Electronic lock developed by Dim uses the Dallas i-Button DS1990 data carrier. I-Button transfers identification data via 1-wire protocol which only requires single data lead and ground. It carries unique 64-bit registration number which can serve as a key to unlock an electric door lock.

Control circuit is based on Atmega32 microcontroller which stores up to 20 key data plus master key in EEPROM memory and also assigns a person name to key ID which can be displayed on LCD while key is activated. Electronic lock can be configured via RS232 interface. Keys and persons can be assigned using PC windows screens. Project files are available in downloads page.

It is hard to say how this is convenient to use such key - maybe in some specific areas like event tracking, inventory marking. Of course it is probably more convenient to use RFID.

Martin Thomas has this nice tool called Evertool in his collection. It is a AVRISP/STK500 and Programmer/JTAG debugger on a single board. It is compatible with AVRStudio with firmware upgrade-ability. So always new devices are supported.

Evertool has following features:

• ISP Programmer compatible with Atmel AVRISP, with AVRStudio and avrdude accessibility;

• JTAG debugger compatible with Atmel JTAGICE, works with AVRStudio and AvaRice;

• All Atmel AVR devices supported with their AVRISP and JTAGICE.;

• Easy update of the programmer via RS232/serial port;

• Rescue clock generation to recover from wrong fuse-bit-settings;

• Simple hardware, standard parts;

Evertool uses bootloader which is free for non-commercial use. Download latest version from here. Project is very well documented. There are also simplified versions of programmer available like JTAG only debugger, or even Evertool-USB version suggestion. Thomas Martin also has a nice collection of microcontroller programming examples including WinAVR and WinARM which is supported by him.

Traffic warning system or so called TDDY(Traffic Data Display ) is a vehicle-mounted, receive-only traffic warning system designed by Dubravko Gacina. System may be used to minimize the risk of vehicle like like public buses, emergency response vehicles, cabs, delivery vehicles accidents. An ATmega128 microcontroller and a matrix of 512 bi-color LEDs organized as a map of the Los Angeles freeways comprise the system.

Collisions between emergency vehicles and other vehicles are common events. Many of these collisions occur at inter-sections. Public vehicles approaching at 90 degrees to the direction of travel of emergency vehicles are very difficult to see. Sensors mounted on the vehicle could alert emergency vehicle drivers of approaching cross traffic. In such a scenario, sensors sends information to some sort of dispatching center which process incoming data and, in return, sends data to interested parties in form of positional information to traffic warning devices mounted in vehicles.

This design presents an early implementation of traffic warning device. Conventionally, it uses server software hosted on PC and pager which serves as client to display position of vehicles on city map. You can download project files here .

Want to learn how to generate sound effect or simply play melodies on your microcontroller project? You should read nice series of articles in uchobby where is deep analysis made on how sound can be generated by using limited resources.

This time he describes Bit-Banging Sound generating technique with source code example. Bit-bang is simple output toggling at desired frequency. To play a musical note, specific frequencies are needed that are played for a specific amount of time. About other sound generating techniques and comparison read here. Further you can find simple experiments that leads to nice sound wave generation with Arduino board.

SparkFun team have made a huge interactive Tetris game. This is really impressive piece of art made of 16 Atmega8 microcontrollers, 720 LEDs and 240 buttons. Game can be controlled by touching buttons directly on frame(similar to touch screen).

The Tetris board is 10×20 cells and each cell lights up 1 of 7 different block colors. Separate button pads are 4×4 and there are 15 of them, so total array is of 12×20 buttons. There is RGB LED placed behind each button so it is possible to light any button with any color. Can imagine what processing power is needed to update all picture and read all button state. This is why whole project was break up in pieces of 4×4 button pads with separate microcontrollers accessed via SPI interface. Project is really challenging but satisfaction is 100% guaranteed. They provide all schematics and firmwares if somebody wants to give a try.