A Tweeting Litter Box

SmartLitterBox

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).

Wiimote Controlled Extermination: Dalek-Style

Dalek Build

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.

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Firmware For Cheap Bluetooth Modules

Ibluetoothf 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.

Programming Micros With Impossibly Cheap Bluetooth Adapters

tooth

[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.

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Roboartist Draws What It Sees

roboartist-vector-image-machine

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.

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Super Shoes Lead The Way

Super shoe insole with a red sneaker

Many of us spend so much time looking down at our phones that we miss the world all around us. [Dhairya] hopes to change that with Super Shoes, a pair of enhanced insoles that let your toes do the navigating while you enjoy the sights. Each insole has a Bluetooth radio and a microcontroller. Three coin cell vibrator motors act as an output device under the small toes, while a capacitive touch pad under the big toe handles input. Careful positioning of the electronics keeps the foam insoles flexible.

Using the shoes is as simple as walking around. Say you needed walking directions. You would set the destination on your smartphone. The shoes would then tie in to your smartphone’s GPS and maps application. From there, it’s simply a matter of following your toes. If the toes on your left foot vibrate, turn left. Vibration on the right foot indicates a right turn. When your destination is at hand, both feet will vibrate rapidly to celebrate.

[Dhairya] envisions a cloud service called ShoeCentral which will store a database of the user’s likes and dislikes. Based upon this data, ShoeCentral will guide the user to new restaurants or places they may like. All of this and hands free? Where do we sign up?

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Step Into the Ring with Fight Coach

box01

 

As MMA continues to grow in popularity, the competition is getting tougher. There’s always someone else out there who’s training harder and longer than you are. So how do you get the advantage over your competitors? More push-ups? Sit-ups? Eat more vegetables? What about installing custom 2 by 1 inch, 5 gram PCB’s armed with an ATmega32U4, a MPU-6050 6 axis accelerometer and an RN-41 Bluetooth module into each of your gloves? Now that’s what we’re talking about.

[Vincent] and [Jooyoung] of Cornell joined their classmates in turning out another cool piece of electrical engineering. Fight Coach records data from the fighter’s gloves so that it can not only be analyzed to improve performance, but also interact with the fighter in real-time.  Though not quite as immersive as some fighter training techniques we’ve seen, Fight Coach might just give a fighter a slight edge in the ring.

Fight Coach offers 3 modes of training: Defense mode, Damage mode and Free-Training mode. As usual with Cornell projects, all code, schematics and a wealth of information on the project is just a click away. And stick around after the break for a video demonstration of Fight Coach.

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