Why Won’t This Darn Thing Charge?

April 17, 2018 by Brian McEvoy 33 Comments

What is more fun than plugging in your phone and coming back to find your battery on empty? Stepping on a LEGO block with bare feet or arriving hungry at a restaurant after closing probably qualify. [Alex Sidorenko] won’t clean your floors or order you a pizza, but he can help you understand why cheap chargers won’t always power expensive devices. He also shows how to build an adapter to make them work despite themselves.

The cheapest smart device chargers take electricity from your home or car and convert it to five volts of direct current. That voltage sits on the power rails of a USB socket until you plug in a cable. If you’re fortunate, you might get a measly fuse.

Smart device manufacturers don’t make money when you buy an off-brand charger, and they can’t speak to the current protection of them, so they started to add features on their own chargers to protect their components and profit margins. In the case of dedicated chargers, a simple resistor across the data lines tells your phone it is acceptable power. Other devices are more finicky, but [Alex Sidorenko] shows how they work and provides Eagle files to build whatever flavor you want. Just be positive that your power supply is worthy of the reliability these boards promise to the device.

Now you know why connecting a homemade benchtop power supply to a USB cable seems good on paper but doesn’t always get the job done. Always be safe when you make your own power supplies.

Ask Hackaday: What’s In Your Digital Bugout Bag?

April 9, 2018 by Dan Maloney 119 Comments

Your eyes pop open in the middle of the night, darting around the darkened bedroom as you wonder why you woke up. Had you heard something? Or was that a dream? The matter is settled with loud pounding on the front door. Heart racing as you see blue and red lights playing through the window, you open the door to see a grim-faced police officer standing there. “There’s been a hazardous materials accident on the highway,” he intones. “We need to completely evacuate this neighborhood. Gather what you need and be ready to leave in 15 minutes.”

Most people will live their entire lives without a scenario like this playing out, but such things happen all the time. Whether the disaster du jour is man-made or natural, the potential to need to leave in a big hurry is very real, and it pays to equip yourself to survive such an ordeal. The primary tool for this is the so-called “bugout bag,” a small backpack for each family member that contains the essentials — clothing, food, medications — to survive for 72 hours away from home.

A bugout bag can turn a forced evacuation from a personal emergency into a minor inconvenience, as those at greatest risk well know — looking at you, Tornado Alley. But in our connected world, perhaps it pays to consider updating the bugout bag to include the essentials of our online lives, those cyber-needs that we’d be hard-pressed to live without for very long. What would a digital bugout bag look like?

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Threat Meter Gauges Risk Of Creeper-Assisted Suicide

February 18, 2018 by Dan Maloney 21 Comments

If you’ve played even just a few minutes of Minecraft, you know what a creeper is. For those not familiar with the wildly popular sandbox game, a creeper is a monster that creeps along silently until it’s close to a player, whereupon it self-destructs by exploding. Sometimes it kills the player outright, and other times the explosion blows them into lava or off a cliff, or off a cliff and then into lava. Creepers have no friends.

But now there’s a way to avoid creeper attacks, or at least get a little heads up that these green nasties are lurking about. With [John Allwine]’s creeper detector, Minecraft players can get a real-world indicator of the current in-game creeper threat. The hardware end is simple enough — it’s just a SparkFun RedBoard and a small strip of Neopixels in a laser-cut plywood case. The LEDs lie behind a piece of etched acrylic to diffuse their glow — extra points for the creeper pattern in the lens. The detector talks over USB to a Minecraft mod that [John] wrote to interface the game with the real world. The closer a creeper gets to the player, the brighter the light. — and when it flashes, watch out. See it in action in the video below, if you can stomach watching someone dig straight down. Never dig straight down.

If interfacing the Minecraft world and the real world sounds familiar, maybe it’s because we featured [John]’s SerialCraft mod a while back and admired the potential for using Minecraft as a gateway for getting kids into hardware hacking. We agree that this is a great project to work on with kids, but we may just order the parts to do it for our own Minecraft world. Creeper hate isn’t just for kids.

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Careful Testing Reveals USB Cable Duds

February 2, 2018 by Dan Maloney 29 Comments

What’s worse than powering up your latest build for the first time only to have absolutely nothing happen? OK, maybe it’s not as bad as releasing the Magic Smoke, but it’s still pretty bewildering to have none of your blinky lights blink like they’re supposed to.

What you do at that point is largely a matter of your troubleshooting style, and when [Scott M. Baker]’s Raspberry Pi jukebox build failed to chooch, he returned to first principles and checked the power cable. That turned out to be the culprit, but instead of giving up there, he did a thorough series of load tests on multiple USB cables to see which ones were suspect, with interesting results.

[Scott] originally used a cable with a USB-A on one end and a 3.5-mm barrel plug on the other with a switch in between, under the assumption that the plug on the Pi end would be more robust, as well as to have a power switch for the jukebox. Testing that cable using an adjustable DC load would prove that the cable was unfit for Pi duty, dropping the voltage to under 2 volts at a measly 500-mA load. Other cables proved much better under load, even those with USB mini jacks and even one with a 5.5-mm barrel. But the larger barrel-plug cable also proved to be a stinker when it was paired with an inline switch. In the video below, [Scott] walks through not only the testing process, but also gives a quick tour of his homebrew DC load.

The lesson is clear: not all USB cables are created equal, so caveat hacker. And if you’ve got a yen to check the cables in your junk bin like [Scott] did, this full-featured smart DC load might be just the thing.

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Tomu: A Microcontroller For Your USB Port

January 20, 2018 by Eric Evenchick 47 Comments

Looking for a ultra tiny development board? Tomu is an ARM Cortex M0+ device that fits inside your USB port. We’ve seen these in person, and they’re tiny.

There’s a few commercial devices in this form factor on the market. For example, the Yubikey Nano emulates a keyboard to provide codes for two-factor authentication. The Yubikey’s tiny hardware does this job well, but the closed-source device isn’t something you can modify.

Tomu is a new device for your USB port. It sports a Silicon Labs EFM32 microcontroller, two buttons, and two LEDs. This particular microcontroller is well suited to the task. It can talk USB without a crystal for timing, and has an internal regulator to generate the core voltage from a 5 V USB supply. Since it supports DFU firmware updates, it can be reprogrammed without any special tools.

Unfortunately, the EFM32 device lacks secure storage options, so the Tomu might not be the best device to keep your secrets on. That being said, it will be interesting to see what applications people come up with. The creators have suggested using the device for media buttons, sleeping and waking a computer, and as a U2F key.

The project is currently available on CrowdSupply, and all design files and source is available on their Github. If you like soldering tiny things, the twelve-part bill of materials should be fairly easy to assemble at home.

This USB Drive Will Self-Destruct After Ruining Your Computer

January 19, 2018 by Dan Maloney 35 Comments

Who would have thought that you could light up pyrotechnics on USB power? This USB keystroke injector that blows up after it’s used proves the concept.

Fully aware that this is one of those “just because you can doesn’t mean you should” projects, [MG] takes pains to point out that his danger dongle is just for dramatic effect, like a prop for a movie or the stage. In fact, he purposely withholds details on the pyrotechnics and concentrates on the keystroke injection aspect, potentially nasty enough by itself, as well as the dongle’s universal payload launching features. We’re a little bummed, because the confetti explosion (spoiler!) was pretty neat.

The device is just an ATtiny85 and a few passives stuffed into an old USB drive shell, along with a MOSFET to trigger the payload. If you eschew the explosives, the payload could be anything that will fit in the case. [MG] suggests that if you want to prank someone, an obnoxious siren might be a better way to teach your mark a lesson about plugging in strange USB drives.

While this isn’t the most dangerous thing you can do with a USB port, it could be right up there with that rash of USB killer dongles from a year or so ago. All of these devices are fun “what ifs”, but using them on anything but your own computers is not cool and possibly dangerous. Watching the smoke pour out of a USB socket definitely drives home the point that you shouldn’t plug in that thumbdrive that you found in the bathroom at work, though.

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Home Decorating With Tiny Arcade Cabinets

January 12, 2018 by Tom Nardi 19 Comments

Thanks to the general miniaturization of electronics, the wide availability of cheap color LCD screens, and the fact that licensing decades old arcade games is something of a free-for-all, we can now purchase miniature clones of classic arcade cabinets for about $20 USD. In theory you could play these things, but given they’re less than 4 inches in height they end up being more of a desk novelty than anything. Especially since it seems like most of the effort went into making the cabinet itself; a classic example of “form over function”.

Unfortunately, if you want to buy these little arcade cabinets to use as decoration for your office or game room, they aren’t particularly well suited to the task. The “demo” mode where the game plays itself doesn’t last for very long, and even if it did, the game would chew through batteries at an alarming rate. [Travis] decided to tackle both issues head on by powering his Tiny Arcades over USB and locking them into demo mode.

The stock power for the Tiny Arcade comes from three AAA batteries, or 4.5 V. This made it easy enough to run over 5 V USB, and a four port USB charger is used to provide power to multiple machines at once. Forcing the game to stay in demo mode wasn’t much harder: a 555 timer was used to “push” the demo button with a frequency of every 10 seconds or so to keep the game up and running. A simple timer circuit was put together in the classic “dead bug” style, and sealed up with liquid rubber so it would play nice with the insides of the Tiny Arcade.

Since his little machines wouldn’t need their stock power switches anymore, [Travis] rewired the speaker lead through it. So now the machine stays on and in demo mode as long as it’s plugged into USB power, and you can flip the switch on the back to turn off the sounds. Perfect for sitting up on a shelf or the corner of your desk.

Usability issues not withstanding, there’s a pretty big (no pun intended) following for micro sized arcade cabinets. We’ve seen projects ranging from modding a Game Boy Advance to even tinier scratch builds.

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