Monitoring the status of a unisex bathroom

Years ago, someone at [Chuck]’s job came up with the brilliant solution of an indicator to display if the unisex bathroom is currently vacant, a men’s bathroom, or a women’s bathroom. The old system worked well, but [Chuck] thought it would be a great idea to display the current status of the bathroom on the large TV in the office, saving his coworkers from getting up only to wait in line until the bathroom became vacant.

Like the previous paper sign, [Chuck]’s build has three statuses: a men’s room, a women’s room, and vacant with a manual dial that is turned whenever someone is entering or leaving. The new build vastly improves on the paper-based indicator by using a laser cut indicator on a rotary switch.

The electronics are dead simple; just an XBee and a Explorer USB board. Whenever the switch state is changed, the XBee sends a bit of data off to a mac mini and displays the status on the office TV. It may be funny to our immature sense of humor, but it’s still a very nice project.

Wireless camera mount offers pan and tilt functions

[Chris] put together a bunch of common components to create this wireless pan and tilt system for a security camera or a robot.

The motorized base is simple enough, using two servos to make up a mount for the digital camera. In this case he used a parts package which is designed to mount the servos perpendicular to each other. You could also 3D print, our build your own brackets quite easily. The control circuitry consists of a pair of PIC 18LF4520 microcontrollers and a set of Xbee modules. This is where the wireless connectivity comes in.

On the transmitter side, a pair of potentiometers are read by the microcontroller’s ADC and translated into position values. The receiver takes those values and drives the servo motors accordingly. In the clip after the break [Chris] is using micro trimpots which require a screw driver to adjust. You might want to hit the parts bin and see if you can get some that have a more user-friendly shaft or knob.

Unfortunately this system doesn’t transmit video. But WiFi webcams are getting quite affordable so that might be a good option in this case. Continue reading “Wireless camera mount offers pan and tilt functions”

Monitoring home electricity usage via a tidy wall display


[Janne Mäntyharju] wanted to get an idea as to how much electricity he consumed in his new home, mainly to see if using his fireplace for additional heat had any effect on his bill. Luckily his power meter was mounted in the utility room of his house, making it easy to keep tabs on his usage.

His meter features a small LED that blinks a fixed number of times per consumed Kilowatt hour, so he mounted a photoresistor and ATtiny2313 above it to detect the light pulses. [Janne’s] server polls the microcontroller every 5 minutes over an XBee connection, recording the power usage in an SQL database for further analysis. From this database, he generates graphs showing both the temperature in his home as well as the average electricity usage for the specified time period.

[Janne] also wanted to make the data easily accessible, so he constructed a wall-mounted display using a Beagleboard and digital picture frame. The display not only shows his electricity usage, but it toggles between the weather, calendar events, IRC logs, and pictures from his security camera.

We’ve certainly seen this sort of electric meter monitoring before, but it serves as a quick reminder that given the right tools, watching your power usage (among other things) can be as easy as taking a quick glance over at the wall.

DIY quadcopter for around $200

We think [FlorianH] did a bang-up job of prototyping his Minima Quadcopter on the cheap. The total bill comes in right around $200 and we’re very happy with the quality of parts as well as the results.

Here you can see the top of the double-sided board which he etched to host all of the components. At each corner there is a power MOSFET which drives the motor. At first glance we thought that the Xbee module was acting as the radio control and processer as well. But on the underside you’ll find an ATmega32 which is responsible for reading the Gyroscope sensor and Accelerometer, processing these signals and driving each MOSFET via PWM lines to provide stability.

You can see some flight tests after the break. [FlorianH] mentions that there is some oscillation in the feedback loop when both the gyro and accelerometer are used. But cut the accelerometer out of the equation and the platform is rock-solid.

This build uses carbon tubes to mount the motors, which we think will be a little more robust than the all-PCB designs are.

Continue reading “DIY quadcopter for around $200″

Get neck-deep into ZigBee

Here’s a bulky tutorial that will round-out your understanding of ZigBee wireless communications (translated). The protocol is great for hobby electronics projects because it uses low-power short range wireless devices to build a mesh network. The guide covers both hardware and software, but also takes the time to explain what that hardware is doing in the background.

As you can see, several different renditions of an XBee module are used as examples. They pretty much all rely on a series of SparkFun breakout boards that each serve different purposes. Once you’ve acquired these modules, there’s a fair number of choices needed to configure them to play nicely with each other. We read most of the tutorial (we’ll save the rest for later enjoyment) and had no problem following along even without owning the hardware or being able to use the interface as we learned.

Whenever we cover XBee modules we always like to mention that it’s quite easy to use these for remote sensors with no additional microcontroller needed.

WiFi garage door opener makes forgotten keys a thing of the past


[Tod’s] daughter has a habit of forgetting to take a house key along with her, so he was looking for a way to make accessing the house easier in a pinch. He had tried wireless garage door keypads in the past, but their performance was so-so at best. After scouring the market for commercial solutions and checking out the work of other hackers, he decided that he needed to craft a custom solution of his own.

He started shopping around for wireless-enabled microcontrollers and settled on a Roving Networks RN-XV module, which is designed as a drop-in replacement for an XBee. Paired with a 5v to 3.3v power adapter, the RN-XV is nearly all he needed to interface his iPhone with his garage door opener.

The microcontroller has enough GPIO pins to control the garage door, while also monitoring the door’s status using a simple magnet/reed switch combo. A web server in [Tod’s] house takes input from any phone connected to his wireless LAN and relays the open/close commands to the opener. The opener in turn returns status messages to him via the web interface.

We really like the system’s simple design, and as long as [Tod] has turned WPS off at home, he really shouldn’t have to worry too much about unauthorized entry.

Xbee Wireless Servo Control

Servo control is good, but wireless control is even better. This hack by [PyroElectro Tutorials] shows you how to do this wirelessly using two Xbee modules. There’s also a great example in the video after the break of this “hacking platform” used to control an animatronic head’s eyes. (we’ve featured the eyes here before).

In this control scheme, communication is one way only. An Xbee module is used as the transmitter, and the other as the receiver. The tutorial does a great job of explaining the parts used and gives links for purchasing the components if needed. It even goes over some very basic servo theory and gives schematics as well as assembly pictures. Transmitter and receiver firmware files are also available to download, so there’s nothing keeping you from trying it! Join us after the break to see the working example.

Continue reading “Xbee Wireless Servo Control”