1. I love it! How does one make the Attiny show up as an HID device though? I suppose google is my friend, and I'll go look now!

Posted at 11:00PM on Apr 1st 2008 by Bullwinkle Jones

2. hahahaha that's awesome!!

Posted at 11:03PM on Apr 1st 2008 by andrew

3. bull: he links to Easylogger which includes the source code.

The library used can be found here: http://www.obdev.at/products/avrusb/index.html

Software implementation of USB 1.1

Posted at 11:17PM on Apr 1st 2008 by jproach

4. wow i never would have guessed you could do USB emulation on a tiny45. thats pritty neat in itself.

Posted at 11:28PM on Apr 1st 2008 by chupa

5. thanks...it was really a spur of the moment thing, as you can see by the messy construction. but really easy to put together. obdev's avr-usb works great. it only took a little while to dig into the easylogger code and disable the adc and button detection parts, randomize the timing, and have it only send scancode 57 (caps lock). if you want to do something similar, just make sure a report with keystroke is followed by an empty report. i thought of a few other interesting variations, trying to keep focus on "harmless" stuff. sending a "volume up" keypress is easy...could be quite effective. holding down shift for a while would be more subtle than caps lock. how about pressing "F1" every couple minutes to be extra helpful. mouse wiggles can have bad consequences, but should be highly entertaining on a gaming machine. wheel of death: mouse right at high speed, click mouse1 button at 10hz and roll mouse wheel for weapon select. anyway i'll put some schematics and pcb and code up later for those of you who want to try this. the eagle part for the board-edge USB connector could be handy too, i'll make it available.

Posted at 11:53PM on Apr 1st 2008 by macegr

6. could you build it into a hub?

Posted at 11:54PM on Apr 1st 2008 by ryan

7. That's hackadaylarious. April fools indeed!

Posted at 5:48AM on Apr 2nd 2008 by John

8. Ha Ha good one !!! A true hackers april fools joke. :)

Posted at 8:29AM on Apr 2nd 2008 by DigitalMind

9. deliciously evil....

I'm making several of these to torture those around me with.

Posted at 10:52AM on Apr 2nd 2008 by fartface

10. ryan:
If its a proper usb 1.1 client, that would mean you would have have to take up one of the ports. Or, the alternative is you jam a second usb hub inside the first, but then your wasting 3 ports.

It can be done though. You could even put a hub inside the keyboard itself, along with this thing, so that they would never figure out what was going on.

Posted at 10:57AM on Apr 2nd 2008 by atrain

11. an even sneakier variation would use a 5 pin jack with the same layout as most spare USB pin headers on motherboards. putting in inside anything other than the computer itself means that replacing that part would solve the problem. however it still means taking apart the computer. using the tssop or mlf version of the attiny45, and a double sided pcb, it should be possible to put the whole circuit on the opposite side of the pcb from the contact strips. glue on hollowed plastic spacer or cast on some epoxy, and you have a little device that fits entirely inside the usb jack.

Posted at 12:44PM on Apr 2nd 2008 by macegr

12. This makes me really happy! I use AVRs in my projects all the time and i've been wanting to add USB support to projects! The linked easylogger projects looks like the perfect starting place, thanks Hack a Day! :)
-Taylor

Posted at 2:33PM on Apr 2nd 2008 by Taylor Alexander

13. @10
If you're going to put it in a keyboard, why not just have it short the "caps lock" key every so often, instead of dealing with the USB interface?

Posted at 8:20PM on Apr 2nd 2008 by daler

14. That is great, you need a USB header version for inside the case, possibly mounted on a CD-Rom audio cable.

They would never find it, you could tuck it anywhere.

Posted at 11:24PM on Apr 2nd 2008 by Miles

15. All it needs is a radio frequency receiver for the trickster to trigger on and off at the appropriate moment if in a group of computer uses.

Posted at 2:12PM on Apr 3rd 2008 by Mark p.s.

16. oh, very cool. and i guess it could be reflashed into being something useful for the rest of the year.

nice.

Posted at 2:16PM on Apr 3rd 2008 by jim

17. @13: perhaps to prevent ppl trying a different keyboard.

I guess with this, you would see the caps lock light blink. Or it could be pulsed.
It could make it so that it stops bugging when you press the scroll lock key and then say there is no problem :)
(The 3 lights will propagate to other keyboard devices)

Posted at 2:57AM on Apr 4th 2008 by DarkFader

18. This inspired me to write a software version. I wrote an app that randomly (30% of the time) toggles caps lock when you press left shift. I figured that way it would be extra annoying because people would think they miss clicked. Anyways, you can get the app at my site officewarfare.net.

Posted at 11:52PM on Apr 4th 2008 by Josh