Hacking Together A Temperature Sensor For Boiling Milk

Ever have trouble justifying your hacking to anyone from another generation? [Domen] presented his mother with a custom-made device that monitors the milk temperature as it boils on the stove, preventing boil-over. And he made the device robust, simple to use, and foolproof. To his mom, it must look like he’s a wizard — able to conjure up home electronics out of solder smoke and some plywood.

Of course, we know better. Inside his gadget is a simple temperature sensor, an ATtiny841, a very nice home-made PCB, a buzzer, an LCD, and some pushbuttons. [Domen] rubbed together a few pre-existing libraries, and had a working prototype inside a nice wooden box on the quick. It’s a simple hack, but imagine how this must look to a muggle. For the detailed incantations, check out [Domen]’s GitHub for the project.

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Getting IEC Standards For Free

The International Electrotechnical Commission (IEC) is an international body that issues standards on a wide range of electronics-related topics. How wide? Their mandate seems to span rules for household product safety to the specification of safety logic assemblies in nuclear power plants. Want to know how to electrically measure sound loudness? Test methods for digital door lock systems? Or maybe you’re interested in safety interlock systems for laser processing machines. There’s an IEC standard for that too.

Unfortunately, this information is kept behind a paywall. OK, it’s a lot more like a pay fortress. They really, really don’t want you accessing their documents without first coughing up. This is a shame.

The IEC doesn’t just make the standards in a vacuum, however. Before the scribes touch their chisels to the stone tablets, there are draft versions of the standards that are open for public comment by those knowledgeable in the field. And by “those knowledgeable”, we mean you, dear hacker. Head on over to the public commenting page, sign up, and you’ve got free access to every document that’s currently up for discussion.

Now, it does look like the IEC doesn’t want you sharing these PDFs around — they watermark them with your username and threaten all sorts of things if you use them for anything other than commenting purposes — so don’t go abusing the system. But on the other hand, if you are a private individual who knows a thing or two about a thing or two, we think you’re entirely right to look over their shoulders. Let us know in the comments if you find any gems.

They’ve even got a weekly update feature (in the registration pages) that’ll keep you up to date. And who knows, maybe your two cents, submitted to your country’s chapter of the IEC, will influence future international standards.

Thanks to [Johann] for the great tip!

Ask Hackaday: Computing Square Roots On FPGA?

Hackaday reader [nats.fr] wrote in with some code from a project that resizes a video stream on the fly using an FPGA. Doing this right means undoing whatever gamma correction has been applied to the original stream, resizing, and then re-applying the gamma. Making life simpler, [nats.fr] settled on a gamma of two, which means taking a bunch of square roots, which isn’t fast on an FPGA.

[nats]’s algorithm is pretty neat: it uses a first-stage lookup to figure out in which broad range the value lies, and then one step of Hero’s algorithm to refine from there. (We think this is equivalent to saying he does a piecewise linear interpolation, but we’re not 100% sure.) Anyway, it works decently.

Of course, when you start looking into the abyss that is special function calculation, you risk falling in. Wikipedia lists more methods of calculating square roots than we have fingers. One of them, CORDIC, avoids even using multiplication by resorting to clever bitshifts and a lookup table. Our go-to in these type of situations, Chebyshev polynomial approximation, didn’t even make the cut. (Although we suspect it would be a contender in the gamma=1.8 or gamma=2.2 cases, especially if combined with range-reduction in a first stage like [nats.fr] does.)

So what’s the best/fastest approximation for sqrt(x) for 16-bit integers on an FPGA? [nats.fr] is using a Spartan 6, so you can use a multiplier, but division is probably best avoided. What about arbitrary, possibly fractional, roots?

33C3 Starts Tomorrow: We Won’t Be Sleeping For Four Days

Possibly the greatest hacker show on Earth, the 33rd annual Chaos Communication Congress (33C3) begins Tuesday morning in Hamburg, Germany. And Hackaday will be there! Contributing Editor [Elliot Williams] is taking the night train up and will be trying to take it all in for you. The schedule looks tremendous.

If you can’t make it, don’t fret. There will be live streaming, and the talks are usually available in preliminary edit for viewing or download just a few minutes after they finish. It’s even cooler to watch the talks with friends, though. Every hackerspace with a video projector could be playing along, live or after the fact. Pick some cool talks and have a “movie night”.

elliot_williams_head_2_square_fuzzIf you’re going to be in Hamburg, and you want to show us something cool, tell us that something is NOTAHACK!1!! in person, or even just say “Hi”, we’ll be wandering around from talk to talk and session to session just like you, only with a backpack full of Hackaday stickers.

If there’s anything you think we should see, post up in the comments. If there’s enough call for it, we’ll have a Hackaday meetup once we can figure out a good time and location. Bring us a cool hack, and we’ll document it on the spot! Our DECT phone number is 2475.

Gecho Pocket Synth Looper

[Mario] wrote us with his synthesizer project that’s currently up on Kickstarter. It looks like a good amount of fun to play with, as you can see in the video on the Kickstarter page. But it’s also built to be easily hackable.

On the hardware front, it’s a tiny four-layer board that’s crammed with parts. At the core is an STM32F4 microcontroller and a DAC. Indeed, the build was inspired by other folks’ work on the STM32F4 Discovery dev kit that has been used to make some pretty interesting synthesizer devices. [Mario]’s version adds two stereo headphone outputs, two microphone inputs, two IR reflective distance sensors used as control inputs, some buttons, and a ton of LEDs. And then it makes good use of all of them.

The firmware isn’t open source yet (poke! poke!) but it looks like it’s going to be. On his blog, [Mario] works through an example of adding a drum machine into the existing firmware, so it looks like it’ll be hackable.

Squeezing a lot of DSP functionality out of a single microcontroller is a feat. On a similar chip from a different manufacturer, [Paul Stoffregen]’s Teensy Audio Library could also be made to do a lot of the same things. But the real beauty of the Gecho project is that it has some interesting hardware features already built in and ready to go. It wouldn’t be a bad launching pad for your own musical or audio explorations.

PURE Modules Aim To Make Prototyping Easier

[Sashi]’s PURE modules system wants your next wireless microcontroller and sensor module project to be put together using card-edge connectors. But it’s a lot deeper than that — PURE is an entire wireless gadget development ecosystem. Striking a balance between completeness and modularity is very difficult; a wire can carry any imaginable electronic signal, but just handing someone a pile of wires presents them a steep learning curve. PURE is at the other end of the spectrum: everything is specified.

So far, two microcontroller options are available in the system, the nRF52 series and TI’s CC2650. Both of these run the Contiki OS, so it doesn’t matter which of these you choose. Wired data is all transmitted over I2C and connects up via the previously-mentioned card-edge connectors. On the wireless side, data transport is handled through an MQTT broker, using the MQTT-sn variant which is better suited to small radio devices. At the protocol layer everything uses Protocol Buffers, Google’s newest idea for adding some structure to the data.

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3D Printing With Yarn And Silicone

This one is apparently a few years old, but the idea looks so good that we’re left wondering whatever happened to it.

[Seyi Sosanya] made what amounts to a 3D printer, but one that prints in a unique way: wrapping yarn around pillars and then post-dipping them in a silicone glue. The result is a tough, flexible 3D mesh that’s lightweight and looks fairly resilient. We’re not at all sure what it’s good for, but watching the video about the project (embedded below) makes us want to try our hand at this sort of thing.

So what happened? Where did this project go? Is anyone else working on a glue-plus-fabric style printer? Is anyone doing this with carbon fiber and epoxy? We can also imagine that with the right adhesive this could be used less like a loom and more like a traditional FDM machine, although weaving the layers together may provide additional strength in what would be the Z direction, and for that you’d need the supports.

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