Jump In When The Water Is Just Right With A Wireless Swimming Pool Thermometer

[David]’s family acquired a swimming pool. While it’s not his favorite activity in the world, every now and then he’ll indulge in the blue plastic bin full of water occupying previously pristine land in his backyard.

As he says, cool beer is pleasant, but cool water tends to put a damper on the experience. Rather than do something pedestrian like touch the water himself to discover its temperature; he saw an opportunity for a fun little project in a wireless temperature monitor.

The heart of the device is a Telecom Design TD1208 which runs on the French SigFox network. For a small fee any device on the network can send up to 140 12byte packets of data a day. Not a lot, but certainly acceptable for the Microchip MCP9700 temperature sensor it uses. He got the board up and running, and even made his own custom helical coil antenna.

The case was 3D printed out of PLA. It’s a tiered cylindrical bobber. The wider top section floats on the water and the base acts as a ballast, holding the battery and sensor.  The bobber is powered by a combination of  a questionable Chinese lithium battery, charging circuit, and solar panel. [Dave] was keen to point out that the battery is, technically, water cooled.

He wrapped up the code for the bobber and used SigFox’s SDK to build a nice web interface. Now, when the rare mood strikes him, he can remain inside if the conditions aren’t right for a swim.

Hands-on the AND!XOR Unofficial DEF CON Badge

DEF CON 24 is still about two weeks away but we managed to get our hands on a hardware badge early. This is not the official hardware — there’s no way they’d let us leak that early. Although it may be unofficial in the sense that it won’t get you into the con, I’m declaring the AND!XOR badge to be officially awesome. I’ll walk you through it. There’s also a video below.

Over the past several years, building your own electronic badge has become an impromptu event. People who met at DEF CON and have been returning year after year spend the time in between coming up with great ideas and building as many badges as they can leading up to the event. This is how I met the trio who built this badge — AND!XORAndrew Riley, and Jorge Lacoste — last year they invited me up to their room where they were assembling the last of the Crypto Badges. Go check out my guide to 2015 Unofficial DEF CON badges for more on that story (and a video of the AM transmissions that badge was capable of).

The outline is this year’s badge is of course Bender from Futurama. Both eyes are RGB LEDs, with another half dozen located at different points around his head. The microcontroller, an STM32F103 ARM Cortex-M0 Cortex-M3, sits in a diamond pattern between his eyes. Above the eyes you’ll find 16 Mbit of flash, a 128×64 OLED screen, and a reset button. The user inputs are five switches and the badge is powered by three AA batteries found on the flip side.

bender's-nose-closeup

That alone makes an interesting piece of hardware, but the RFM69W module makes all of the badges interactive. The spring coming off the top of Bender’s dome is a coil antenna for the 433 MHz communications. I only have the one badge on hand so I couldn’t delve too deeply what interactive tricks a large pool of badges will perform, but the menu hints at a structure in place for some very fun and interesting applications.

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