A Petite Pico Projector For Portable Pi

A few years ago, new, innovative pico projectors, influenced by one of the TI development kits, started appearing in Kickstarter projects and other various DIY endeavours. Those projects fizzled out, most likely due to the cost of the projectors, but we got a few laughs out of it: that wearable smartphone that projected a screen onto your wrist used the same technology.

But there’s a need for a small projector, a pico projector, or in this case a femto projector. It’s the Nebra Anybeam, and it’s a small projector that uses lasers, and it comes in the form of a Raspberry Pi hat. We would like to congratulate the team for shipping the ideal use case of their product first.

The key features of this pico projector address the shortcomings of existing projectors that can fit in your pocket. This uses a laser, and there’s no bulb, and the power consumption can be as low as 3 Watts. Power is provided over a micro USB cable. The resolution of this projector is 720p, which is sufficient for a quick setup for watching a movie, but the brightness is listed as equivalent to 150 ANSI lumens, about the same as small projectors from a few years ago.

But of course the big selling point isn’t the brightness or resolution, it’s all about the smallness of the projector itself. There is a developer’s kit, a Pi Hat, a fit-in-your-pocket version with an enclosure, and a ‘monster ball’ version of the Anybeam.

Do You Know Where Your Drone is Headed? HJWYDK Article Explores Limits of MEMS Sensors

Knowing in what absolute direction your robot is pointed can be crucial, and expensive systems like those used by NASA on Mars are capable of calculating this six-dimensional heading vector to within around one degree RMS, but they are fairly expensive. If you want similar accuracy on a hacker budget, this paper shows you how to do it using cheap MEMS sensors, an off-the-shelf motion co-processor IC, and the right calibration method.

The latest article to be published in our own peer-reviewed Hackaday Journal is Limits of Absolute Heading Accuracy Using Inexpensive MEMS Sensors  (PDF). In this paper, Gregory Tomasch and Kris Winer take a close look at the heading accuracy that can be obtained using several algorithms coupled with two different MEMS sensor sets. Their work shows that when properly used, inexpensive sensors can produce results on par with much more costly systems. This is a great paper that illustrates the practical contributions our community can make to technology, and we’re proud to publish it in the Journal.

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Casio Watch Gets a MEMS Oscillator Upgrade

We’ve got to admit to being a bit of a Casio G-Shock watch geek. The big, chunky watches were every day carry items that survived everything we dished out, right up until the smartphone made wearing one seem redundant. But others continue to use and abuse G-Shocks, and some brave souls even hack them.

Replacing the standard quartz crystal with a temperature-compensated MEMS oscillator is one hack that [Alex] tried, and it appears to have worked out well. His project write-up doesn’t specify which MEMS oscillator was used, but we suspect it’s the SiT1552 TCXO. With its extremely small size, stability over a wide range of temperatures, and ultra-low power requirements, the chip is a natural choice to upgrade the stock 32.768-kHz quartz crystal of the watch. Trouble is, the tiny 1.5 mm x 0.8 mm chip-scale package (CSP) device presented some handling problems. After overcooking a few chips in the reflow oven, [Alex] was able to get one mounted to a tiny breakout board, which went into the space formerly occupied by the watch’s quartz crystal. He stole power for the TCXO from a decoupling capacitor, sealed the watch back up, and it’s back in service with better stability and longer battery life to boot. The video below shows the TCXO undergoing tests alongside the original quartz crystal and a comparatively huge DS3231 RTC module, just for fun.

[Alex]’s MEMS transplant seems a long way to go and a lot of fussy work for marginal gains, but who are we to judge? And it does make the watch susceptible to punking with a little helium, which might make things interesting.

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Piezoelectric Gyro Shows How They Rolled Back in the Day

There’s no doubting the wonders that micro-electromechanical systems (MEMS) technology have brought to the world. With MEMS chips, your phone can detect the slightest movement, turning it into a sensitive sensor platform that can almost anticipate what you’re going to do next. Actually, it’s kind of creepy when you think about it.

But before nano-scale MEMS inertial sensing came along, lots of products needed to know their ups from their downs, and many turned to products such as this vibrating piezoelectric gyroscope that [Kerry Wong] found in an old camcorder. The video below shows a teardown of the sensor, huge by MEMS standards but still a marvel of micro-engineering. The device is classified as a Coriolis vibratory gyroscope (CVG) which, as the name implies, uses the Coriolis effect to sense rotation. In this device, [Kerry] found that a long, narrow piezoelectric element spans the long axis of the sensor, suspended from what appears to be four flexible arms. [Kerry] probed the innards of the sensor while powered up and discovered a 22 kHz signal on the piezo element; this vibrates the bar in one plane so that when it rotates, it exerts a force on the support arms that can be detected. Indeed, [Kerry] hooked the output of the sensor to a wonderfully old-school VOM whose needle wiggled with the slightest movement of the sensor.

Sadly, MEMS made this kind of sensor obsolete, but we appreciate the look under the hood. And really, MEMS chips are using the same principle to detect motion, just on a much smaller scale. Want the MEMS basics? [Al] has you covered.

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[Ben Krasnow] Gasses MEMS Chips, for Science

Why in the world does helium kill iPhones and other members of the Apple ecosystem? Enquiring minds want to know, and [Ben Krasnow] has obliged with an investigation of the culprit: the MEMS oscillator. (YouTube, embedded below.)

When we first heard about this, courtesy in part via a Hackaday post on MRI-killed iPhones, we couldn’t imagine how poisoning a micro-electromechanical system (MEMS) part could kill a phone. We’d always associated MEMS with accelerometers and gyros, important sensors in the smartphone suite, but hardly essential. It turns out there’s another MEMS component in many Apple products: an SiT 1532 oscillator, a tiny replacement for quartz crystal oscillators.

[Ben] got a few from DigiKey and put them through some tests in a DIY gas chamber. He found that a partial pressure of helium as low as 2 kPa, or just 2% of atmospheric pressure, can kill the oscillator. To understand why, and because [Ben] has a scanning electron microscope, he lapped down some spare MEMS oscillators to expose their intricate innards. His SEM images are stunning but perplexing, raising questions about how such things could be made which he also addresses.

The bottom line: helium poisons MEMS oscillators in low enough concentrations that the original MRI story is plausible. As a bonus, we now understand MEMS devices a bit better, and have one more reason never to own an iPhone.

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How’s a Gyro Work?

It wasn’t long ago that a gyro — or gyroscope — was an exotic piece of electronics gear. Most of us only saw them as children’s toys that would balance on your finger. That’s changed, though, thanks to microelectronics. Now your game controller, your phone, and your drone all probably use little ICs that are actually three-axis gyroscopes. Ever wonder how they work and what they do? [RCModelReviews] has a video that covers three kinds of gyros: old mechanical gyros, modern MEMS gyros, and even an exotic laser-based gyro. (YouTube, embedded below.)

Gyroscopes allow you to detect orientation by detecting linear forces on a rotating element. They are used in everything from spacecraft to submarines. The device has many origins dating back to antiquity. But the modern gyro showed up around 1800 or so. The children’s toy appeared in 1917 and is still made today.

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Helium can Stop Your iPhone — Maybe Other MEMS, Too

Sometimes hacking isn’t as much about building something, it’s about getting to the root of a particularly difficult problem. [Erik Wooldrige] was facing a problem like that. He’s a system specialist at a hospital near Chicago. Suddenly a bunch of iPhones and Apple watches were failing or glitching. The only thing anyone could think of was the recent install of an MRI machine.

Sure, an MRI machine can put out some serious electromagnetic pulses, but why would that only affect Apple products? Everything else in the hospital, including Android phones, seemed to be OK. But about 40 Apple devices were either dead or misbehaving.

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