Hackaday Links: Sunday, April 28th, 2013


Another week has gone by and we hope you’ve been happily hacking away in your underground lairs. If not, here’s some inspiration that didn’t quite make it to the front page this week:

[Razr] used a CFL ballast to replace the mechanical one in his fluorescent tube light fixture.

To make the drawers of his workbench more awesome [Rhys] used the faceplates from some servers.

This week saw some changes in the hobby PCB market. Looks like BatchPCB is being sold to OSH Park starting May 1st. [Thanks Brad]

[Rich Olson] shouldn’t have any trouble getting out of bed now that his alarm clock literally shreds cash if he doesn’t shut it off.

We faced the same problem as [Kremmel] when we first got a Raspberry Pi, no USB keyboard. We bought one but he simply hacked his laptop to work. [Thanks Roth]

You may remember that post about a self-propelled snowboard. Here’s a similar project that uses a screw-drive system.

And finally, if you need help reading a quadrature encoder from a microcontroller this lengthy technical post is the place to look.

Typewriter is USB keyboard, also awesome

If you’re a brooding author putting the finishing touches on the next Great American Novel™ while sipping a latte in Starbucks, a MacBook is far too common to impress uncultured proles guzzling caramel macchiatos. No, to impress the next [Joyce] or [T. S. Eliot] sitting at the table next to you, you’ll need something much more hip, like a kit to turn a typewriter into a USB keyboard.

This kit to turn an old Underwood into a USB keyboard comes from the drawing board of [Jack Zylkin], member of Philly hackerspace Hive 76. [Jack] managed to make the process of turning an old typewriter into a keyboard a relatively painless process.

[Jack] created a sensor board loaded up with 74HC595 shift registers that easily mounts to the frame of just about any typewriter. When a key on the typewriter is struck, the mechanical levers strike metal strips soldered to the sensor board. An ATMega microcontroller records these keypresses and sends them over a USB port just like any other USB keyboard.

Modifying a typewriter into a USB keyboard is one of those projects we’d dread; you’d think there would be far too much futzing about with a lot of small electrical contacts and dirty mechanical devices. [Jack] actually managed to put together a very nice kit to turn a typewriter into a keyboard here.

You can pick up a kit over at [Jack]‘s etsy store, but doing the same thing with a bit of perf board isn’t out of the question. Awesome video after the break.

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Remote-controlled USB switch

When [beerninja] wanted to swap his USB keyboard from one game console to another without mucking about with wires, he asked the Hack A Day forums for some help. [Meseta] (AKA [UAirLtd]) came to the rescue and built [beerninja] a remote-controlled USB switch.

After opening up a no-name USB switch, [Meseta] discovered that the switching is done with simple relays and switches. A hugely overpowered Forebrain ARM dev board was used to pull each switch low for a few hundred milliseconds to switch the output USB port.

For the infrared remote control, [Meseta] dug into Lady Ada’s IR sensor tutorial and decoded buttons 1 through 4 on a Sky TV remote. Each button from one to four corresponds to the buttons on the USB sharing switch. The ’0′ button was also decoded as a convenience to put the Forebrain into its reprogramming mode. After drilling a small hole for the IR receiver, the finished project was stuffed back into the original steel enclosure.

Check out the video of the switch in action after the break.

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Driving USB peripherals with Arduino


Circuits@Home have managed to host a USB keyboard with an Arduino and display the keyboard inputs on a character LCD. This uses the USB host shield we covered in August. That host shield includes a MAX3421 which is used here to drive the character LCD.

The control code for the keyboard ends up being fairly simple. The keyboard is polled for entries. The HID input is then examined and converted to ASCII codes for use with the LCD screen. This could make for an excellent controller or debugger for embedded systems. The Arduino, shield, and LCD could be integrated into the keyboard itself with an I/O port for connecting to your project. Commands can be typed out and sent through the I/O port when enter is pressed, with feedback displayed on the screen.

The example code provided with this project lays out the framework for hosting peripherals. We’re looking forward to more projects, and code libraries that take advantage of this new functionality.