Bluetooth control in a power strip

[Mansour] had a ceramic space heater mounted near the ceiling of his room. Since heat rises this is not the best design. He upgraded to an infrared heater which works a lot better, but lacks the timer function he used on the old unit. His solution wasn’t just to add a timer. He ended up building a Bluetooth module into a power strip in order to control the device wirelessly. He ends up losing all but two outlets on the strip, but everything fits inside the original case so we think it’s a reasonable trade-off.

He uses relays on both the live and neutral wires to switch the two outlets. These are driven via MOSFETs to protect the ATmega168 which controls the board. The microcontroller and Bluetooth module both need a regulated DC power source, so he included a transformer and regulator in the mix. After the break you can see him demonstrating the system using two lamps. There’s even a terminal interface which lets you select different control commands by sending the appropriate character. This interface makes script a breeze.

At least this power strip doesn’t spy on you.

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Adding Bluetooth audio playback to a Toyota Matrix

In this project [Ryan] shows how he added Bluetooth audio to the stock stereo of his Toyota Matrix. The work he did with his add-on hardware is quite good. And the installation was surprisingly easy. For example, the dashboard bezel which is hanging in the foreground of this picture simply pulls off without the need for any tools. Also, the CD changer input for the stereo is what he uses to patch into the system. It just happened to have a 0.1″ pin header so finding a connector that would work wasn’t a problem.

As for the add-on hardware, he built his own circuit board around an ATmega168 microcontroller and Bluegiga WT32 Bluetooth module. To connect to the car’s data system he went with an RS485 driver chip. It’s not quite the right part but it works well enough for his purposes. So far he can get audio playback working and plans to add support for hands free phone calls and displaying audio track information. Hey, maybe he’ll even add some extra shake-based automation; who knows?

Get a look at the install in the clip after the break.

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Six-digit VFD alarm clock

[Haris Andrianakis] just finished building this very clean-looking vacuum fluorescent display clock. It shows six digits using IV-11 tubes, and also has a half-dozen RGB LEDs to spice things up (check out the video after the break for an example). An ATmega168 drives the device, controlling the display and serving as a battery-backed real-time clock.

As with any tube-based clock there’s a fair amount of work that goes into driving the display. Each tube has a filament which requires 1.2V, and the segments themselves need 60 volts to light up. The microcontroller is not hard to protect; this is done with a series of transistor-based circuits used for switching. But the need for three voltages (to power microcontroller, filament, and segments) means a more complex PSU design. [Haris] chose to use a MAX6921 to simplify the process.

If you’re considering building something like this, we’d recommend looking for some 12-segment tubes. As we’ve seen before, they can display letters as well as numbers in case you wish to repurpose the device in the future.

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Color changing coaster has a built-in drink detector

[Robert] put together his own illuminated coasters that know when they hold a drink. They look fantastic, thanks to professionally produced PCBs and a layered, laser-cut acrylic case. They’re much like the pagers given to restaurant-goes who are waiting for tables, but this version is much fancier (and doesn’t include the vibrating/paging feature).

The RGB-LED board is a previous project which was developed using eight surface mount RGB LED modules around a circular board. It uses an ATmega168 paired with an MBI5168 constant-current LED sink driver. The coaster enclosure gave him room for a few more items, like the pair of AA batteries which work in conjunction with a boost converter to power the device. It also houses an IR reflectance sensor which is used to detect the presence of a drink on the coaster. This is important since an on-occupied coaster looks like it would be blindingly bright if there wasn’t a glass to diffuse the intensity of the LEDs.

He mentions that incandescent light bulbs mess with the IR reflectance sensor. But there must be some way to account for ambient conditions with the code, right?

WiFi experiments with ATtiny microcontrollers

[Quinn Dunki] got some free stuff from Element14 to evaluate, including this Mircrochip WiFi module. It’s been used as the centerpiece of an Arduino shield in the past, and she grabbed a copy of that library to see if it would play nicely with an ATtiny chip. What follows is a struggle to de-Arduino the code so that it’s portable for all AVR controllers.

This module is one of the least expensive ways to add WiFi to a project, coming in at around $23. But it’s not really an all-in-one solution as there’s still a huge software hurdle to cross. The hardware provides access to to radio functions needed to communicate with the network, but you need to supply the TCP/IP stack and everything that supports it. Hence the re-use of the Arduino library.

Battling adversity [Quinn] fought the good fight with this one. Switching from an ATtiny to the ATmega168, compiling more code, and troubleshooting the process. She used a single LED as feedback, and can get some connectivity with her hotspot. But to this point she hasn’t gotten everything up and running.

We’re hot for an AVR WiFi solution that is cheap and easy to use. But as we see here, the software is complex and perhaps best left up to beefier hardware like the ARM controllers. What do you think?

Microcontroller comm with a computer monitor

Prolific Hack a Day author [Mike S] has been playing in his lab again and he’s come up with a neat way to talk to microcontrollers with an LCD monitor. The basic idea behind [Mike]’s work isn’t much different from the weird and/or cool Timex Datalink watch from the 1990s.

Despite the fancy dev board, the hardware is very simple – a photoresistor is pointed at a computer monitor and reads bits using Manchester encoding. The computer flashes a series of black and white screens thanks to a simple Javascript/HTML page, and data is (mostly) transmitted to the micro. [Mike] says he has about a failed message about 60% of the time, and he’s not quite sure where the problem is. He’s looking into another kind of Manchester encoding that uses samples instead of edges, so we hope everything works out for him.

This build is very similar – and was inspired by – an earlier post about microcontroller communication with flashing lights. Still, [Mike]’s build reminds us of the strangely futuristic Ironman watch we had in ’97. Check out [Mike]’s demo of his computer/micro comm link after the break and his code on github.

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FIGnition FLINT is a stripboard build of the simple computer

If you want people to really be impressed by your projects it’s often better not to have a fully finished look. In this case, we think hooking the stripboard version of FIGnition up to your TV will raise a lot more eyebrows than the PCB version will.

[Julian] put together a guide to building the computer on strip board. He’s using his own Java application for laying out circuits on this versatile prototyping substrate. This tool is worth a look as it may simplify those point-to-point solder prototypes you’ve been agonizing over. You’ll have to do some poking around on his site to gather all of the knowledge necessary to complete the build. Most of the components are easy to source, but unless you have them on hand, you’ll need put in a parts order for the crystal, the ATmega168, the SRAM chip, and the flash memory chip.

For those not familiar, FIGnition is an 8-bit computer with composite TV-out for a display and rudimentary input from the eight momentary push buttons.