Primer On Bluetooth Low Energy

August 29, 2013 by Mike Szczys 14 Comments

We’re sure that, like us, you’ve heard at least something about Bluetooth Low Energy (BLE). Blutooth 4.0 is another name for BLE and it’s already available in some smartphones; starting with the iPhone 4S, BlackBerry 10, and with Android support added in 4.3 — Jelly Bean. Here’s your chance to get acquainted which what the specification brings to the table. The source material (which we’ll talk about below) provides a ton of background. But if you want a succinct overview check out [Gervasi’s] summary of Bluetooth Low Energy.

We won’t republish the technical details here as both articles do a great job of covering those. Here’s what you should take away from BLE: It’s meant for use with devices running off of a tiny power source. The one outlined in both articles is a coin-cell. But we prefer to think of the future that is energy harvesting. Peak current is limited to 15 mA. This does limit the throughput, but think sensors, not Bluetooth headsets. You just don’t need to push all that much data from these devices. A cleverly designed energy harvesting circuit should be able to implement BLE devices with no battery whatsoever.

We did mention a deeper exploration of the standard. The image above comes from this BLE Primer for Developers. Add it to your weekend reading.

[via Reddit]

Spoofing WiFi AP Based Geolocation

August 27, 2013 by Mike Szczys 39 Comments

[Pierre Dandumont] just finished up a little project that will give Google Maps’ location feature a run for its money. It’s a technique that spoofs WiFi networks in order to relocate the positional data reported via WiFi networks.

He starts with an explanation of the different ways modern devices acquire location data. GPS is the obvious, and mobile network triangulation is pretty well know. But using WiFi networks may be a new trick for you. We’re not 100% certain but we think Google is able to look up location data based on known IP addresses for WiFi access points (this would be a good comments discussion). To trick the system all you have to do is feed some captured AP data into the computer before Google Maps tried to lock onto a location. The video after the break shows Maps with the legit location displayed. After running a quick script whose output is shown above the map position is changed to the spoofed location.

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Wireless Marble Labyrinth Uses TI Dev Hardware

August 11, 2013 by Mike Szczys 3 Comments

wireless-marble-labrinth-using-ti-dev-hardware

There’s so much affordable dev hardware out there these days that you can do a lot without even touching a soldering iron. This is a prime example. Texas Instruments software Engineer [Jordan Wills] recently completed this wirelessly controlled marble labyrinth.

Marble mazes like this are a popular targets for electronic tinkering. We’ve seen smartphones used as the controller, and others that dispense chocolate candy. This time around [Jordan] stuck with the store-bought game to simplify the build. A coworker helped by swapping the two control knobs with servo motors. These interface with a Stellaris Launchpad that has a SensorHub booster pack (shield) and CC2533 radio transceiver module. The same hardware makes up the remote unit as well. This turns the remote into an air mouse by reading the gyroscope, accelerometer, and magnetometer from the booster pack.

He doesn’t specifically mention it in his project log, but we think the magnetometer is used to sync orientation between the base unit and the user remote. Even though the board for the base unit is mounted at 90 degrees compared to how you hold the remote, you should still be able to adjust for the readings in code, right?

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Electric Imp As An Internet To RF Gateway

July 25, 2013 by Mike Szczys 7 Comments

a-little-automation-with-the-electric-imp

This project is a study in connecting several different families of hobby electronic hardware. The image above shows the Electric Imp side of things. It bridges its Internet connection with the RF connections of the rest of the project.

The Imp is a peculiar (intriguing?) piece of hardware. Take a look at [Brian Benchoff’s] hand’s on experience with the SD form factor hardware which is not an SD card at all. It’s an embedded system which uses light programming and a cloud-based software setup to bring wireless Internet to your projects.

In this case [Stanley Seow] started wondering if he needed multiple Imps to connect different parts of his setup. A bit of head scratching led him to the use of nRF24L01 modules which are cheap and easy to use Radio Frequency transceiver boards. He took a partially finished driver project and brought it home to play nicely with the Imp. Now he can use the system to communicate with other components which will eventually be used for home automation. Right now his proof of concept issues wireless commands to an Arduino driving a strip of LEDs.

Wireless Toilet Occupancy Sensor

July 18, 2013 by Mike Szczys 28 Comments

toilet-occupancy-sensor

It’s a bit awkward for all parties involved if someone is waiting right outside the bathroom door. This system helps to alleviate that issue by letting the next user know when the loo is available. [Akiba] has been working with the folks at Loftworks, a design company in Tokyo, to get the status beacons seen above up and running.

The staff is mostly women and there is just one single stall women’s toilet on each of the three floors. The boxes above represent the three stalls, using colored light to indicate if a bathroom is available or in use. Detection is based on a PIR motion sensor in each stall. They communicate back with the display units wirelessly, which initially presented quite a problem. The doors on the bathroom are steel, and when closed they effectively block communications. The 900 MHz radios used in the system are on the 802.15.4 protocol. But they can be set a couple of different ways by moving resistors. Each came configured for the fasted data throughput, but that’s not really necessary. By changing to a slower configuration [Akiba] was able to fix the communications problems.

We remember seeing a similar bathroom indicator in a links post some time ago.

Kebab Skewer Quadcopter

July 11, 2013 by Mike Szczys 13 Comments

kebab-skewer-quadcopter

Quadcopters are the epitome of high-tech hobby electronics. We’re quite used to seeing the frames built out of modern materials (carbon fiber, 3d printed, etc). But it’s pretty hard to beat the strength-to-weight ratio of kebab skewers. You heard us correctly. [Shiny Shez] built his quadcopter frame from kebab skewers.

You might want to get that Boy Scout Handbook out and brush up on your lashing skills. Lashing is a method of using rope (string in this case) to fasten together wooden sticks (bamboo kebab skewers). Once the lashed joints are precisely oriented [Shiny] applies a liberal coat of super glue to cement them in place.

He went the easy route when it comes to control hardware. You can get spare parts for the Husban X4, a commercially available quadcopter. Its main controller is used here. The single board controls the motors, monitors an IMU to keep the aircraft stable while in flight, and includes a wireless transceiver. On the receiving side [Shiny] uses an Arduino with a wireless module. This way he can control the quadcopter from his laptop, or go one step further and use an Android phone.

Reverse Engineering A Wireless Protocol

July 1, 2013 by Brian Benchoff 31 Comments

logic

Like all good tinkerers, [Andrew] decided to figure out how his wireless security system worked. Yes, it’s an exercise in reverse engineering, and one of the best we’ve seen to date.

After breaking out the handheld spectrum analyzer and TV tuner SDR, [Andrew] cracked open a few devices and had a gander at the circuit boards. The keypad, PIR sensor, and base station all used a TI radio chip – the CC11xx series – that uses SPI to communicate with a microcontroller.

Attaching a logic analyzer directly to the radio chip and reading the bits directly, [Andrew] started getting some very good, if hard to understand data. From the security system specs, he knew it used a ’20-bit code’, but the packets he was reading off the SPI bus were 48 bits long. The part of this code was probably the system’s address, but how exactly does the system read its sensors?

The easiest way to figure this out was to toggle a few of the sensors and look at the data being transmitted. With a good bit of reasoning, [Andrew] figured out how the alarm system’s code worked. This theory was tested by connecting one of the radios up to an Arduino and having his suspicions confirmed.

While [Andrew]’s adventure in reverse engineering is only a benefit for people with this model of security system, it’s a wonderful insight into how to tear things apart and understand them.