Getting started with OpenCV

[Eric Gregori] sent in an article he wrote for EETimes to introduce the concepts behind computer vision to the masses. As a nice little bonus, [Eric] included a VMware image containing Ubuntu and all the packages and examples necessary to write your own OpenCV apps.

There’s a ton of awesome stuff you can do with computer vision – from automated sentries to keep squirrels away, a kitchen that will tell you when to do the dishes, and automating blindness by mounting a laser on a face tracker, there’s a lot of unexplored territory in the area of computer vision.

Included in [Eric]‘s VM image are a motion and line detection example app, an ‘optical flow’ example, and a face detection example. There’s enough here to make a few very interesting projects, so hopefully, [Eric]‘s VM image and examples will get your next CV project up and running quickly.

Get neck-deep into ZigBee

Here’s a bulky tutorial that will round-out your understanding of ZigBee wireless communications (translated). The protocol is great for hobby electronics projects because it uses low-power short range wireless devices to build a mesh network. The guide covers both hardware and software, but also takes the time to explain what that hardware is doing in the background.

As you can see, several different renditions of an XBee module are used as examples. They pretty much all rely on a series of SparkFun breakout boards that each serve different purposes. Once you’ve acquired these modules, there’s a fair number of choices needed to configure them to play nicely with each other. We read most of the tutorial (we’ll save the rest for later enjoyment) and had no problem following along even without owning the hardware or being able to use the interface as we learned.

Whenever we cover XBee modules we always like to mention that it’s quite easy to use these for remote sensors with no additional microcontroller needed.

Learning to use the V-USB (AVR USB firmware) library

The V-USB library is a pretty handy piece of code that lets you add USB connectivity to ATtiny microcontrollers (it was previously named tinyUSB). But if you’ve ever looked into adding the library to your own projects you may have been stymied by the complexity of the code. There are many examples, but there’s a lack of a concise quick-start for the uninitiated. [Joonas Pihlajamaa] has been working to correct that shortfall with his four-part V-USB tutorial series. It’s not for the absolute newbie; you should already be comfortable working with AVR chips but that’s the only real prerequisite we can see.

He starts the series with a look into the hardware considerations. USB provides a 5V power rail but the data lines expect 3.3V logic so this must be accounted for. With the test rig built on a breadboard he moves on to pick apart the code, covering various user-defined variables that you’ll need to set based on your project’s needs. We’re going to keep this on the back burner and hopefully the Troll Sniffing Rat will get a makeover (although we must say comments have been a lot nicer as of late… keep it up!).

We’ve embedded links to all four tutorial parts after the break.

[Read more...]

So you wanna learn FPGAs…

FPGAs are the bee’s knees. Instead of programming a chip by telling it what to do, FPGAs allow you to tell a chip what to be. Like everything though, a new skill set is needed to fully exploit the power of FPGAs. [Mike Field] decided to give back to the internet community at large and put up a crash course in FPGA design.

Right now, [Mike] has a couple of modules up that include subjects like binary math, busses, counting, and of course setting up the FPGA hardware. The recommended hardware is the Papilio One, although the Digilent Nexys2 is what [Mike] has been using so far.

We’ve seen a ton of awesome stuff that uses FPGAs, like the emulated Mac Plus, breaking HDCP, and an Ocarina of Time. [Mike]‘s tutorials look like a great starting point for some FPGA work. [Mike] is also looking for some feedback on his tutorials, so if you’ve got an idea of what he should cover be sure to drop him a line.

EDIT: The server was running on an FPGA and we can’t find a cache anywhere. If you’ve found a mirror, send a message. Apparently Amazon’s EC2 runs on an FPGA.

An introduction to stepper motors

If you’ve been reading Hack a Day for long enough, you know about our infatuation with stepper motors. These precious little devices put the oomph into our CNC routers, 3D printers, robots, and other miscellaneous projects. Steppers aren’t your run-of-the-mill motors, though. [Steaky] posted a great introduction to stepper motors that lets you hit the ground running building any moving project you could imagine.

Apart from identifying a stepper and figuring out if it works, [Steaky] goes over how to make these motors turn. The theory behind an H-bridge is easy enough, but theory isn’t something often presented in schematics or stepper driver datasheets.

We’ve pulled more than our fair share of steppers from flatbed scanners and old printers. There’s nothing wrong with scavenging old parts, and whether you’re making a robot band to play your kid’s birthday party, robochess, or one of the many 3D printers or CNC machines, there’s going to be a stepper motor in your future.

Beginner concepts: We’re gonna let you finish, but first this tutorial on Arduino interrupts

OK, year-old pop culture references aside [Kyle] dropped us a line to show us his tutorial on using interrupts with your Arduino. Given the single core nature of your average Arduino’s AVR you pretty much have two choices for monitoring occasional un-timed inputs: Either check an input at an interval (which risks missing the signal entirely) or set up an interrupt to pause the chip’s normal operation. Obviously working with interrupts saves you tons of clock cycles since you are not polling a pin over and over. [Kyle] plans on a follow up tutorial to cover timer based interrupts, which can come in handy when generating frequencies and stuff.

Looking for more Arduino Basics? How about Basic on an Arduino. Check out our other beginner concepts posts as well if you need to work on your fundamentals.

Video: Eagle CAD Layout

This week’s video is the last in a series of videos where we show how to use Eagle CAD. Today we will look a the Layout portion of the program and will create a circuit board from the schematic that we created previously. We start by creating a layout file and then moving all of the parts to appropriate places on the circuit board. After that, [Jack] shows how to route the traces. Along the way, he talks about the tools that he is using and various ways to use them. The end result is a prototyping board for the PIC18F44J11.

Like the others, this video is fairly long at 29 minutes, so make sure to have some time dedicated towards watching it if you do.

In next week’s video, we will be showing this board as it arrived to us from a manufacturer and will do a tutorial on how to solder.

If you have missed our previous videos, you can find them here:

Schematic part I
Schematic and Custom part creation
CAM Processor

We have also created many supplemental videos explaining how to use many of the tools in the tool palettes. You can find them on our Youtube channel:

Check out the video after the break!
[Read more...]

Follow

Get every new post delivered to your Inbox.

Join 92,288 other followers