Quickie USB Keyboard Device

There are a ton of applications that we use that can benefit from keyboard shortcuts, and we use ’em religiously. Indeed, there are some tasks that we do so often that they warrant their own physical button. And the only thing cooler than custom keyboards are custom keyboards that you’ve made yourself.

Which brings us to [Dan]’s four-button Cherry MX USB keypad. It’s not really all that much more than four keyswitch footprints and an AVR ATmega32u4, but that plus some software is all you really need. He programs the Arduino bootloader into the chip, and then he’s using the Arduino Leonardo keyboard libraries. Bam! Check out the video below.

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Presenting the Internet of Trash Cans !

This was gonna happen – sooner or later. [matthewhallberg] built a “Smart” trash can that is connected to the Internet and can be controlled by its own Android App. We’re not sure if the world needs it, but he wanted one and so built it. He started it out on a serious note, but quickly realized the fun part of this build – check out his funny Infomercial style video after the break.

trash_can_02The build itself is uncomplicated and can be replicated with ease. A servo motor helps flip the lid open and close. This is triggered by an ultrasonic ping sensor, which responds when someone waves a hand in front of the trash can. A second ping sensor helps inform the user when it is full and needs to be emptied. A Leonardo with the Idunio Yun shield helps connect the trash can to the internet. An mp3 shield connected to a set of powered computer speakers adds voice capability to the trash can, allowing it to play back pre-recorded sound clips. Finally, a Bluetooth module lets him connect it to an Android phone and the companion app controls the trash can remotely.

For the IoT side of things, [matthewhallberg] uses a Temboo account to send an email to the user when the trash can is full. The Arduino sketch, a header file to configure the Temboo account, and the Android application can all be downloaded from his blog. If this project inspires you, try building this awesome Robotic trash can which catches anything that you throw near it  or read the barcodes off the trash being thrown out and update the grocery list.

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Benchmarking USB transfer speeds


[Paul Stoffregen], creator of the Teensy series of microcontroller dev boards, noticed a lot of project driving huge LED arrays recently and decided to look into how fast microcontroller dev boards can receive data from a computer. More bits per second means more glowey LEDs, of course, so his benchmarking efforts are sure to be a hit with anyone planning some large-scale microcontroller projects.

The microcontrollers [Paul] tested included the Teensy 2.0, Teensy 3.0, the Leonardo and Due Arduinos, and the Fubarino Mini and Leaflabs Maple. These were tested in Linux ( Ubuntu 12.04 live CD ), OSX Lion, and Windows 7, all running on a 2012 MacBook Pro. When not considering the Teensy 2.0 and 3.0, the results of the tests were what you would expect: faster devices were able to receive more bytes per second.  When the Teensys were thrown into the mix, though, the results changed drastically. The Teensy 2.0, with the same microcontroller as the Arduino Leonardo, was able to outperform every board except for the Teensy 3.0.

[Paul] also took the effort to benchmark the different operating systems he used. Bottom line, if you’re transferring a lot of bytes at once, it really doesn’t matter which OS you’re using. For transferring small amounts of data, you may want to go with OS X. Windows is terrible for transferring single bytes; at one byte per transfer, Windows only manages 4kBps. With the same task, Linux and OS X manage about 53 and 860 (!) kBps, respectively.

So there you go. If you’re building a huge LED array, use a Teensy 3.0 with a MacBook. Of course [Paul] made all the code for his benchmarks open source, so feel free to replicate this experiment.

Simple to build programmable foot switches


Your hands do a lot of work between the keyboard and the mouse, why the heck are you letting your feet be so lazy? [Dossier van D.] is putting an end to the podiatric sloth. He built this set of three foot pedals which have gone through two versions of functionality.

The buttons themselves are made from a base plate of plywood with a smaller piece on top for each ‘key’. The two parts are separated with some foam carpet pad, with a tactile push button in between to register a click. The only thing we’d change about this is adding a couple of wooden spacers next to the switch so that accidentally sanding on a button doesn’t break that electronic component.

Originally each button was soldered to a gaming controller. This worked just fine using button mapping, but recently [Dossier] made the switch to using an Arduino Leonardo. This is a perfect choice. Unlike input devices made with older Arduino versions the Leonardo board can natively register as a keyboard, making it a snap to programmatically map any key to the switches.

If you like this project you should check out [Dossier’s] foot mouse as well.