The Physics Lesson I Keep Re-Learning

December 2, 2023 by Elliot Williams 69 Comments

One of the most broadly applicable ideas I’ve ever encountered is the concept of impedance matching. If you’re into radio frequency electronics, you’re probably thinking that I mean getting all your circuit elements working to a common characteristic resistance for maximum power transfer. (If you’re not, you’re probably wondering what that jumble of words even means. Fear not!)

But I mean impedance matching in the larger sense. Think about driving a stick-shift automobile. In low gear, the engine has a lot of torque on the wheels, but it can’t spin them all that fast. In high, the wheels turn fastest, but there’s not enough torque to get you started from a standstill. Sometimes you need more force and less motion, other times more motion and less force. The gearbox lets you match the motor’s power to the resistance – the impedance – it’s trying to overcome.

Or think about a cello. The strings are tight, and vibrate with quite a bit of force, but they don’t move all that much. Air, which is destined to carry the sound to your ear, doesn’t take much force to move, and the cello would play louder if it moved more of it. So the bridge conveys the small, but strong, vibrations of the strings and pushes against the top of the resonant box that makes up the body of the instrument. This in turn pushes a lot of air, but not very hard. This is also why speakers have cones, and also why your ear has that crazy stirrup mechanism. Indeed, counting the number of impedance matches between Yo Yo Ma and your brain, I come up with four or five, including electrical matches in the pre-amp.

I mention this because I recently ran into a mismatch. Fans blow air either hard or in large volume. If you pick a fan that’s designed for volume, and put it in a pressure application, it’s like trying to start driving in fifth gear. It stalled, and almost no air got pushed up through the beans in my new “improved” coffee roaster, meaning I had to rebuild it with the old fan, and quick before the next cup was due.

I ran into this mismatch even though I knew there was a possible impedance issue there. I simply don’t have a good intuitive feel how much pressure I needed to push the beans around – the impedance in question – and I bought the wrong fan. But still, knowing that there is a trade-off is a good start. I hope this helps you avoid walking in my footsteps!

Thanks For Hacking

November 25, 2023 by Elliot Williams 11 Comments

Hope you’re all having a great Thanksgiving weekend, and are getting your fill of family, food, and maybe even a little bit of fun. Aside from the cranberries, Thanksgiving is probably one of my favorite holidays because of the spirit behind it – thinking about what’s gone well, how you lucked out, and who has done you right over the year.

One of the most poignant expressions of thanks I’ve heard in a while came from Hackaday superfriend [Sprite_tm] in his Supercon talk this year, which he closed by thanking “you all” for pushing him on to keep making crazy projects. “I would never finish these projects without people who would be entertained by seeing all this. This is is effectively art – something that doesn’t make sense. The only way it makes sense is because I want it to exist, and because I know that you all love hearing and reading about stuff like this existing. So thank you very much for that.”

That same sentiment goes for all of us here at Hackaday: Thank you all very much for reading! Without this global community of crazy hackers to write for, we wouldn’t be able to keep doing what we do – it just wouldn’t make sense. And without your hacks, of course, we’d have nothing to write about.

Thanks for sharing, thanks for following along, thanks for inspiring us and for being inspired. Thanks for hacking.

Does Getting Into Your Garage Really Need To Be Difficult?

November 9, 2023 by Dan Maloney 78 Comments

Probably the last thing anyone wants when coming home from a long day at work or a trip is to be hassled at the last possible moment — gaining entrance to your house. But for some home automation enthusiasts, that’s just what happened when they suddenly learned that their own garage doors had betrayed them.

The story basically boils down to this: Chamberlain, a US company that commands 60% of the garage door market, recently decided to prevent “unauthorized usage” of their MyQ ecosystem through third-party apps. Once Chamberlain rolled out the change, users of Home Assistant and other unauthorized apps found themselves unable to open or close their doors with the apps they were accustomed to.

Those of us with custom smart home setups can relate to how frustrating it is when something disturbs the systems you’ve spent a lot of time tweaking and optimizing. It’s especially upsetting for users who both Chamberlain hardware specifically because it was supported by Home Assistant, only to have the company decide to drop support. This feels like false advertising, but we strongly suspect that buried in the EULA users must have agreed to at some point is a clause that essentially says, “We can do anything we want and tough noogies to you.” And if you read through the article linked above, you’ll get an idea why Chamberlain did this — they probably didn’t like the idea that users were avoiding their ad-spangled MyQ app for third-party interfaces, depriving them of ad revenue and the opportunity for up-selling.

We feel the frustration of these users, but rather than curse the darkness, perhaps this will light a candle of righteous rage that leads to a clever workaround. The Home Assistant blog article mentions a dongle called ratgdo, which should allow any door with plain old dry contacts to work via MQTT or ESPHome. It’s extra work that users shouldn’t have to put in, but maybe getting one over on The Man would be worth the effort.

Thanks to [KC] for the tip; please keep us posted on your workaround.

The UK Online Safety Bill Becomes Law, What Does It Mean?

October 29, 2023 by Jenny List 65 Comments

We’ve previously reported from the UK about the Online Safety Bill, a piece of internet safety legislation that contains several concerning provisions relating to online privacy and encryption. UK laws enter the statutes by royal assent after being approved by Parliament, so with the signature of the King, it has now become the law of the land as the Online Safety Act 2023. Now that it’s beyond amendment, it’s time to take stock for a minute: what does it mean for internet users, both in the UK and beyond its shores? Continue reading “The UK Online Safety Bill Becomes Law, What Does It Mean?” →

Impostor Syndrome: It’s Not Your Fault!

October 28, 2023 by Elliot Williams 68 Comments

[Crispernaki] and I have something in common. We both saw this awesome project that made a scroll wheel out of a VHS head back in 2010, and wanted to make one. We both wanted to put our own spin on the gadget, (tee-hee), discovered that it was harder than either of us wanted to commit to, and gave up.

Flash forward about a million Internet years, and [crispernaki] finally made his and wrote it up. The only problem is that it was too easy. In 2010, making USB gadgets was a lot more involved than it is today. (Back then, we had to chisel device descriptors on stone tablets.) Nowadays, the firmware is just a matter of importing the right library, and the hardware is a magnetic rotation sensor breakout board, a magnet, and super glue. Cheap, and easy.

All of this led our hero to feeling insecure. After all, a hack that beat him a dozen years ago turned out to be dead easy today. Maybe it was too easy? Maybe he wasn’t a “real” hacker? These are the signs of impostor syndrome – that feeling that just because you aren’t the world’s best, or climbing the highest mountain, or hacking the hardest project, you’re not worthy.

Well, listen up. Impostors don’t finish projects, and impostors don’t write them up to share with all the rest of us. By actually doing the thing – hacking the hack – all chances of being a fake are ruled out. The proof is sitting there on your desk, in all its Altoids-tin glory.

And it’s not your fault that it was too easy this time around. You can’t do anything to turn back the hands of time, to make the project any harder these days, or to undo the decade of hacker technical progress on the software side, much less change the global economy to make a magnetic sensor unobtainable again. The world improved, you got your hack done, and that’s that. Congratulations! (Now where do I buy some of those on-axis magnets?)

NFTs And Tulipmania: A Little Bit Of History Repeating

October 20, 2023 by Al Williams 123 Comments

We were not surprised to read that a company that tracks NFTs declared that most NFTs are now worthless. But the NFT — non-fungible token — market was huge, so around 23 million people invested in NFTs that are now worth nothing. Worse still, the company notes that because of oddities in how NFTs are priced, the real number of worthless assets is probably even greater than they think.

It is easy to look back and think that it was obvious. After all, an NFT of the Mona Lisa isn’t really the Mona Lisa. Nor does owning it confer any real benefit other than “bragging rights” of owning an NFT of the Mona Lisa. But that’s like saying Luke should have known Darth Vader was his father — it’s only evident after the fact. History is replete with bad ideas at the time that paid out down the road. Of course, history is also full of bad ideas that were simply bad ideas. For every Apple or Google stock you didn’t buy at $4 a share, there are a hundred $4 stocks that you shouldn’t have bought.

The Virus

The NFT craze was sort of a viral event. We usually think of these as part of the Internet culture, but that’s not really true. There is actually very little new on the Internet. The Internet just lets things reach further and faster than before.

Don’t believe me? Kilroy was a viral meme in the 1940s. Fads such as hula hoops, phone booth stuffing, and flagpole sitting were the ice bucket challenges of their day. But, of course, these things weren’t economic. Just fun fads. But economic fads that turn out to be a bad idea are nothing new, either.

Continue reading “NFTs And Tulipmania: A Little Bit Of History Repeating” →

Close To The Metal

October 14, 2023 by Elliot Williams 81 Comments

Firmware is caught between hardware and software. What do I mean? Microcontroller designers compete on how many interesting and useful hardware peripherals they can add to the chips, and they are all different on purpose. Meanwhile, software designers want to abstract away from the intricacies and idiosyncrasies of the hardware peripherals, because code wants to be generic and portable. Software and hardware designers are Montagues and Capulets, and we’re caught in the crossfire.

I’m in the middle of a design that takes advantage of perhaps one of the most idiosyncratic microcontroller peripherals out there – the RP2040’s PIOs. Combining these with the chip’s direct memory access (DMA) controllers allows some fairly high-bandwidth processing, without bogging down the CPUs. But because I want this code to be usable and extensible by a wide audience, I’m also trying to write it in MicroPython. And configuring DMA controllers is just too idiosyncratic for MicroPython.

But there’s an escape hatch. In my case, it’s courtesy of the machine.mem32 function, which lets you read and write directly into the chip’s memory, including all of the memory-mapped configuration registers. Sure, it’s absurdly low-level, but it means that anything you read about in the chip’s datasheet, you can do right away, and from within the relative comfort of a Micropython program. Other languages have their PEEK and POKE equivalents as well, or allow inline assembler, or otherwise furnish you the tools to get closer to the metal without having to write all the rest of your code low level.

I’m honestly usually a straight-C or even Forth programmer, but this experience of using a higher-level language and simultaneously being able to dive down to the lowest levels of bit-twiddling at the same time has been a revelation. If you’re just using Micropython, open up your chip’s datasheet and see what it can offer you. Or if you’re programming at the configure-this-register level, check out the extra benefits you can get from a higher-level language. You can have your cake and eat it too!