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.

RF Wireless Kernel Module For Raspberry Pi, BeagleBone And Others

June 27, 2013 by Mike Szczys 21 Comments

rfm12b-kernel-module

If you’ve done any wireless work with hobby electronics you probably recognize this part. The green PCB is an RFM12B wireless board. They come in a few different operating bandwidths, the 433 MHz is probably the most common. They’re super easy to interface with a small microcontroller but what about an embedded Linux board? That is the focus of this project, which builds a kernel driver for the RF module.

You can get your own RFM12B for a few bucks. They’re quite versatile when paired, but a lot of inexpensive wireless consumer goods operate on this band so the board can be used to send commands to wireless outlets, light fixtures, etc. [Georg] has been working with the BeagleBone, BeagleBone Black, and Raspberry Pi. His software package lets you build a kernel module to add an entry for the device into the /dev directory of a Linux system. So far the three boards listed are all that’s supported, but if you have five I/O pins available it should be a snap to tailor this to other hardware.

Wondering what else you can do with the setup? This will get the receiving end of a text-messaging doorbell up and running in no time.

Continue reading “RF Wireless Kernel Module For Raspberry Pi, BeagleBone And Others” →

TI’s CC3000 WiFi Chip Gets A Library

June 24, 2013 by Brian Benchoff 43 Comments

About six months ago, Texas Instruments released a simple, cheap, single-chip WiFi module. At $10 a piece in quantities of 1000, the CC3000 is a much better solution to the problem of an ‘Internet of Things’ than a $50 Arduino Ethernet modules, or even the $30 Electric Imp. All indications, especially the frequent out of stock status for the dev board on TI’s web site, show the CC3000 will be a popular chip, but until now we haven’t seen a CC3000 library for the Arduino or other microcontrollers.

[Chris] just solved that problem for us with a CC3000 WiFi library for the Arduino. He ported TI’s MSP430 CC3000 library to the Arduino, allowing even the bare-bones Arduino Uno to connect to a WiFi network with just a handful of parts. The code itself takes about 12k of Flash and 350 bytes of RAM, giving anyone using the CC3000 enough room left over to do some really interesting stuff. There’s even a slimmed down library that uses somewhere between 2k and 6k of Flash, making an ATtiny-powered web server a reality.

There are a few caveats in using the CC3000 with an Arduino; it’s a 3.3 Volt part, so you’ll need a level shifter or some resistors. Also, the chip draws about 250 mA when it’s being used, so you’ll need a beefy battery if you want your project to last an entire day of use.

Now that the library is out of the way, be on the lookout for a CC3000 breakout board. Here’s one, but expect some more on the market soon.

Letting Bluetooth Take The Wires Out Of Your Headphones

June 17, 2013 by Mike Szczys 11 Comments

bt-wireless-headphones

This picture shows the gist of [Alan’s] hack to transition his wired headphone to internalize a Bluetooth audio receiver (translated).

He starts with a pair of wired “ear muff” style headphones and an aftermarket Bluetooth audio adapter that he’s been using with them. But if you’re not going to plug them into the audio source why have six feet of extra wire hanging about? [Alan] ditched the plastic case surrounding the Bluetooth hardware and cracked open the earpieces to find room for it. It’s a tight fit but there was just enough room.

It is unfortunate that the headphone design doesn’t already have a wired crossover hidden in the arc connecting the earpieces. Alan strung some of that red wire himself to connect the two speakers. The board is mounted so that the USB port is located where the wires used to enter the plastic body. This makes it a snap to plug them in when they need a recharge.

You can play a little “Where’s Waldo” with this one by trying to spot the Raspberry Pi in his build log.

Wireless Unread Email Counter Tells You How Busy You’re Not

June 8, 2013 by Brian Benchoff 12 Comments

counter

One of the marks of how busy you are – or how well your spam filters are set up – is how many unread emails you have in your inbox. [trumpkin] over on Instructables posted a great tutorial for making a wireless counter that displays the number of unread emails in your Gmail account.

[trumpkin] used a tiny and inexpensive 419 MHz transmitter and receiver combo to make this project work. On his desktop, he wired up a USB to UART bridge attached to the transmitter. For the receiver side, an ATMega328 reads the data coming off the receiver and displays the number of unread emails on two seven-segment displays.

The wireless device runs off of two AA batteries and should provide enough power to keep the email monitor running for a long time. More than enough time for your inbox to fill up and for you to become overwhelmed with the work you should be doing.