[Dodgy] wrote in to talk about his power meter data harvesting programs. This uses the same hardware by CurrentCost as the hack we looked at over the weekend but [Dodgy's] implementation is different. It’s separated into two parts, the first is a webserver written in C that harvests the data and makes it available at an address on the network, the second is written in Perl to format and upload data to Google PowerMeter.

The C program serves data on a configurable port, defaulting to 3090. All of the data can be accessed in one line of code by loading http://127.0.0.1:3090, or individually with subdirectories like /watts, /time, or /tempr. From there you can do what you want with the data. The second part of [Dodgy's] suite is a Perl script that polls the C server and sends the data to your Google account.

One thing that interests us is his comment that you should be able to compile the server side C code for an embedded device. It would be a nice energy savings to be able to upload data regularly without a PC running constantly.

The Arduino platform should be perfect for throwing together a lightweight webserver because of the availability of quality shields that take care of the hardware for you. As [Ovidiu Predescu] found, there are a few hiccups along the way and he’s put together a guide that covers the workarounds. Specifically, using an Ethernet shield and data logging shield at the same time produces a bus conflict which he sidesteps by cutting the CS pin trace on the data logging board and moving it to a different pin. There is also a bug with one of the chips on the Ethernet shield that is fixed using a similar method. So if you’re not just going to etch your own webserver hardware maybe this is the next best thing.

Within a ten-hour window [Wes Brown] threw together this toaster with a web interface for one of his classes. He sourced the WIZnet embedded webserver for the project but this could be pulled off with a homebrew webserver as well. When you point your browser to the correct address you’re greeted with images of bread that have been charred to various degrees. This greatly complicates the act of making breakfast while at the same time presenting a possible fire hazard. Check out the video after the break.

Reader [john] finished up his home power monitor over the holiday weekend. It uses a pair of current transducers clamped onto the mains. These output 0-3V and are read by the Arduino’s ADC. The Arduino averages samples over a 20 second period, calculates power used, and uploads it using an Ethernet Shield. The shield can’t do DNS lookups, so he uses a WRT54G to negotiate with the remote webserver. He admits that the system could be more accurate; it can’t detect small loads like wall warts. He also says that money could be saved by talking serial to the router instead of over ethernet. Here are the current usage charts.

You can find many power monitor projects like this in out Home Hacks category.

On a recent trip to New York City, [sherri] noticed the abundant “NYPD Security Camera” signage. She Ò on her little sousveillance tour and did some digging to learn more about the system. According to a recent NY Post article, the city intends to have 2,000 cameras installed by 2009. Each unit has at least two cameras, an onboard DVR, battery backup, a webserver, and wireless connection. The CrimeEye product line is manufactured by Total Recall—the people who brought you BABYWATCH. While the company site doesn’t list any specs, we found a price list that was provided to New York State. Each unit lists for $28-39K. They can have image sensors up to 2 megapixels, hold 30fps video for 5-15days, and transmit wirelessly on the 4.9GHz public safety band.

[sherri] wonders what systems are in place to guarantee the security of the camera network and to make sure the data is handled properly. We’ve seen bad implementations of cameras with webservers
in the past. She suggests a third-party system to verify security, operation, and storage. Right now there’s no reason the government won’t use footage for invasive data mining. As a publicly funded system monitoring public areas, we see no reason why the video streams from these devices shouldn’t be widely available.

[Thanks Tendency]

If you are an Atmel fan, you may enjoy this webserver built around the ATmega88. Since it has full TCP and HTTP support, communication can be done using a standard web browser on any system. We also noticed that the code uses AVR Libc and the processor can be replaced with an ATmega168, both used on the Arduino platform. Honestly, we think the most interesting part about this project is the firmware. The author has assumed that the webserver will only be sending one packet per request and the code is optimized for this setup. This leaves around 50% of the memory for the web application.

[via YourITronics]