Reverse engineering wireless weather stations

lacrosse_wireless_temp_sensor

[Fred] got a La Crosse wireless weather station as a gift and thought the LCD display was great, but he was dismayed that there was no means of extracting the temperature data for use on a computer. He thought that the modular design of the system would make it great for use in his home automation project if he could only get his hands on the data.

He tore into the base station and started looking around for easy places to get at the data he was looking for. He thought about tapping into the bus that controls the LCD in hopes of finding an easy to decode signal, but the weather station used a proprietary chip with an integrated LCD controller, making it all but impossible. Instead, he started sniffing the data coming across the wireless link, and while he didn’t quite yet know what he was seeing, it was a start.

He sniffed the signals using Audacity, and eventually found that the base station received 40-bit data bursts from each sensor. He dug further, and with the help of some data he found online, he was able to decode the data packets. The last hurdle he ran into was figuring out how the system’s CRC encoding worked. It took a bit of work but he eventually got it, and can now record data packets knowing that the data has come over the air intact.

So far, it looks like his temperature monitoring system is working quite well, though he has several improvements planned for the near future. If you have a similar unit and are interested in extending its capabilities, [Fred] has posted plenty of code on his site.

Flashing Arduinos with a Zipit

zipit_arduino_flashing

[Giacomo] finds that every once in awhile, he needs to flash a sketch to an Arduino while on the go. While he doesn’t always carry his laptop with him, he almost certainly has his Zipit Z2 on hand. He prefers to use the Zipit because it’s tiny, it uses Debian, has built-in WiFi, and can run for about 5 hours before requiring a recharge. The only shortcoming is that the device lacks a serial port.

Following instructions we featured last year he added a serial port to his device, then built a small converter cable that allows him to connect it to virtually any Arduino. He says it only takes a moment to get avrdude up and running on the Zipit via apt-get, and once that’s done, he is in business. He wrote a short script that saves him from entering the flash command over and over, so the process couldn’t be simpler.

He does mention that since the Zipit does not have a DTR line, Arduino resetting must be done manually. For the convenience of flashing sketches from the palm of our hand, we can deal with that.

Check out the video below for a quick demonstration of his setup.

[Read more...]

The WALL-E Robot

[Dino's] latest Hack a Week project, the WALL-E Robot shows quite simply what you can create from a few dollars worth of toys from garage sales and cheap stores. When he found the WALL-E toy at a garage sale, Dino decided that he had to give it a brain. Using the geared motors from some Rumble Robots, the H-bridges from some $5 remote control cars (after his own H-bridges cooked themselves), an ultrasonic sensor and an Arduino, WALL-E was brought to life.

The WALL-E Robot might not be the brightest bot, or the most stable, but the project definitely demonstrates some effective scrounging for parts that would have done WALL-E proud. It also shows how even the most simple projects can cause the most headaches when they don’t go right. Check out the video after the break for the build details, a demonstration and to see a man talk to a toy robot.

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Hackaday Links: Monday June 13

Tim wrote in to tell us about this simple hack where he replaced the stock button lights with some really cool Blue LEDS on an ’87 BMW. He uses some capacitors, to achieve the effect that it takes a bit for the charge to drain out so the lights stay on for a bit after being turned off.  The lights themselves look really nice, so check out the pic.

Here’s an awesome coffee Table built using a large electrical board. It definitely would look good in anyone’s den, although it most likely has a low wife approval factor (WAF). This is actually based on a “motherboard wall that HAD covered before, but the “coffee table” form probably looks even better.

Finally, after the break is a video of someone washing an interactive art exhibit. Not sure if it qualifies as a hack, but it looks pretty cool to see lights following someone around when he’s washing the screen/window.

[Read more...]

An Autonomous Car Using a “Webcam”

This autonomous remote control-style car from Cornell students was designed for a senior level engineering course there. It’s main “sensor” is a low-res webcam style camera. As shown in the video after the break, this car does quite well staying within two black lines on a white surface using it’s vision processing. It also has an IR sensor to detect objects in front of the car and stop without crashing.

All “vision” computations are handled by an Atmel Mega644 MCU, an 8-bit processor. Because of the processing limits of this chip, much work had to be done to make this process computationally efficient. These students go through an incredibly detailed account of their project, focusing on the code and electrical design. Check out the video of their car in action after the break. [Read more...]

Wifi sniffing digital picture frame

[AUTUIN] sent in a tip for his wifi sniffing digital picture frame.

A soon-to-be-trashed Pentium II laptop was rescued from Free Geek Vancouver. A lot of coffee shops around Vancouver feature local art and free wifi, so [AUTUIN] decided to combine the two. The project is designed to hang on the wall of a cafe and sniff images transmitted on the wireless network – an invasion of privacy, but as [AUTUIN] says, “that’s kind of the point.”

After gutting the laptop and putting it in a custom picture frame, Driftnet, a program that listens network traffic and picks out images from TCP streams, was installed. [AUTUIN] tested his build with an open wireless connection in his building. The results provided a wonderful narrative that started with pictures from news sites than slowly devolved to pictures from a hot-or-not style website, an online dating site and finally pictures from the inevitable conclusion of that browsing session.

[AUTUIN] is now looking for either a brave or foolish local coffee shop in Vancouver to feature his wifi sniffing picture frame. We think this would be very amusing if we weren’t using that network, not that we have something to hide or anything.