The ability to play music in your car over a Bluetooth connection is very handy. You can typically just leave your phone’s Bluetooth module turned on and it will automatically pair to your car. Then all you have to do is load up a music player app and press play. You don’t have to worry about physically tethering your phone to the car every time you get in and out of the vehicle. Unfortunately Bluetooth is not a standard option in many cars, and it can be expensive to buy an aftermarket adapter.
[parkerlreed] built his own solution to this problem using a Raspberry Pi. He first installed arch Linux on his Pi. He also had to install pulseaudio and bluez, which is trivial if you use a package manager. He then modified some of the Linux configuration files to automatically bring the Pi’s Bluetooth adapter online once it is initialized by the kernel.
At the end of the boot sequence, the Pi is configured to automatically log in to a virtual console as [parkerlreed’s] user. The user’s bashrc file is then altered to start pulseaudio in daemon mode at the end of the login sequence. This allows the Pi to actually play the audio via the Pi’s sound card. The Pi’s stereo output jack is then plugged into the vehicle’s auxiliary input jack using a standard audio cable.
The Reddit post has all of the configuration details you would need to duplicate this setup. [parkerlreed] also includes some commands you will need to setup the initial pairing of the Raspberry Pi to your smart phone. Be sure to watch the video demonstration below. Continue reading “Raspberry Pi Bluetooth Receiver for your Car Stereo”
Cyborgs walk among us, but for the time being, it’s really only people with glasses, contact lenses, the occasional hearing aid and the infrequent prosthesis. As with all technology, these devices can be expanded into something they were not originally designed to do – in [Gertlex]’ case, the superpower of listening to music through his hearing aids. he gets a few strange looks from wearing a Bluetooth headset around his neck, but the power to turn his hearing aids ito what are effectively in-ear monitors is a great application of modified electronics.
[Gertlex] began with a Bluetooth headset, his hearing aid, a few resistors, some wire, a 3.5mm audio connector, and an absurdly expensive DAI cable. The DAI cable – Direct Audio Input – is a pseudo-standardized feature on many hearing aids. as its name implies, it allows the wearer of a hearing aid to pipe audio directly into their ear.
By cutting up one of these $50+ DAI cables, [Gertlex] was able to construct a DAI to 3.5mm adapter cable. From there, it was simply a matter of installing a 3.5mm socket on a Bluetooth headset.
It’s a brilliant build, with the most expensive component being the DAI connector itself. [Gertlex] has a few ideas for making these connectors himself – they’re really only three pins and some plastic – and we’re hoping he gets around to that soon.
How can you not be interested in a project that uses load cells, Bluetooth, a Raspberry Pi, and Twitter. Even for those of our readers without a cat, [Scott’s] tweeting litter box is worth the read.
Each aspect of this project can be re-purposed for almost any application. The inexpensive load cells, which available from eBay and other retailers, is used to sense when a cat is inside the litter box. Typically sensors like the load cell (that contain a strain gauge) this use a Wheatstone bridge, which is very important for maximizing the sensitivity of resistive sensor. The output then goes to a HX711, which is an ADC specifically built for load cells. A simple alternative would be using an instrumentation amplifier and the built-in ADC of the Arduino. Now, the magic happens. The weight reading is transmitted via an HC-06 Bluetooth module to a Raspberry Pi. Using a simple Perl script, the excreted weight, duration, and the cat’s resulting body weight is then tweeted!
Very nice work! This is a well thought out project that we could see being expanded to recognize the difference between multiple cats (or any other animal that goes inside).
Convention-goers have likely strolled past a number of Daleks: the aliens drive around the event space, spouting threats of extermination and occasionally slapping folks with a rotating eyestalk. [James Bruton] has been hard at work building this Wii-remote-controlled Dalek with his fellow hackers at the SoMakeIt Hackerspace (you may remember our write-up from earlier this year).
Most Dalek builds seat a driver inside the body at the helm of a salvaged electric wheelchair, where they plunk around using a joystick control and simmer in an increasingly potent aroma. This version started like most, with a wooden structure from plans sourced at Project Dalek. Inside, however, [James] and his crew have tapped into the wheelchair’s motor controller to feed it a PWM signal from an Arduino Shrimp, which is linked to a Raspi. The Pi receives a Bluetooth signal from a Wiimote, and, through their custom Python script, directs the Dalek with ease.
They’re still working on finishing the Dalek’s body, but they’re using some clever tactics to push onward: using a 3D-printer to solve some of the nuanced styling choices. They’ve uploaded a gallery with additional photos on Facebook, and you can watch them goofing around with their creation (losing their balance and nearly exterminating themselves) in a video after the break.
Continue reading “Wiimote Controlled Extermination: Dalek-Style”
If you’ve ever built anything with a microcontroller, some sort of sensor, and a connection to the outside world, you’re probably wondering how those places in China can pump out cheap electronics for a mere percentage of what it costs you to pull a DIY. It’s not just volume – it’s engineering; if something has Bluetooth, you find a Bluetooth module with a built-in microcontroller so you can write firmware to it.
The BC417 is the System on Chip found in the very popular BlueCore4-Ext Bluetooth module featuring 8Mbits of Flash (75% of which is used for Bluetooth related stuff), somewhere around 12 kB of RAM, with everything run in a virtual machine. [pfalcon] wrote an extremely experimental firmware for this device that allows anyone to create a wireless sensor node for peanuts. These devices are almost as cheap as a bare ATMega, so the possibilities are interesting, to say the least.
At this point, the hardest part of putting custom firmware on these devices is programming them. For that, [Elastic Sheep] comes to the rescue with a parallel port to SPI interface. There’s also a firmware dumper and some breakout boards available. These modules are pretty cheap, and the pitch isn’t too bad, so you might be able to etch your own boards should you want to experiment a little.
Thanks [Peter] for sending this in.
[Zenios] and [Raivis] are building a small balancing robot, and for communications to the outside world, they’re using a small, extremely cheap Bluetooth adapter. They figured uploading code to the microcontroller over Bluetooth would be a good idea, but their adapter, a cheap HC-06 module, had no way of resetting the microcontroller; it just provided Tx and Rx the serial port. They did notice a LED blinked when a device wasn’t connected to the adapter, so with a simple circuit they kludged a reset circuit where it wasn’t intended.
The small LED on the HC-06 module blinks when nothing is connected, and remains on when a connection is established. Figuring a new connection would be a good time to upload new code, the guys needed to design a circuit that would stay low when the LED was blinking, and switch to high when the LED was on.
A simple RC filter took care of the blinking LED, keeping the line low until a device connected. Bringing the logic level high when the LED stayed solid required digging through a part drawer, eventually finding an LM741 p differential amplifier.
After a few small changes to the bootloader, the guys had a reliable means of flashing new firmware without the need of programming adapters or wires draped over their workspace, all with a Bluetooth adapter that shouldn’t have this capability. Video below.
Continue reading “Programming Micros With Impossibly Cheap Bluetooth Adapters”
The perfect balance of simplicity and complexity have been struck with this automated artist. The Roboartist is a vector drawing robot project which [Niazangels], [Maxarjun], and [Ashwin] have been documenting for the last few days. The killer feature of the build is the ability to process what is seen through a webcam so that it may be sketched as ink on paper by the robotic arm.
The arm itself has four stages, and as you can see in the video below, remarkably little slop. The remaining slight wiggle is just enough to make the images seem as if they were not printed to perfection, and we like that effect!
Above is a still of Roboartist working on a portrait of [Heath Ledger] in his role as Joker from The Dark Knight. The image import feature was used for this. It runs a tweaked version of the Canny Edge Detector to determine where the pen strokes go. This is an alternative to capturing the subject through the webcam. For now MATLAB is part of the software chain, but future work seeks to upgrade to more Open Source tools. The hardware itself uses an Arduino Mega to take input via USB or Bluetooth and drives the quartet of servo motors accordingly.
Continue reading “Roboartist Draws What It Sees”