Raspberry Pi Gets Turned On

The Raspberry Pi and other similar Linux-based single board computers simplify many projects. However, one issue with Linux is that it doesn’t like being turned off abruptly. Things have gotten better, and you can certainly configure things to minimize the risk, but–in general–shutting a Linux system down while it is running will eventually lead to file system corruption.

If your project has an interface, you can always provide a shutdown option, but that doesn’t help if your application is headless. You can provide a shutdown button, but that leaves the problem of turning the device back on.

[Ivan] solved this problem with–what else–an Arduino (see the video below). Simplistically, the Arduino reads a button and uses a FET to turn off the power to the Pi. The reason for the Arduino, is that the tiny processor (which draws less than a Pi and doesn’t mind being shut down abruptly) can log into the Pi and properly shut it down. The real advantage, though, is that you could use other Arduino inputs to determine when to turn the Pi on and off.

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Hackaday Prize Entry: MyComm Handheld Satellite Messenger

We live in a connected world, but that world ends not far beyond the outermost cell phone tower. [John Grant] wants to be connected everywhere, even in regions where no mobile network is available, so he is building a solar powered, handheld satellite messenger: The MyComm – his entry for the Hackaday Prize.

The MyComm is a handheld touch-screen device, much like a smartphone, that connects to the Iridium satellite network to send and receive text messages. At the heart of his build, [John] uses a RockBLOCK Mk2 Iridium SatComm Module hooked up to a Teensy 3.1. The firmware is built upon a FreeRTOS port for proper task management. Project contributor [Jack] crafted an intuitive GUI that includes an on-screen keyboard to write, send and receive messages. A micro SD card stores all messages and contact list entries. Eventually, the system will be equipped with a solar cell, charging regulator and LiPo battery for worldwide, unconditional connectivity.

2016 will be an interesting year for the Iridium network since the first satellites for the improved (and backward-compatible) “Iridium NEXT” network are expected to launch soon. At times the 66 Iridium satellites currently covering the entire globe were considered a $5B heap of space junk due to deficiencies in reliability and security. Yet, it’s still there, with maker-friendly modems being available at $250 and pay-per-use rates of about 7 ct/kB (free downstream for SDR-Hackers). Enjoy the video of [Jack] explaining the MyComm user interface:

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Ghostbuster Proton Pack Made from Everything

[John Fin] put a lot of work into his Ghostbuster’s proton pack prop with full-featured user control and effects. What appealed to us well beyond the exquisite build is the extra effort taken to write down the whole process in a PDF for anyone wishing to imitate him.

Mr. Fusion is just a Krups Coffee Grinder. Also, Santa isn't real.
Mr. Fusion is just a Krups Coffee Grinder. Also, Santa isn’t real.

We all know that a lot of famous props are creatively rearranged household items. The famous Mr. Fusion from Back to The Future is actually a Krups coffee grinder with some logos adhered.

[John]’s prop is no different. The cyclotron is a five gallon bucket. A garlic powder container fills another function. As you look at it more and more items can be picked out. Is that a spark plug wire? The handles on that are suspiciously similar to a power tool case’s. It all comes together, and while it’s not screen accurate you’d have to be an extreme prop fanatic to tell.

Naturally, the core of [John]’s prop is an Arduino. It stores the sound files on a SD Card shield. It controls all the lights sounds and motors on the prop. This isn’t quite a point and shoot. You must toggle on the power, generator, and arming mechanisms before actually firing. If you do it out of order, the electronics will issue an alarm as warning, and each step in the process has its own unique audio and animated lighting.

Since the Proton Pack went so well, he also built a PKE meter and Ghost Trap to go along with his backpack. He’s ready to take on Vigo at anytime. You can see a video of his prop in action after the break.

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This Arduino Console Has 64 Bit Graphics

Numbers are wonderful things when applied to technical specifications. Take [Bobricius]’ handheld Arduino-based game console. With an 8×8 LED matrix for a display it’s not going to win any prizes, but while he’s pushing the boundaries of dubious specification claims he’s not strictly telling any lies with his tongue-in-cheek statement that the graphics are 64-bit.

Jokes aside, it’s a neatly done build using a DIP version of the Arduino MCU and all through-hole components on a custom PCB. Power comes from a CR2032 cell, and it includes three buttons and a small piezoelectric speaker. He’s implemented a whole slew of games, including clones of Pong, Breakout, and Tetris, and judging by the video below it’s surprisingly playable.

Now you might look at this console and wonder what the big deal is. After all, there are plenty of similar designs to be found, and it’s nothing new. Of course, it’s a neat project for any hacker or maker, but we can see that this would make a great starter project for the younger person in your life who wants to try their hands at building something electronic. All through-hole construction for easy soldering, and a neat game at the end of it all.

He’s posted a full write-up of the design process as well as the hackaday.io page linked above, so if you fancy building one yourself there’s nothing to stop you too squeezing 64 bits of graphical goodness from an Arduino.

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Taming Robot Arm Jump with Accelerometers

Last fall, I grabbed a robot arm from Robot Geeks when they were on sale at Thanksgiving. The arm uses servos to rotate the base and move the joints and gripper. These work well enough but I found one aspect of the arm frustrating. When you apply power, the software commands the servos to move to home position. The movement is sufficiently violent it can cause the entire arm to jump.

This jump occurs because there is no position feedback to the Arduino controller leaving it unable to know the positions of the arm’s servos and move them slowly to home. I pondered how to add this feedback using sensors, imposing the limitation that they couldn’t be large or require replacing existing parts. I decided to try adding accelerometers on each arm section.

Accelerometers, being affected by gravity when on a planet, provide an absolute reference because they always report the direction of down. With an accelerometer I can calculate the angle of an arm section with respect to the direction of gravitational acceleration.

Before discussing the accelerometers, take a look at the picture of the arm. An accelerometer would be added to each section of the arm between the controlling servos.

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Minecraft Trojan Horse Teaches Kids to Love Electronics and Code

Kids love Minecraft, and a clever educator can leverage that love to teach some very practical skills. The summer class offered by the Children’s Museum in Bozeman Montana would have blown my mind if such a thing existed when we were younger. (Rather than begging one of the dads in my Boy Scout Troop to pirate Visual Studio for me, which was delivered in the form of an alarmingly tall stack of CDs.) The kids in Bozeman get to learn hardware, software, their integration, and all while playing Minecraft.

Minecraft is an immersive universe that has proven to suck in creative minds. It’s the bait that pulls the kids into the summer class but Serialcraft delivers on making the learning just as addictive. This is accomplished by providing students with physical objects that are tied to the Minecraft world in meaningful ways we just haven’t seen before (at least not all at one time). On the surface this adds physical LEDs, toggle switches, potentiometers, and joysticks to the game. But the physical controls invite understanding of the mechanisms themselves, and they’re intertwined in exciting ways, through command blocks and other in-game components that feel intuitive to the students. From their understanding of the game’s mechanics they understand the physical objects and immediately want to experiment with them in the same way they would new blocks in the game.

The thing that makes this magic possible is a Minecraft mod written by [John Allwine], who gave us a demonstration of the integration at Maker Faire Bay Area 2016. The mod allows the user to access the inputs and output of the Arduino, in this case a Pololu A-Star 32U4, from within Minecraft. For the class this is all packaged nicely in the form of a laser cut controller. It has some LEDs, two joysticks, buttons, potentiometers, and a photosensor.

As you can see in the video below the break, it’s really cool. The kids have a great time with it too. For example, [John] showed them how they can attach their unique controller to a piston in the world. Since this piston can be controlled by them alone, they quickly figured out how to make secret safe rooms for their items.

Another troublesome discovery, was that the photo transistor on the controller set the light level in the game world by altering the time of day. Kids would occasionally get up and change the world from day to night, by turning the lights in the room on or off. A feature that has a certain appeal for any Minecraft player, is rigging one of the LEDs on the controller to change brightness depending on proximity to a creeper.

There’s a lot more to the library, which is available on GitHub. The kids (and adults) have a great time learning to link the real world with the world’s most accessible fantasy world creation kit.  Great work [John]!

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How To Keep An Unruly Dryer In Line

If necessity is the mother of invention, then inconvenience is its frustrating co-conspirator. Faced with a finicky dryer that would shut down mid-cycle with a barely audible beep if its load was uneven (leaving a soggy mass of laundry), [the0ry] decided to add the dryer to the Internet of Things so it could send them an email whenever it shut itself down.

After opening a thinger.io account, adding the soon-to-be device, and setting up the email notification process, [the0ry] combined the ESP8266 Development Board, a photosensitive resistor, and a 5V power supply on a mini breadboard. All that was left was to mount it on the dryer and direct the LDR (light-dependent resistor) to the machine’s door lock LED to trigger an email when it turned off — indicating the cycle had finished or terminated prematurely. A little tape ensured the LDR would only be tripped by the desired light source.

If you’re an apartment-dweller have WiFi in the wash area it would be awesome to see a battery-powered version you take with you. But in general this is a great hardware blueprint as many device have status LEDs that can be monitored in a similar way. If you want to keep the server in-house (literally in this case) check out the Minimal MQTT series [Elliot Williams] recently finished up. It uses a Raspberry Pi as the center server and an ESP8266 is one of the limitless examples of hardware that plays nicely with the protocol.

We love seeing hacks like this because not only does it conserve water and energy by reducing instances of rewashing, but it’s also a clever way to extend the life of an appliance and potentially save hundreds of dollars in replacing it. Add this to the bevvy of hacks that add convenience to one’s home — some of which produce delicious results.