Embed With Elliot: Practical State Machines

September 4, 2015 by Elliot Williams 41 Comments

Raindrops on roses, and whiskers on kittens. They’re ok, but state machines are absolutely on our short list of favorite things.

There are probably as many ways to implement a state machine as there are programmers. These range from the terribly complex, one-size-fits-all frameworks down to simply writing a single switch...case block. The frameworks end up being a little bit of a black box, especially if you’re just starting out, while the switch...case versions are very easy to grok, but they don’t really help you write clear, structured code.

In this extra-long edition of Embed with Elliot, we’ll try to bridge the middle ground, demonstrating a couple of state machines with an emphasis on practical coding. We’ll work through a couple of examples of the different ways that they can be implemented in code. Along the way, we’ll Goldilocks solution for a particular application I had, controlling a popcorn popper that had been hacked into a coffee roaster. Hope you enjoy.

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How To Build Anything Using Delrin And A Laser Cutter

September 3, 2015 by Sonya Vasquez 58 Comments

Need a simple fab process to go from a humble vector graphic to a final part — in a matter of minutes? The CO₂ laser cutter might be the right choice. As these tools open themselves up to widespread use through hackerspaces, I decided to give Delrin some well-deserved time under the spotlight.

The laser cutter yet-again proves itself a formidable tool with the construction of GameCube-Bot V2

This guide is a brief collection of tips and techniques that I’ve either learned from others or discovered on my own over the last couple years working with laser-cut Delrin (a.k.a Acetal) for functional prototypes. I hope this guide serves you well as we keep exploring the limits of the material.

As a disclaimer, keep in mind that in no way are these techniques unique or limited to Delrin. Many are not only years old but also common practice in either engineering design or the local machine shop. This article simply highlights the techniques shown here that perform both repeatably and predictably with Delrin and a couple hand-tools, and I hope to share them with a growing audience of laser cutter enthusiasts.

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Learn 3D Modeling In Your Browser

September 3, 2015 by Al Williams 41 Comments

If you have a 3D printer, it is a good bet you’ve at least seen or heard of Tinkercad. There’s pros and cons to doing your design in a Web browser, but Tinkercad is very easy to use and great for making simple objects. However, there are other 3D object designers you can use in your browser, too. Tinkercad is just the one that everyone seems to know about.

I won’t talk much about Tinkercad, but if you haven’t tried it, it is well worth a look. It has a simple system of drawing things and holes. When you merge holes with things you can make lots of shapes. The alignment tools are good, and since Autodesk acquired them (part of its 123d app suite), it isn’t likely they will go under any time soon (which, as you may remember, almost happened).

If you are designing some great new secret invention you may shy away from cloud-based design programs. But if you are printing out key chains with your coworker’s cat’s name on it, do you really care? Most of these cloud-based programs will work from any computer so you can quickly do a design in a coffee shop and then go home and print it.

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Why IoT Will Fail (and How To Save It)

September 3, 2015 by Al Williams 76 Comments

Buzzword technology has two possible fates: they fail and disappear or they succeed and disappear. Remember at one time “multimedia” and “networking” were buzzwords. They succeeded and now they’ve vanished into ubiquity. Of course, there are plenty of failed buzzwords (like telecosm) that you probably don’t even remember. They just vanished into obscurity.

Unless you’ve been living under the CNC mill in your local hackerspace, you’ve probably heard or read about the “Internet of Things” (IoT). Companies big and small have realized that getting in early on The Next Big Thing is good for share prices and, right now, IoT is where everyone is trying to make a play.

There’s two things I’d observe, though: First, IoT is far from new. Connecting embedded systems to the Internet is old hat (I even wrote a book called Embedded Internet Design way back in 2003). Second, the way it is going, IoT–in its current incarnation–is doomed.

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How CMOS Works: Some Final Words About CMOS

September 2, 2015 by Bil Herd 18 Comments

Finishing up on the topic of CMOS bus logic I am going to show a couple of families with unique properties that may come in handy one day.

High Voltage Tolerant Family: AHC/AHCT

AHCT w/o high side diode — Note the missing diode to VDD

First up is a CMOS logic family AHC/AHCT that has one of the protection diodes on the input removed. This allows a 5V input voltage to be applied to a device powered by 3.3V so that I don’t have to add a gate just for the translation. Any time I can translate and do it without any additional gate delays I am a happy engineer.

Of course the example above works in a single direction and bidirectional does start to get more complicated. Using a bidirectional buffer such as a 74AHCT245 will work for TTL translation when going from 3.3V back to 5V providing there is a direction control signal present.

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V2V: A Safer Commute With Cars Sharing Status Updates

September 2, 2015 by Brian Benchoff 43 Comments

Every year, more than 30,000 people are killed in motor vehicle accidents in the US, and many many more are injured. Humans, in general, aren’t great drivers. Until dependable self-driving cars make their way into garages and driveways across the country, there is still a great amount of work that can be done to improve the safety of automobiles, and the best hope on the horizon is Vehicle to Vehicle communications (V2V). We keep hearing this technology mentioned in news stories, but the underlying technology is almost never discussed. So I decided to take a look at what hardware we can expect in early V2V, and the features you can expect to see when your car begins to build a social network with the others around it.

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The Year Of The Car Hacks

September 1, 2015 by Eric Evenchick 61 Comments

With the summer’s big security conferences over, now is a good time to take a look back on automotive security. With talks about attacks on Chrysler, GM and Tesla, and a whole new Car Hacking village at DEF CON, it’s becoming clear that autosec is a theme that isn’t going away.

Up until this year, the main theme of autosec has been the in-vehicle network. This is the connection between the controllers that run your engine, pulse your anti-lock brakes, fire your airbags, and play your tunes. In most vehicles, they communicate over a protocol called Controller Area Network (CAN).

An early paper on this research [PDF] was published back in 2010 by The Center for Automotive Embedded Systems Security,a joint research effort between University of California San Diego and the University of Washington. They showed a number of vulnerabilities that could be exploited with physical access to a vehicle’s networks.

A number of talks were given on in-vehicle network security, which revealed a common theme: access to the internal network gives control of the vehicle. We even had a series about it here on Hackaday.

The response from the automotive industry was a collective “yeah, we already knew that.” These networks were never designed to be secure, but focused on providing reliable, real-time data transfer between controllers. With data transfer as the main design goal, it was inevitable there would be a few interesting exploits.

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