Hackaday Prize Entry: A Very Small Password Keeper

One of the more popular security builds in recent memory is USB password vaults. These small thumb drive-sized devices hold all the passwords you have to deal with, and are locked behind a authentication code on the drive itself. For their Hackaday Prize entry, [Miguel] and [Noel] asked how inexpensively one of these devices could be made. The answer, coming in the form of their Memtype project, is very inexpensively.

The Memtype project is based on the cheapest and most simplistic USB implementation on the planet. It’s built around an ATtiny85 and V-USB‘s software only implementation of a USB keyboard, requiring only a few resistors and diode in addition to the ‘tiny85 itself.

The device can only be unlocked with a four-digit pin, input through the clever use of a small SMD joystick. After inputting the correct code, the Memtype grants the user access to all the stored passwords. As far as security goes, [Miguel] and [Noel] have implemented NOEKEON in assembly, however it should be noted that all security is weaker than a pipe wrench. For managing the passwords, [Miguel] and [Noel] built a small, simple GUI app to set the PIN and write credentials to the device.

[Miguel] and [Noel] already have a demo video up for the Memtype, you can check that out below.

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Smallest MIDI Synth, Again!

Not content with fitting a tiny square-wave MIDI synthesizer into a MIDI plug, [Mitxela] went on to cram a similar noisemaker into a USB plug itself.

Besides being physically small, the code is small too, as well as the budget. It uses V-USB for the USB library running on an ATtiny85, and a couple of passive parts. His firmware (apparently) takes in MIDI notes and spits out square waves.
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Simple Fuel Pressure Alarm Averts Diesel Disaster

If you could spend a couple of bucks on a simple project that might prevent a $2000 repair bill on your vehicle, you’d probably build it, right? That’s the idea behind this simple low-pressure alarm for a diesel fuel system, and it’s so simple it makes you wonder why the OEM didn’t do it.

We normally see [Bob Johnson] coming up with nifty projects (like this claw or this camera slider) that more often than not combine woodworking and electronics. But no tree carcasses were harmed in the making of this project. [Bob]’s goal is just to sound a warning and flash a light if the output of a pressure switch goes to ground. That indicates the lift pump in his Dodge Ram’s fuel tank has failed, which could lead to the sudden failure of the downstream injector pump for lack of lubrication by the fuel itself. His simple ATtiny85 circuit lives on a small perfboard in a 3D printed case and taps into a $30 fuel pressure switch. The microcontroller code enables a short delay to prevent nuisance alarms, and if the pressure drops below 5 PSI, [Bob] gets a chance to shut down the engine and disappoint his mechanic to the tune of $2000.

Maybe it’s planned obsolescence on the OEM’s part, or maybe it’s not. But kudos to [Bob] for a simple hack that averts a potentially expensive problem.

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Tiny ATtiny85 Game Console

[Ilya Titov] has made a game console. Not just any game console, but an extremely small ATtiny85-based console suitable for putting on a key ring and assembled into a very professional product with PCB and 3D printed case. This is a project that has been on the go since 2014, but the most recent update is a new version designed for tighter and more easy assembly.

All construction is through-hole rather than SMD, and aside from the ATtiny85 the console uses an OLED screen, piezo buzzer, tactile switches and a handful of passive components. Power comes from a single CR2032 coin cell which sits under the screen. Best of all the PCB design is available as a PDF and the 3D printed case can be found on Thingiverse.

There are two games for the console, as well as the Breakout clone whose code is in the 2014 piece linked above he’s written UFO Escape, an obstacle-avoiding side-scroller. You’ll have to burn both game and 8MHz internal clock bootloader to the ATtiny85 yourself. There are no cartridges with this console, though if the processor sits in a DIP socket the game can be changed over simply by swapping processors programmed with the appropriate game.

He’s produced a full assembly video with some UFO Escape gameplay thrown in, shown here below the break.

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EP Composes a New Chiptune Each Time

[Captain Credible] is a chiptune music artist. He wanted to release an EP, but a regular old em-pee-three was too lame for him, so he made a tiny board with a coin cell, an ATtiny85, and a 3.5mm socket on it.

Rather than just writing some code to generate the tones for a pre-composed song, his “Dead Cats” EP generates the music itself. Using the arduino-tiny library, which adds the tone() function to the ATtiny, he has the chip pick its own time signature, key, subdivisions, and tempo. The melody and drum beat is randomly generated into an array. In addition to that, there are some code “one-liners” which insert unique sounds. After that the code just loops through the music.

If you don’t like the song, simply unplug the audio cable and plug it back in. The 3.5mm jack he chose has a built-in micro-switch, so the board is only powered up if someone is listening. If you’d like to see the circuit diagram, purchase the EP, or take a look at the code, all of that is available on his site.

ATtiny Watch is Tiny

[陳亮] (Chen Liang) is in the middle of building the ultimate ring watch. This thing is way cooler than the cheap stretchy one I had in the early 1990s–it’s digital, see-through, and it probably won’t turn [陳]’s finger green.

watch-gutsThe current iteration is complete and builds upon his previous Arduino-driven watch building experiences. It runs on an ATtiny85 and displays the time, temperature, and battery status on an OLED. While this is a fairly a simple build on paper, it’s the Lilliputian implementation that makes it fantastic.

[陳] had to of course account for building along a continuous curve, which means that the modules of the watch must be on separate boards. They sit between the screw bosses of the horseshoe-shaped 3D-printed watch body, connected together with magnet wire. [陳] even rolled his own coin cell battery terminals by cutting and doubling over the thin metal bus from a length of bare DuPont connector.

If you’re into open source watches but prefer to wear them on your wrist, check out this PIC32 smart watch or the Microduino-based OSWatch.

A Power Switch for the Chromecast

Chromecasts are fantastic little products, they’re basically little HDMI sticks you can plug into any monitor or TV, and then stream content using your phone or computer as the controller. They are powered by a micro USB port in the back, and if you’re lucky, your TV has a port you can suck the juice off. But what if you want to turn it off while you use a different input on your TV so that your monitor will auto-sleep? You might have to build a power switch.

Now in all honesty, the Chromecast gets hot but the amount of power it draws when not in use is still pretty negligible compared to the draw of your TV. Every watt counts, and [Ilias] took this as an opportunity to refine his skills and combine a system using an Arduino, Bluetooth, and Android to create a robust power switch solution for the Chromecast.

The setup is rather simple. An HC-05 Bluetooth module is connected to an Attiny85, with some transistors to control a 5V power output. The Arduino takes care of a bluetooth connection and uses a serial input to control the transistor output. Finally, this is all controlled by a Tasker plugin on the Android phone, which sends serial messages via Bluetooth.

All the information you’ll need to make one yourself is available at [Ilias’] GitHub repository. For more information on the Chromecast, why not check out our review from almost three years ago — it’s getting old!