The Magical Mood Rock

Have you ever wondered that you can express your emotion through a rock? Ok, it might sound a little bit ridiculous, but isn’t everything possible, especially in this bizarre 21st century?

Well, some of you here might have heard this method before, but have you consider to build a magical Mood Rock?

It isn’t too hard to find the alabaster rock, where you can easily find it at the art stores.

The project is very simple. It’s fully based on the AVR-USB, it would be a cool experience to control the color from the PC with the AVR-USB microcontroller. The reason why AVR-USB is the best option, as it can easily handle the USB protocol in firmware and doesn’t need any additional ICs at all!

By the way, you should restore the bit-bang SPI, if you discovered that the SPI on the AVR were stop working. The cable is an ISP programming interface for the AVR.

In order to stick the AVR-USB microcontroller below the rock, you have to use a masonry bit to drill several holes in the bottom of the rock. Don’t forget to use a hammer and chisel to finish enlarging the space as well.

Share printer while computer is off

This is great idea that came up to Serasidis Vasilis. And for sure this is great solution when you share printer or other USB device from one computer to another. The problem is that sharing computer has to always on in order to be able to share the device.

So why not to use this USB switch that enables sharing USB devices when sharing computer is OFF. Device is quite simple – software based ATtiny2313 USB controller which communicates with one of two PC’s that have proper drivers installed and control programs started. USB switching is done via relays that won’t affect USB signal quality. Project description is in Greek language, so why not to use an online translator.

AVR based generic infrared transceiver

The idea of this universal IR remote transceiver (code name unzap) came from famous TV-B-Gone universal TV-off remote.


Remote control can be used to turn off any TV on your way. The board is small but includes an Atmega168, a USB port, a 2MB Atmel data flash (for storing all sorts of codes), a learning mechanism (which can detect the correct carrier frequency), four buttons (selecting transmitter and learning mode, enable USB, …) and four powerful IR LEDs.

One-hand wearable keyboard with USB interface

The latest keyboard version is an evolution of older one which was based on ATtiny2313 and could be connected to PC via PS/2 and was based on Attiny2313 microcontroller. Latest wearable keyboard is ported to at90usbkey demo board and can be connected to PC via USB.


Keyboard is able to produce all usual characters with few keys that are pressed in groups. It may be convenient to use it on special conditions like for portable computers, palmtops and so on. If you want to study it more John W. McKown provides project files and compiled firmware for free.