Who Ate All The Pi?

Wednesday was the last day of February, and leap year questions aside that date marks the anniversary of the Raspberry Pi launch. The oldest commercially available Pi is now 6 years old, and to mark the occasion the Raspberry Pi people have put up a retrospective of all their different models.

There is a primordial prototype from [Eben Upton]’s bench that involves an Atmel processor, but the first board dangled in front of the public was a Broadcom one, the BCM2763 ‘micro DB’. This was a form factor like one of those Android TV sticks, and while it was not a Raspberry Pi internal design or indeed sporting the SoC to be used by the Pi itself, it was sufficient to capture the imagination of what would become the Raspberry Pi community.

If you got out of bed early (British time) on the 29th of February 2012 and tried to order one of the first commercially available boards, you were most likely to be out of luck. The relatively small first batch from China was oversubscribed massively, both the RS and Farnell websites went down completely for most of the day. We received our model at some point in May. It’s an over-used phrase, “And the rest is history”, but it seems entirely appropriate here. The Pi has passed through several iterations and increased in both computing power and memory, it has spawned a whole industry of peripherals, a huge community, and a host of competitors. We have quite a few of the boards in the blog post, but some of the more exotic ones have evaded us.

It’s not the best or most powerful board out there, many of its competitors can beat it on performance, but it remains the one to beat in small and cheap Linux-capable single board computers. Why is this the case? It has probably the best-supported Linux distro of all of them, and that community has already answered many of the queries you might find with your board.

So there’s the story, a successful product line, community, and foundation. The Pi blog piece is very much their PR, but it doesn’t need to gild the lily. However, that will not stop competitors from taking aim at its crown, and the field remains open for one of them to topple it. Which of course makes for fascinating stories for us here at Hackaday, so we’d encourage anybody with an electronics factory in China, a bright team, and some good ideas to give it a try. Meanwhile, we’ll be looking towards Cambridge for whatever new products will sport the fruity logo.

Another Introduction to FPGAs

FPGAs can have a steep learning curve, so getting started tutorials are a popular topic. Intel recently published a video titled “Basics of Programmable Logic: FPGA Architecture” and you can see it below. Of course, Intel bought Altera, so the material has a bit of Altera/Intel flavor to it, but the course is generic enough that the concepts will apply to just about any FPGA.

Of course, if you do want to use Quartus, there are quite a few follow-on courses, including the wonderfully named “Become a [sic] FPGA Designer in 4 Hours.” We’d really like to see a sequel titled “Become a Proficient FPGA Designer in 9 Months” but Google didn’t turn that one up.

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Finding Noise with an Antenna

[K5ACL], aka [SignalSearch], recently brought his active receive loop antenna in off the roof to give it a checkup and perform any necessary maintenance. While it was in the shack, he took the opportunity to discuss how well it would perform indoors. The verdict? Not ideal. He’d mount it 50 feet away from the house if the HOA would let him.

Houses, and subsequently most ham shacks, are filled with noise sources that interfere badly with HF. So after spending a minute or so listening on an SDR, [K5ACL] demonstrates another use for this type of tightly-tuned antenna—as a noise detector.

The main culprit in [K5ACL]’s house is the ceiling light that’s right there in the shack. You can see the noise striping the waterfall as he turns it on and off. But the noise from the light is small potatoes compared to some other common household items, like those power line adapters that turn house wiring into networking cable. Those produce so much noise that even an active loop is really no match. Stay tuned after the break to watch [K5ACL] work the bands through the noise.

Loop antennas are great if you’re stuck in an apartment building or a congested city. They’re easy enough to make, whether you want a portable loop or a permanent installation.

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Pinging the Depths of a Rain Barrel

Rain barrels are a great way to go green, as long as your neighborhood doesn’t frown upon them. [NikonUser]’s barrel sits up high enough that he has to climb up on an old BBQ and half-dangle from the pipe to check the water level, all the while at the risk of encountering Australian spiders.

Arachnophobia, it turns out, is a great motivator. At first, [NikonUser] dreamed up a solar-powered IoT doodad that would check the level and report the result on a web page. He battled the Feature Creep and decided to build a handheld device that pings the water level with an ultrasonic sensor and displays it on a 7-segment.

Everything is contained in a water-resistant box and driven by an Arduino Pro. The box is mounted on a piece of scrap lumber that lays across the top of the barrel. This allows the HC-SR04’s eyes to peer over the edge and send pings toward the bottom. It also helps to keep the readings consistent and the electronics from taking a swim.

Operation is simple: [NikonUser] reaches up, sets the plank across the barrel, and pushes the momentary. This activates the Arduino, which prompts the HC-SR04 to take several readings. The code averages these readings, does a little math, and displays the percentage of water remaining in the barrel.

Interested in harvesting rain water, but not sure what to do with it? You can use it for laundry, pour it in the toilet tank instead of flushing, or make an automated watering system for your garden.

Laser Rotary Adapter Gets You Rolling

Laser cutters are becoming more garage-accessible with overseas imports, but plenty of us still need to drop in on the college campus or makerspace to get our cuts. Having a laser onsite is a nice touch, but having a rotary axis is almost unheard of. These nifty add-ons enable your laser to cut and engrave radially symmetric parts. Their pricetags usually fall in the hundred-to-thousand dollar price range, so while that might stop us there’s nothing holding us back from building our own!

That’s exactly what both [Cesar] and [Russ] did with two homebrew designs built from scraps, and the results look comparable to the professional default. The design itself is simple, yet dead clever. The carriage straps directly onto the x-axis such that its motion is rigidly connected to it. The wheels on the bottom play a dual role. First, they let the carriage slide smoothly with the y-axis motion. They also support the object-to-be-engraved and convert the wheel rotation from the y-axis movement into rotation of the object. There’s one drawback here in that the diameter of the object-to-be-engraved affects the angle of rotation, but we’ve never been ashamed to do a little work with θ = s/r.

[Cesar] gets the credit for putting this hack out for the world to see, but [Russ] also get’s a big thanks for putting out a downloadable file of his carriage. It’s a testament to how sharing a thought can inspire us to iterate on better designs that they world can enjoy.

Rolling fourth-axes aren’t anything new on these pages, but they’re certainly rare! If your hungry for more rolling axis goodness, have a look at [Perry’s] router modifications.

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Mechanisms: The Reed Switch

Just about everywhere you go, there’s a reed switch nearby that’s quietly going about its work. Reed switches are so ubiquitous that you’re probably never more than a few feet away from one at any given time, especially at home or in the car. You might have them on your doors and windows as part of a burglar alarm system. They keep your washing machine from running when the lid is open, and they put your laptop to sleep when you close the lid. They know if the car has enough brake fluid and whether or not your seat belt is fastened.

Reed switches are interesting devices with a ton of domestic and industrial applications. We call them switches, but they’re also sensors. In fact, they only do the work of a switch while they can sense a magnetic field. They are capable of switching AC or DC at low and high voltages, but they don’t need electricity to work. Since they’re sealed in glass, they are impervious to dirt, dust, corrosion, temperature swings, and explosive environments. They’re cheap, they’re durable, and in low-current applications they can last for about a billion actuations.

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Images As Excel FIles Are Gloriously Nasty

Almost every person of a technical persuasion who has worked in an office will have some tale of wildly inappropriate use of office technology for a task that could have been accomplished far more simply with an appropriate tool. There are jokes about people photocopying a blank sheet of paper when they need a few sheets themselves, but some of the real stories are very bit as surreal.

[Bjonnh]’s patience for such things was exceeded when he received a screenshot embedded in a Microsoft Word file. His response is both pointless and elegant, a Python script that takes a JPEG image and encodes it into an Excel file. It’s simply an array of cells whose background colours represent the pixels, and he warns us that the output files may take a while to load. We just had to subject it to a test, but are sorry to report that LibreOffice doesn’t seem to want to play ball.

So yes, this is a small departure from our usual fare of hardware, and it serves no use other than to be a fantastically awful misuse of office technology. If you’ve ever been emailed a PowerPoint invitation to the office party though, then maybe you’ll have cracked a smile.

If pushing your corporate spreadsheet to the limit is your thing, perhaps you’d also like to see it running a 3D engine.