Video: Working With The 3pi Robot’s Line Sensors

November 12, 2011 by Jack Buffington 4 Comments

This week, we are serving up part five in our series where we are using the Pololu 3pi robot as a fancy development board for the ATmega328p processor. This week we are taking a quick break from working with the perpherals specific to the processor and will show how to work with the 3pi’s line sensors. A quick look at the schematic for the 3pi might lead you to think that you should be reading the line sensors with the A2D peripheral. Even though they are wired to the A2D pins, they need to be read digitally. In the video, [Jack] will show how to read raw values from the sensors and then how to calibrate the results so that you can get a nice clean 8-bit value representing what the sensors are seeing. Of course, that would happen under normal circumstances. Murphy had his way in this video and it turned out that our studio lighting was interfering a bit with the sensor readings when we were shooting so we didn’t get as good of a calibration as we would have liked when we shot.

Video is after the break.

In case you have missed the previous videos here are some links:

Part 1: Setting up the development environment
Part 2: Basic I/O
Part 3: Pulse Width Modulation
Part 4: Analog to Digital conversion

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Ghostly Images Appear Thanks To Projections On Fog

November 12, 2011 by Mike Szczys 28 Comments

This wire-frame cube appears to be floating in mid-air because it actually is. This is a project which [Tom] calls a Laminar Flow Fog Screen. He built a device that puts out a faint amount of fog, which the intense light from a projector is able to illuminate. The real trick here is to get a uniformed fog wall, which is where the laminar part comes in. Laminar Flow is a phenomenon where fluids flow in a perfectly parallel stream, not allowing errant portions to introduce turbulence. This is a favorite trick with water.

[Tom’s] fog screen starts off with a PC fan to move the air. This airflow is smoothed and guided by a combination of a sponge, and multiple drinking straws. This apparatus is responsible for establishing the laminar flow, as the air picks up fog from an ultrasonic fogger along the way.

The only real problem here is that you want the projector shooting off into infinity. Otherwise, the projection goes right through the fog and displays on the wall, ruining the effect. Outdoor applications are great for this, as long as there’s no air movement to mess with your carefully established fog screen.

You can find a short test clip embedded after the break but there are other videos at the link above.

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Big Head Costume Would Make Max Headroom Jealous

November 9, 2011 by Mike Nathan 21 Comments

big-head-halloween

[Dan Rosenfeld] does a lot of thinking in his spare time, and one thing he returns to pretty often is videoconferencing. He’s often wondered why it hasn’t caught on enough to become a ubiquitous piece of technology, and his examination of the topic in regards to eye contact and spatial awareness inspired him to create a very unique Halloween costume.

His “Big Head” costume consists of a front-mounted 24” LCD panel that displays the wearer’s face in real time. Inside the large headpiece [Dan] installed a microphone, another LCD screen, a half silvered mirror, and a video camera – not to mention all of the power-related goodies required to keep it running. While the main LCD displays his face, the internal monitor is fed by an externally mounted camera that shows him everything going on outside the box. This image is reflected off the half silvered mirror, allowing him to gaze directly at the camera, while also seeing what’s going on in front of him.

As you can see in the video below, the effect is pretty cool, and devoid of the ‘disconnected’ look most people have when talking to others via a camera and computer screen.

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Video: Analog To Digital Conversion On The ATmega328p

November 3, 2011 by Jack Buffington 6 Comments

In this week’s video, we continue on where we left off last week with another in our series of videos where we discuss how to program for the ATmega328p processor. This week, [Jack] takes a look at the analog to digital converter and takes us through how to set things up and then how to perform a conversion using the potentiometer on the 3pi as the analog source. Playing with potentiometers isn’t the most interesting thing in the world, but after watching this video, you will be able to do things like take light readings using a cadmium sulfide cell, read the weight applied to a sensor, calculate the temperature from a resistor and a thermistor, or interface with an analog gyroscope.

If you have missed our previous videos, here are some links:
Part 1: Setting up the development environment
Part 2: Basic I/O
Part 3: Pulse Width Modulation

Stay tuned for next week’s* video where we will take a look at how to interface with the 3pi’s line sensors.

Video is after the break…

* HAD is in the process of moving our secret headquarters so next week’s video may come some time later than next week.

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Interactive Digital Fireplace Is Great For Those Chilly Winter Evenings

November 3, 2011 by Mike Nathan 14 Comments

video-fireplace

We’ve all seen them – those fireplace DVDs that seem to pop up on grocery store endcaps and get traded in white elephant gift exchanges. If you don’t happen to have a fireplace in your home they might make a reasonable solution, but [Nick] from the Gadget Gangster thought it would be far better if you could create your own interactive digital fireplace instead.

Using the Gadget Gangster Propeller USB platform and ProtoPlus board, his fireplace merges various video segments together based on user input, and plays them on any TV that comes equipped with RCA jacks. The process is fairly straightforward, and involves wiring up switches along with audio and video output to the Propeller board via the ProtoPlus board. The remainder of the work is done using software, requiring the user to select and encode video segments for storage on an SD card. [Nick] does however provide a whole set of clips for download, should you want to take the quicker route.

After encoding and categorizing the video clips to coincide with the “stoke” and “add wood” user input buttons, the Propeller does the rest of the work, randomly selecting clips from the appropriate category when requested.

The result is admittedly a bit Lo-Fi, though we thinks it’s cool and prefer to call it “retro” instead. It might not be a Hi-Def fireplace recording, but it’s far nicer to snuggle up to a hand made fireplace rather than a DVD you picked up as an afterthought.

Continue reading to see a quick demo video of the digital fireplace in action.

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Synthesizing Sound With A Light Sensitive Pen And CRT Television

October 29, 2011 by Mike Szczys 7 Comments

Here’s the latest project from [Niklas Roy’s] workshop. Lumenoise is an audio synthesizer controlled by drawing with a light-sensitive pen on a CRT television.

The pen is a self-contained module which connects to the TV via audio and composite video RCA plugs. Inside the clear pen housing you’ll find a microcontroller which generates the audio and video. The business end of the pen contains a phototransistor which lets the ATmega8 take a reading from the video screen. Since the chip is generating that video signal, it’s possible to calculate the pen tip’s position on the screen and modulate the sound output based on that data. You can watch a recording of the results in the video after the break.

This is a very simple circuit to build, and [Niklas] makes the point that most of us have a CRT hanging around in a dark corner somewhere. We think this would be a fantastic soldering project to do with the kids, and that this would be right at home as a children’s museum piece because of the wow factor involved in playing around with it.

We can really tell from this and some of his past projects that [Niklas] just loves the 8-bit audio.

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Video: PWM On The ATmega328p

October 27, 2011 by Jack Buffington 5 Comments

This week we continue on with another video in our series about how to program for the ATmega328p processor using C. The ATmega328p is at the heart of many Arduino boards. If you have been using them but want to add some more horsepower to your projects, this series of videos is for you. In this video, [Jack] talks about various types of pulse width modulation (PWM). You can use PWM to control the speed of a motor, the brightness of a LED, or to generate analog waveforms. [Jack] shows how to set up the processor to do locked anti-phase PWM to drive the wheels of the 3pi robot and then demos a short program that shows the code in action.

If you missed the previous posts in this series and would like to check them out…
Intro and how to set up the development environment : Click Here
Working with I/O pins: Click Here

Video is after the break…
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