Hackaday Prize Entry: Wirelessly Charged Self-Heating Coffee Mug

Many productive hackers bleed a dark ochre. The prevailing theory among a certain group of commenters is that they’re full of it, but it’s actually a healthy sign of a low blood content in the healthy hacker’s coffee stream. [Bharath] is among those who enjoy the caffeinated bean juice on a daily basis. However, he’d suffer from a terrible condition known as cold coffee. To combat this, he built an app-enabled, wirelessly chargeable, self-heating coffee mug.

We know that most hackers don’t start off planning to build objects with ridiculous feature lists, it just happens. Is there an alternate Murphy’s law for this? Any feature that can be added will? The project started off as some low ohm resistors attached to a rechargeable power bank. A insulated flask with a removable inner stainless steel lining was chosen. The resistors were fixed to the outside with a thermal epoxy.

However, how do we control the resistors? We don’t want to burn through our battery right away (which could end up more literally than one would like), so [Bharath] added a Linkit One microcontroller from Seeed Studio. With all this power at his disposal, it was natural to add Bluetooth, a temperature sensor, and app control to the cup.

After getting it all together, he realized that while the insides were perfectly isolated from the liquids held in the flask under normal use, the hole he’d have to cut to connect to the charging circuit would provide an unacceptable ingress point for water. To combat this he added the wireless charging functionality.

With his flask in hand, we’re sure the mood boost from not having to slog through the dregs of a cold container of coffee will produce a measureable improvement in productivity. Video after the break.

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Stealthy Mortar Board Unleashes Bling at Graduation Ceremony

Decorating graduation caps is often frowned upon by the administration but [Dan Barkus] is challenging his school authorities to keep from smiling when they see what he has in store. His build will dazzle the audience by mounting 1024 RGB LEDs in a 32×32 matrix on top of his cap, but hidden under the cap’s black cloth. When the LEDs are off he’s indistinguishable, and when he fires up the LEDs, shine through and put on a heck of a show. He can type messages on his phone to be displayed on the cap. He can even display images and animated GIFs.

LED array control components
LED array control components

The LED display is an Adafruit 32×32 RGB LED matrix panel.  To control the display, [Dan] uses a Teensy, a 32 bit ARM Cortex-M4 microcontroller board. Wireless communication is done via a JBtek HC-06 Bluetooth board.

The LED display can draw up to 4 amps at full white brightness so he picked up a USB battery with two output ports, one capable of 2.1 amps and the other 2.4 amps. He then hacked together a cable that has two USB connectors on one end, connected in parallel, and a DC jack on the other end. Altogether the battery bank is capable of up to 4.5 amps output combined out those two ports, meeting the LED display’s needs. The DC jack is plugged into the Teensy and all power goes through there.

One problem [Dan] had was that the Bluetooth module was booting up before the Teensy. It didn’t see the Teensy in time, causing the Bluetooth not to work. The solution he found is shown in the 2nd video embedded below. The fix powers the Bluetooth module separately, using a current limiting resistor and a capacitor to build up the voltage, delaying just long enough for the Teensy to win.

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Tiling your TV Remote

The Tile is a small Bluetooth chip, speaker, and enough battery for a year in a keychain format. If you lose your keys in the morning, simply use the app on your phone to find the keychain. If you lose your phone simply get out your second phone.

This planned obsolescence didn’t jive with [JM] when his Tile stopped being discoverable. He didn’t want to toss a gadget that had served him so well into the landfill. So, like any good hacker, he cracked its plastic case open.

The Tile itself is a really interesting product. The largest component is the battery which has tabs spot-welded to its surface. Attached to those is a well laid out board. [JM] points out the clever use of spring contacts to engage the piezo element for the speaker as a nice example of good design for manufacture.

The hack itself was pretty easy to complete. Some electrical tape and soldering was all it took to embed the tile into the remote. Now he can take out his phone and press a button to hear a forlorn beep coming from under the couch cushions.

Which Wireless Tech is Right For You?

It seems these days all the electronics projects are wireless in some form. Whether you choose WiFi, Bluetooth Classic, Bluetooth Low Energy, ZigBee, Z-Wave, Thread, NFC, RFID, Cell, IR, or even semaphore or carrier pigeon depends a lot on the constraints of your project. There are a lot of variables to consider, so here is a guide to help you navigate the choices and come to a conclusion about which to use in your project.

We can really quickly reduce options down to the appropriate tech with just a few questions.

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Add Bluetooth to a Cheap Electronic Lock

[James] works from home. His office is filled with objects that can be described with adjectives such as, “expensive,” and, “breakable.” His home, however, is filled with professional object-breakers known as children. To keep these two worlds from colliding, he installed a keypad lock on his office door. The potential side-effect of accidentally training his children to be master safe-crackers aside, the system seems to work so far.

However, being a hacker, the tedium of entering a passcode soon grew too heavy for him. Refusing to be a techno-peasant, he set out to improve his lock. The first step was to reverse engineer the device. The lock is divided into two halves, one has a keypad and handle, the other actually operates the lock mechanism. They are connected with a few wires. He hooked an oscilloscope to the most likely looking candidates, and looked at the data. It was puzzling at first, until he realized one was a wake-up signal, and the other was the data. He then hooked the wires up to a Bluetooth-enabled Arduino, and pressed buttons until he had all the serial commands the door lock used.

After that it was a software game. He wrote code for his phone and the Arduino to try out different techniques and work out bugs. Once he had that sorted, he polished the app and code until he reached his goal. All of the code is available on his GitHub.

Finally, through his own hands, he elevated himself from techno-peasant to wizard. He need but wave his pocket oracle over the magic box in front of his wizard’s lair, and he will be permitted entry. His wizardly trinkets secure from the resident orcs, until they too begin their study of magic.

Bluetooth Water Cannon Junk Build Shoots Into Our Hearts

We’ve seen a few remote controlled turret builds in the past, but this one from [Noel Geren] is pretty neat: it shoots water and uses Bluetooth Low Energy (BLE) for control. Check it out in action in the video below.

[Noel] used the guts of a Nerf Thunderstrike water gun for the firing mechanism, combined with a 3D-printed enclosure and a servo that rotates the turret top. The pump from the gun is connected to a simple relay that replaces the trigger. Both the relay and the servo are connected to an RFDuino with a servo shield, which is programmed to respond to simple commands to rotate and fire.

It’s a nice junk build, and [Noel] has released all of the files for download if you want to build your own. It would make a nice weekend build or a project to do with the kids.

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Minions Turn Your Keyboard into a Bluetooth Keyboard

Evil geniuses usually have the help of some anonymous henchmen or other accomplices, but for the rest of us these resources are usually out of reach. [Evan], on the other hand, is on his way to a helpful army of minions that will do his bidding: he recently built a USB-powered minion that turns a regular PS/2 mouse and keyboard into a Bluetooth mouse and keyboard.

[Evan] found his minion at a McDonald’s and took out essentially everything inside of it, using the minion as a case for all of the interesting bits. First he scavenged a PS/2 port from an old motherboard. An Arduino Nano is wired to an HC-05 Bluetooth chip to translate the signals from the PS/2 peripherals into Bluetooth. The HC-05 chip is a cheaper alternative to most other Bluetooth chips at around $3 vs. $40 for more traditional ones. The programming here is worth mentioning: [Evan] wrote a non-interrupt based and non-blocking PS/2 library for the Arduino that he open sourced which is the real jewel of this project.

Once all the wiring and programming is done [Evan] can turn essentially any old keyboard and mouse into something that’ll work on any modern device. He also put an NFC tag into the minion’s head so that all he has to do to connect the keyboard and mouse is to swipe his tablet or phone past the minion.

If you’re looking for an interesting case for your next project, this McDonald’s Minion toy seems to be pretty popular. PS/2 keyboards are apparently still everywhere, too, despite their obsolescence due to USB. But there are lots of other ways to get more use out of those, too.

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