Video: Working with the 3pi robot’s line sensors

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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Weekly Roundup 11/12/11

In case you missed them the first time around, here are our most popular posts from the past week:

In the #1 spot, we had a post about a tri-color laser projector that really is a well-done project. This projector sweeps the lasers around in vector mode using a pair or mirror galvanometers so would be perfect for playing asteroids in vivid full color!

In at #2 is a post about a PVC pipe gun that can shoot AA batteries at 600 batteries per minute!

Next up we have a post about the US military finding that due to Chinese counterfeit electronics, some of its weapon systems are defective. This has become a more serious issue in recent years. It has effected hackers too as shown in this Sparkfun post from last year.

After that, we had a post about a novel and somewhat scary way to post bulletins on a board without using tacks. How do they do that? By carefully using 20,000 Volts! Yikes. We’ll stick to tape next time we run out of tacks thank you very much.

Finally, we have one about a spot welder built out of some super capacitors and carbon rods. This one probably produces equally large sparks where it is welding and at the triggering mechanism!

Weekly roundup 11/5/11

In case you missed them the first time, here are this week’s most popular posts:

Our most popular post is about an octocopter that is big enough to hover a person who is perched perilously in the center of an angry array of blades that are counting on Murphy’s law for their chance to taste a little human blood.

Next up is a post about an interesting clock made out of Legos that uses a mechanism similar to the one inside of a combination lock to display the time.

In third place is a post about [Lizzie] and her ‘ball of dub’ that is hard to explain but interesting to listen to.

Next we have a post about how some Occupy Wall Street protesters are generating electricity despite having their generators confiscated. This one is about the hack folks, not the protest. Let’s try to keep the comments civil…

Finally, we have one about a new circuit board put out by the folks who brought us the Beagleboard. This one is called the Beaglebone and it is packing some serious firepower for just $89! We can’t wait to see what our readers come up with these puppies (pun intended)!

Video: Analog to Digital Conversion on the ATmega328p

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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Weekly Roundup 10/29/11

In case you missed them the first time, here are the most popular posts from this week:

Our most popular post this week was about how to use HTML5 to display sensor data. This is a pretty interesting demo of the new web technology.

Next up is a post about an animatronic zombie that can crawl around via remote control. It is surprisingly maneuverable and would definitely be creepy crawling towards you in the dark dark middle of the night.

After that is a post where our own [Kevin Dady] created a new charger for a cell phone that he recently acquired. This is a pretty comprehensive tutorial that could be of use to others who may have misplaced their charger and have some spare parts lying around.

Next we have a post about a new technology that has been created that lets you render objects into photos that have been previously taken.

Finally, there is a post about a research project that uses a Microsoft surface and a whole mess of proximity sensors to detect where people are located and which hand they are touching the surface with.

Video: PWM on the ATmega328p

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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Weekly Roundup 10/22/11

In case you missed them the first time, here are our most popular posts from the past week.

Our most popular post of the week was about a ball that has a matrix of 256 LEDs encrusted onto its surface, allowing all sorts of patterns to be displayed.

Next up is a post about the vibrator shield for the Arduino. If you must mix sex and nerdy things, this is one route to happiness. This post is safe for work but the links may not be.

After that we had a post about a novel way to take panoramic pictures. In this post, you will see a ball that has an array of 36 cameras embedded into it. If you throw it into the air, it will take a picture at the apex of its travel.

In fourth place, we have a post describing how you can add an external GPU to your laptop. If you only have a laptop and are looking to play with the latest and greatest graphics, this is one route that you could take.

Finally, if you like things that glow, this one is for you. This post links to a video showing you how to make luminol using household chemicals.


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