Embed With Elliot: Interrupts, The Ugly

October 2, 2015 by Elliot Williams 47 Comments

Welcome to part three of “Interrupts: The Good, the Bad, and the Ugly”. We’ve already professed our love for interrupts, showing how they are useful for solving multiple common microcontroller tasks with aplomb. That was surely Good. And then we dipped into some of the scheduling and priority problems that can crop up, especially if your interrupt service routines (ISRs) run for too long, or do more than they should. That was Bad, but we can combat those problems by writing lightweight ISRs.

This installment, for better or worse, uncovers our least favorite side effect of running interrupts on a small microcontroller, and that is that your assumptions about what your code is doing can be wrong, and sometimes with disastrous consequences. It’s gonna get Ugly

TL;DR: Once you’ve started changing variables from inside interrupts, you can no longer count on their values staying constant — you never know when the interrupt is going to strike! Murphy’s law says that it will hit at the worst times. The solution is to temporarily turn off interrupts for critical blocks of code, so that your own ISRs can’t pull the rug out from under your feet. (Sounds easy, but read on!)
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Ask Hackaday: I Love The Smell Of Burnt Hair In The Morning

October 1, 2015 by Brian Benchoff 200 Comments

At the end of the 19th century, [King Camp Gillette] had the idea of creating a disposable razor blade that didn’t need sharpening. There was one problem with this idea: metallurgy was not yet advanced enough to produce paper-thin carbon steel blades and sharpen them for a close shave. In 1901, [William Nickerson] solved this problem, and the age of disposable razors began.

The Skarp laser razor. Source — The Skarp laser razor

This Kickstarter would have you believe there is a new era of beard technology dawning. It’s a laser razor called Skarp, and it’s on track to become one of the most funded Kickstarters of all time. The only problem? Even with relatively good documentation on the Kickstarter campaign, a demo video, a patent, and an expert in the field of cosmetic lasers, only the creators can figure out how it works.

Instead of using technology that has been tried and tested for thousands of years, the Skarp uses a laser to shave hairs off, right at the surface of the skin. You need only look at a billboard for laser hair removal to realize this is possible, but building a laser razor is something that has eluded us for decades. This patent from 1986 at the very least demonstrates the beginnings of the idea – put a laser beam in a handheld package and plunge it into a beard. This patent from 2005 uses fiber optics to send a laser beam to a handheld razor. Like anything out of the sci-fi genre, a laser razor is a well-tread idea in the world of invention.

But Skarp thinks it has solved all of the problems which previously block lasers from finding a place in your medicine cabinet.

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New Part Day: Tiny, Tiny Bluetooth Chips

September 30, 2015 by Brian Benchoff 87 Comments

The future of tiny electronics is wearables, it seems, with companies coming out with tiny devices that are able to check your pulse, blood pressure, and temperature while relaying this data back to your phone over a Bluetooth connection. Intel has the Curie module, a small System on Chip (SoC) meant for wearables, and the STM32 inside the Fitbit is one of the smallest ARM microcontrollers you’ll ever find. Now there’s a new part available that’s smaller than anything else and has an integrated Bluetooth radio; just what you need when you need an Internet of Motes of Dust.

The Atmel BTLC1000 is a tiny SoC designed for wearables. The internals aren’t exceptional in and of themselves – it’s an ARM Cortex M0 running at 26 MHz. There’s a Bluetooth 4.1 radio inside this chip, and enough I/O, RAM, and ROM to connect to a few sensors and do a few interesting things. What makes this chip so exceptional is its size – a mere 2.262mm by 2.142mm. It’s a chip that can fit along the thickness of some PCBs.

To provide some perspective: the smallest ATtiny, the ‘tiny4/5/9/10 in an SOT23-6 package, is 2.90mm long. The smallest PICs are similarly sized, and both have a tiny amount of RAM and Flash space. The BTLC1000 is surprisingly capable, with 128kB each of RAM and ROM.

The future of wearable devices is smaller, faster and more capable devices, and with a tiny chip that can fit on the head of a pin, this is certainly an interesting chip for applications where performance can be traded for package size. If you’re ready to dive in with this chip the preliminary datasheets are now available.

Hackaday Prize Worldwide: Berlin, Germany

September 30, 2015 by Sophi Kravitz 3 Comments

Join the Hackaday Crew in Berlin this Saturday for a meetup!

This weekend in Berlin, Germany, there are at least two events happening and [Sophi], [Elliot] and [Bilke] are going to check them all out. The Vintage Computing Festival is one of the big events, and it looks like there will be lots of geeky magic to play with. This weekend is also Maker Faire Berlin where we’re looking forward to hanging out with our friends from Hackaday.io and we’re excited about meeting new people and projects.

Hackaday often throws a party after Maker Faire to celebrate all of our community projects and we’re doing it again Saturday night. We are co-hosting a party with the Vintage Computing Festival, on the same site as the festival, and all are welcome. We’ll have drinks and snacks, and the VCF has live music planned for the evening. This event is free, but we’d like you to RSVP so we know how many refreshments are needed.

Your first drink is on us, and naturally, if you bring a project,your second one is on us too! Please help spread the word by telling your friends, sharing on social media, and mobilizing all the people at your Hackerspace. See you on Saturday!

The 2015 Hackaday Prize is sponsored by:

3D Printing Has Evolved Two Filament Standards

September 29, 2015 by Brian Benchoff 56 Comments

We’re far beyond the heyday of the RepRap project, and the Hackaday tip line isn’t seeing multiple Kickstarters for 3D printers every week. In a way, this is a bit of a loss. The rapid evolution of the low-cost 3D printer seen in the first half of this decade will never be matched, and from now on we’ll only see incremental improvements instead of the revolutionary steps taken by the first Prusa, the first Printrbot, and even the Makerbot Replicator.

This doesn’t mean everything is standardized. There’s still enough room for arguing over deltas versus Cartesians, beds moving on the Y axis versus moving along the Z, and a host of other details that make the current crop of printers so diverse. One of these small arguments is especially interesting: the diameter of the filament. Today, you can get any type of plastic you want, in any color, in two sizes: 1.75 and 3mm. If you think about it, it’s bizarre. Why on Earth would filament manufacturers, hot end fabricators, and even printer manufacturers decide to support two different varieties of the same consumable? The answer is a mix of a historical choice, engineering tradeoffs, and an absolutely arbitrary consequence of what 3D printers actually do.

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Gathering The Hacking Community Of Zurich

September 29, 2015 by Sophi Kravitz 3 Comments

When my Swiss cousin-in-law sent us her wedding invitation, I didn’t immediately think I’d get to see Hackaday.io user [antti.lukats‘] tiny FPGA projects as part of the deal. I’m really glad that I came to Switzerland for the wedding, and also got to be a part of an awesome meetup in Zurich’s Fablab. [Antti], who was at the meetup, is pictured above holding a small tube full of FPGAs, he’s a Hackaday Prize Best Product finalist with FPGA project DIPSY.

As is becoming the norm for Hackaday meetups, we ask people to bring projects. We then count all the people who want to present something and squeeze all the presentations into just about 90 minutes. Before and after the lightening talks, there’s always plenty of time to walk around and see individual projects, meet people and of course eat and drink.

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Hackaday Links: September 27, 2015

September 27, 2015 by Brian Benchoff 13 Comments

Many moons ago, [Joe Grand] built an adapter that turns Atari 2600 joysticks to USB controllers. Now it’s open source.

Hackaday Overlord [Matt] is holding an SMT and BGA soldering workshop in San Francisco on October 4th. Teaching BGA soldering? Yes! He made a board where the BGA balls are connected to LEDs. Very, very clever.

Our ‘ol friend [Jeremey Cook] built a strandbeest out of MDF. It’s huge, heavy, about the size of a small car, and it doesn’t work. [Jeremy] has built beests before, but these were relatively small. The big MDF beest is having some problems with friction, and a tendency to shear along the joints. If anyone wants to fix this beest, give [Jeremy] a ring.

Everyone loves the Teensy, and [Paul] has released his latest design iteration. The Teensy 3.2 isn’t that much different from the Teensy 3.1; the bootloader has changed and now USB D+ and D- lines are broken out. Other than that, it’s just the latest iteration of the popular Teensy platform.

The DyIO is a pretty neat robotics controller, a semifinalist for the Hackaday Prize, and now a Kickstarter. The big win of the Kickstarter is an electronics board (with WiFi) that is able to control 24 servos for all your robotics needs.

[pighixxx] does illustrations of pinouts for popular electronics platforms. Everyone needs a hobby, I guess. He recently put together an illustration of the ESP8266. Neat stuff is hidden deep in this site.

You would not believe how much engineering goes into making snake oil. And then you need to do certifications!

[David] identified a problem, created a solution, got a patent, and is now manufacturing a product. The only problem is the name.