Turning The Pi Zero Into A USB Gadget

December 27, 2015 by Brian Benchoff 60 Comments

The Raspberry Pi Zero is limited, or so everyone says, and everyone is trying to cram a USB hub and WiFi adapter on this tiny, tiny board. One thing a lot of people haven’t realized is that the Raspberry Pi Zero comes with a USB OTG port, meaning it can function as a USB device rather than a USB host. This means the Raspi can become a serial device with just a USB cable, an Ethernet device, MIDI device, camera, or just about anything else you can plug into a USB port. Adafruit has your back with a tutorial for using the USB OTG port as a serial and Ethernet interface, and the possible applications are extremely interesting.

The only requirement for using the USB OTG port for device applications is an update to the kernel. This is easily installed by dumping a few files on an SD card and a employing bit of command line wizardry. The simplest example is setting up the Pi Zero as a USB serial device, allowing anyone to log into a serial console on the Pi with just a USB cable.

A slightly more interesting application is setting up the Pi as an Ethernet gadget. This effectively tunnels all the networking on the Pi Zero through a USB cable and a separate computer. The instructions are extremely OS-specific, but the end result is the same: you can apt-get on a Pi Zero to your heart’s desire with a new kernel loaded onto the SD card and a USB cable.

This experimentation is just scratching the surface of what is possible with the OTG port on the Pi Zero. MIDI devices are easy, and with a ton of GPIOs, the Pi Zero itself could become a very interesting musical instrument. Want the Pi Zero to be a storage device? That’s easy too. The USB Gadget will end up being one of the most exciting uses for the Pi Zero, and we can’t wait to see what everyone will come up with next.

A Better Expanding Table

December 27, 2015 by Brian Benchoff 15 Comments

About a year ago, [Scott] completed what is probably one of the finest builds ever shown on a YouTube channel. It was an expanding wooden table, a build inspired by a fantastically expensive expanding table that was itself inspired by a creation by a mad woodworker in the early 1800s. Although [Scott]’s table is a very well-engineered build, there were a few things he wasn’t happy with. Over the past few months he’s been refining the design and has come up with the final iteration – and plans – for a wooden mechanical expanding table.

Late last year, [Scott] had about 450 hours of design and build time in his table, and by the time he got to the proof of concept stage, he simply ran out of steam. Another year brings renewed enthusiasm, and over the past month or so he’s been working on much-needed improvements to his expanding table that included a skirt for the side of the table, and improvements to the mechanics.

The expanding table is rather thick with three layers of tabletop stacked on top of each other, and those exposed mechanical linkages should be hidden. This means a skirt, and that requires a huge wooden ring. [Scott] built a ring 5 1/2″ deep, about an inch and a half thick, and has the same diameter of the table itself. This means cutting up a lot of plywood, and stacking, gluing, sanding, and routing the entire thing into a perfectly round shape.

The other upgrades were really about the fit and finish of the internal mechanics of the table. Screws were changed out, additional brackets were crafted, and the mounts for the internal ‘star’ was upgraded.

After all that work, is the table done? No, not quite; the skirt could use a veneer, proper legs need to be built, and the entire thing could use a finish. Still, this is the most complete homebuilt expanding table ever conceived, and [Scott] has the plans for his table available for anyone who would want to replicate his work.

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Nikon Resurrection: Repairing A Broken Lens

December 25, 2015 by Adam Fabio 14 Comments

Modern DSLR cameras are amazing devices. Mechanics, electronics, and optics, all rolled up in a single package. All that technology is great, but it can make for a frustrating experience when attempting any sort of repair. Lenses can be especially difficult to work on. One misalignment of a lens group or element can lead to a fuzzy image.

[Kratz] knew all this, but it didn’t stop him from looking for a cheap lens deal over on eBay. He found a broken Nikon DSLR 55-200mm 1:4-5.6 AF-S VR camera lens for $30. This particular lens is relatively cheap – you can pick up a new one for around $150 online. Spending $30 to save $120 is a bit of a gamble, but [Kratz] went for it.

The lens he bought mostly worked – the auto-focus and vibration reduction system seemed to be fine. The aperture blades however, were stuck closed. Aperture blades form the iris of a lens. With the blades closed down, the lens was severely limited to brightly lit situations. All was not lost though, as the aperture is a relatively simple mechanical system, which hopefully would be easy to repair.

Keeping screws and various parts in order is key when taking apart a lens. [Kratz] used a tip he learned right here on Hackaday: He drew a diagram of the screw positions on a thick piece of paper. He then stuck each screw right into the paper in its proper position.

Carefully removing each part, [Kratz] found a pin had slipped out of the rod that connects the lens’ internal parts with the external aperture control arm. Fixing the pin was simple. Getting the lens back together was quite a bit harder. Several parts have to be aligned blindly. [Kratz] persevered and eventually everything slipped into alignment. The finished lens works fine, albeit for a slightly noisy auto-focus.

It’s worth noting that there are service and repair manuals for many cameras and lenses out there in the dark corners of the internet, including [Kratz]’s 55-200 lens. Reading the repair procedures Nikon techs use shows just how many tools, fixtures, and custom bits of software go into making one of these lenses work.

The Ultimate Puzzle Desk — MYST Eat Your Heart Out

December 25, 2015 by James Hobson 11 Comments

This project is absolutely mind boggling. Created by [Kagen Sound], this desk would fit right at home inside the MYST games. It has a pipe organ inside, and you can open a secret compartment by playing a specific tune.

Besides being an absolute marvel of woodworking, the hidden mechanics inside this desk make our heads hurt. The pipe organ aspect works by pushing in little drawers — this forces air into organ pipes at the front of the desk. But some of the air is redirected into a pneumatic memory board — which can actually keep track of the notes you play. When the correct tune is played, it triggers a pendulum which releases a secret compartment. All you need is a trap door over an abyss and you’ve recreated The Goonies.

Sure, it’d be easy to do that with an Arduino or something… but the pneumatic memory board is made of wood. Entirely made of solid wood. [Kagen] says it took countless hours to design, at least five different versions before he found one that worked.

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You Can Learn A Lot From A Dummy (Load)

December 24, 2015 by Al Williams 53 Comments

If you work on RF circuits–even if you aren’t a ham radio operator–you ought to have a dummy load. A dummy load is a non-radiative “antenna” with known impedance that you can use to test your RF circuit without radiating. For radio work, you usually just need a 50-ohm resistor that is non-inductive (at least at the frequencies you are interested in) and that can dissipate the amount of power you’ll expect it to handle (at least for a short time). [VO1PWF] wanted a dummy load and built his own.
The Cantenna (not the Pringle’s kind; see right) was a famous dummy load design when Heathkit was in business. It was a single carbon rod immersed in a paint can full transformer oil (which we now know was full of dangerous PCBs; and we don’t mean printed circuit boards). [VO1PWF’s] design is a little more practical, using some resistors in parallel (20 1K resistors), a plastic pipe housing, and mineral oil to keep it all cool.

The reason for the parallel resistors is to maximize the power handling capability. The resistors are 3W units, so the dummy load–in theory–can handle 60 watts. Often, high power resistors are wire wound and thus have a good bit of parasitic inductance that makes the dummy load reactive (not a good thing since that makes the load impedance vary by frequency). They do make non-inductive wire wound resistors, but these aren’t truly non-inductive. The wire winds in two different directions, so the inductance tends to cancel out. We wouldn’t trust them to be a pure resistance in a high-power dummy load design.

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Firing Up A Raspberry Pi Zero

December 23, 2015 by Rud Merriam 38 Comments

I ordered a Raspberry Pi Zero from Adafruit in their Startup Pack right after they were released. There are a few Greater Than Zero Pis (GTZPi) already on my workbench so my purchase was driven by curiosity, not necessity. With no rush on delivery it eventually got here, and I finally got around to looking at it. My experience with the Pi family began with the Pi B+ and, shortly after that, the Pi 2. The speed difference between them was noticeable so I decided to dive in and further test the performance of the Zero.

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The ESP32 Beta Units Arrive

December 23, 2015 by Brian Benchoff 40 Comments

A little more than a year ago, the ESP8266 WiFi module showed up uneventfully in Seeed Studio’s store. Since then, the documentation has been translated to English, a proper development environment for this chip was created, and everybody is using this cheap but powerful chip for the latest Internet of Things things.

The company behind the ESP8266, Espressif, is not one to rest on their laurels, and for several months they’ve been working on the next generation of powerful WiFi-enabled tiny, cheap systems. They have their silicon, and already 200 lucky people have their hands on the very first test units of the ESP32, the next generation of Espressif’s WiFi chips. The teardowns have begun, and [LadyAda] streamed her initial experiments with the chip to the Intertubes (available below). [Martin] is also one of the guys who received these early beta chips, and he was kind enough to post his thoughts on Espressif’s newest chip.

A little bit of information on the ESP32 has dribbled out, and [LadyAda] and [Martin]’s demo unit confirm all we’ve suspected. There are two Tensilica L108 processors running at up to 160MHz, a lot of peripherals including ADCs, DACs, I2C, SPI, I2S, and PWM, more RAM, AES and SSL for security, and Bluetooth Low Energy. WiFi has also been upgraded, and the ESP32 will support speeds up to 150 Mbps.

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