 is also a nice example of what can be done with embedded Linux - you really can cram it into a tiny box and make it do cool things. The real value of Linux in this application, however, may well be that it allows the customer to reprogram the device as needed. Wouldn't it be nice if more of our devices were open in this manner?