Curated

76 Articles

Hackaday’s finest original content articles curated by the Hackaday editors

What Could Go Wrong: SPI

July 1, 2016 by 58 Comments

Serial Peripheral Interface (SPI) is not really a protocol, but more of a general idea. It’s the bare-minimum way to transfer a lot of data between two chips as quickly as possible, and for that reason alone, it’s one of my favorites. But that doesn’t mean that everything is hugs and daffodils. Even despite SPI’s simplicity, there are still a few ways that things can go wrong.

In the previous article in this series, inspired by actual reader questions, I looked into troubleshooting asynchronous serial connections. Now that you’ve got that working, it’s time to step up to debugging your SPI bus! After a brief overview of the system, we’ll get into how to diagnose SPI, and how to fix it.

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HALT In The Name Of Testing

July 1, 2016 by 16 Comments

“Did I forget something?” It’s that nagging feeling every engineer has when their project is about to be deployed – it may be a product about to be ramped into production, a low volume product, or even a one off like a microsatellite. If you have the time and a few prototypes to spare though, there are ways to alleviate these worries. The key is a test method which has been used in aerospace, military, and other industries for years – Highly Accelerated Life Testing (HALT).

How to HALT

The idea behind HALT testing can be summed up in a couple of sentences:

  • Beat your product to death.
  • Figure out what broke.
  • Fix it, and fix the design.
  • Repeat.

Sounds barbaric, and in many cases it is. HALT testing is often associated with giant test chambers which are literally designed to torture anything inside them. Liquid nitrogen shock cools the chamber as low as -100°C. The Device Under Test (DUT) can soak at that temperature for hours. Powerful heaters then blast the chamber, causing temperature rises of up to 90°C per minute, topping off at up to 200°C. Pneumatic hammers beat on the chamber table causing vibrations at up to 90 Grms and 10 KHz. Corrosive sprays simulate years of rain and humidity. These chambers are literally hell on earth for any device unlucky enough to be placed inside them. It’s easy to see why this sort of testing is often referred to as “Shake and Bake”.

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Makerspace North, From Empty Warehouse To Maker Magnet

June 30, 2016 by 5 Comments

Makerspace North is unique out of the 5 makerspaces in the Ottawa, Canada area in that it started life as an empty 10,000 square foot warehouse with adjoining office spaces and large open rooms, and has let the community fill it, resulting in it having become a major hub for makers to mix in all sorts of ways, some unexpected.

Many makerspaces are run by an organization that provides tools that groups or individuals use, along with qualification courses for select tools. Makerspace North, on the other hand, provides the space and lets the community provide the maker component. The result is a variety of large scale events from indoor drone flying and various types of maker faire style days, to craft shows, garage sales, and even concerts. Smaller meet-ups, most often open to anyone, are held by such groups as the Ottawa Robotics Club and the Ottawa Electronics Club as well as some more general ones. Courses offered by the community are also as varied.

This also means that the owners of Makerspace North don’t provide tools for people to use, but instead provide dedicated rental space. That doesn’t mean there aren’t tools — it means that Makerspace North encompasses a microcosm of various renters who fill out the task of things like tool rental. This is just one example of how the community has embraced the unique approach. Let’s take a closer look at that and a few other novelties of this system.

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Tools Of The Trade – Inspection

June 29, 2016 by 15 Comments

In the last episode, we put our circuit boards through the reflow process. Unfortunately, it’s not 100% accurate, and there are often problems that can occur that need to be detected and fixed. That’s what the inspection step is for. One could insert an inspection step after paste, after placement, and after reflow, but the first two are icing on the cake — the phase where most mistakes can be caught is after reflow.

There are a number of problems typical with a surface mount reflow process: Continue reading “Tools Of The Trade – Inspection” →

Taming The Beast: Pro-Tips For Designing A Safe Homebrew Laser Cutter

June 29, 2016 by 51 Comments

Homebrew laser cutters are nifty devices, but scorching your pals, burning the house down, or smelling up the neighborhood isn’t anyone’s idea of a great time. Lets face it. A 60-watt laser that can cut plastics offers far more trouble than even the crankiest 3D-printers (unless, of course, our 3D printed spaghetti comes to life and decides to terrorize the neighborhood). Sure, a laser’s focused beam is usually pointed in the right direction while cutting, but even an unfocused beam that reflects off a shiny material can start fires. What’s more, since most materials burn, rather than simply melt, a host of awful fumes spew from every cut.

Despite the danger, the temptation to build one is irresistible. With tubes, power supplies, and water coolers now in abundance from overseas re-sellers, the parts are just a PayPal-push away from landing on our doorsteps. We’ve also seen a host of exciting builds come together on the dining room table. Our table could be riddled with laser parts too! After combing through countless laser build logs, I’ve yet to encounter the definitive guide that tells us how to take the proper first steps forward in keeping ourselves safe while building our own laser cutter. Perhaps that knowledge is implicit to the community, scattered on forums; or perhaps it’s learned by each brave designer on their own from one-too-many close calls. Neither of these options seems fair to the laser newb, so I decided to lay down the law here.

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Serially, Are You Syncing Or Asyncing?

June 28, 2016 by 25 Comments

I know you’ve heard of both synchronous and asynchronous communications. But do you really know the differences between the two?

Serial communication was used long before computers existed. A predecessor is the telegraph system using Morse Code, one of the first digital modes of communication. Another predecessor is the teletype, which set standards that are still used today in your Arduino or Raspberry Pi.

All you need is two wires for serial communications, which makes it simple and relatively robust. One wire is ground and the other the signal. By interrupting the power with predefined patterns, information can be transferred over both short and long distances. The challenge is receiving the patterns correctly and quickly enough to be useful.

I was a bit surprised to find out the serial port on the Arduino Uno’s ATmega328P microcontroller is a Universal Synchronous Asynchronous Transmitter Receiver (USART). I’d assumed it was only a UART (same name, just leave out synchronous) probably because my first work with serial communications was with the venerable Intel 8251 “Programmable Communication Interface”, a UART, and I didn’t expect the microcontroller to be more advanced. Silly me. Later I worked with the Zilog 8530 Serial Controller Chip, a USART, the term I’ll use for both device types.

All these devices function in the same way. You send a byte by loading it into a register and it is shifted out one bit at a time on the transmit (TX) line as pulses. The receiver accepts the pulses on a receive (RX) input and shifts them into a register, which is then read by the system. The transmitter’s job is pretty easy it just shifts out the bits at a known clock rate. The receiver’s task is more complex because it needs to know when to sample the incoming signal. How it does this is the difference between asynchronous and synchronous communications.

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Taking Killer Robots Seriously

June 27, 2016 by 61 Comments

Killer robots are a mainstay of science fiction. But unlike teleportation and flying cars, they are something that we are likely to see within our lifetime. The only thing that’s stopping countries like the USA, South Korea, the UK, or France from deploying autonomous killing machine in the very near term is that they’re likely to be illegal under current international humanitarian law (IHL) — the rules of war.

But if you just sighed in relief that the fate of humanity is safe, think again. The reason that autonomous killing machines are illegal is essentially a technicality, and worse, it’s a technicality that’s based on the current state of technology. The short version of the story, as it stands right now, is that the only thing making autonomous robotic killing weapons illegal is that it’s difficult for a robot to tell a friend from an enemy. When technology catches up with human judgement, all bets are off.

Think I’m insane? The United Nations Office at Geneva (UNOG), the folks who bring you the rules of warfare, started up a working group on killer robots three years ago, and the report from their 2016 meeting just came out. Now’s as good a time as any to start taking killer robots seriously.

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