April 15th, 2008

RFID Security System

 RFID Security System final assembly

Designed to replace the antiquated mechanical push button locks on doors, this easy-to-use security system is built around the embedded RFID tags in student ID cards. Of-course any other RFID enabled card could be used, with modification to the source-code.

The system can store codes from up to 20 different ID cards in the ATmega32’s EEPROM but if you need a larger storing capacity an external EEPROM memory can be inserted with adjustments in the schematic and source code. I think its cool how things evolve, and instead of building an access system based on password, you can easily build this RFID system.

RFID Security System: [Download Project][View Project PDF]

 ATmega48/88/168 Development Board

This is versatile development board for AVR microcontrollers ATmega48/88/168. It is good for testing and debugging embedded programs. It has many built-in peripheries connected to microcontroller so you can use them without soldering. ATmega microcontrollers are produced by ATMEL and they include a lot of features: I/O, Timers, PWM generators, ADC, RS232, TWI, SPI, Analog Comparator, Oscillator, EEPROM These microcontrollers are very versatile, easy to program and easy to use. This is the reason why I like these microcontrollers and why I decided to make development board for them.

ATmega48/88/168 Development Board: [Via][Link]

March 5th, 2008

ATMega Control Board

ATMega Control Board picture

Powerful new ATMega Control Board, includes a pre-installed ATMega32 Atmel Microcontroller, running at 16MHz. This board is ideal for embedded control applications and robotic controllers. Easy to connect and interface with existing equipment, all ports are connected to headers and ADC connections are available using standard pcb terminals. Microcontroller can be programmed in-circuit using separate download unit, download software is included.

On-chip 32kbytes of Flash Program Memory and 2kBytes of RAM. 8 Channel 10-bit Analog to Digital Converter and 4 PWM channels. Programmable serial USART and SPI included within the microcontoller.

Board also includes sockets for a Real Time Clock (DS1307) with battery back-up socket, RS232 Communication (MAX232 included), EEPROM (24LCXX Series) and LCD connection including contrast trimpot. On-board buzzer and reset switch are also included. Power supply is +5V dc, via easy to connect pcb terminals.


  • ATMega32 Main Controller with 32kb of Flash Memory
  • All port pins wired to easy to connect headers
  • ADC Connections available at separate PCB Terminals
  • RS232 Computer Connection (MAX232)
  • Real Time Clock (DS1307 option)
  • EEPROM (24LCXX Series option)
  • LCD Port with Contrast Adjustment
  • Buzzer On-Board
  • Dimensions: Width 82mm, Height 82mm

ATMega Control Board : [Via]

 50 MHz frequency counter, voltage meter & SWR/PWR indicator

This is a successor of the PIC16C71 4-digit LED f-counter & V-meter. Some hard to find parts used in the previous version, which are out of production for some time, has been omitted. A rather early PIC16C71 has also been replaced by 28-pin device PIC16F876. The later is capable of driving 4 digit LED display in multiplexed mode while measuring frequency, power supply voltage as well as handle two analog inputs to display SWR/PWR signal strength in a bargraph manner. There is no need for external LED display driver chip as well as external data EEPROM since it is already implemented in PIC16F876. Reduction in the number of used chips also results in smaller dimensions of the counter compared to its predecessor.

In operating mode a push-button allows the user to choose between the frequency, bargraph or supply voltage to be displayed. The frequency display mode can also be changed with longer (>1s) push-button pressing. For example if the frequency to be displayed is 14.065.9 MHz the user will see on the four digit display either “065.9”, “4.065” or “14.06”. The default display mode after power-up can be changed in the set-up menu. The set-up menu is entered at power-up while holding the push-button pressed.

The production of Siemens’s (now Infineon’s) miniature 7 seg. LED HDN1077 displays in low current version (suffix O) was abandoned recently. Therefore I’ve designed another display PCBoard which suits the same f-counter base board but uses newer Agilent’s HDSP-U103 miniature 7 seg. LED displays. Their current consumption is even smaller. They need no more than 0,5mA per segment for acceptable brightness. Assuming that during normal operation in average only one half of the segments lights, the average current consumption of the counter is about 20mA. In power-save mode the consumption reduces to less than 10mA which is important in case of battery powered equipment.

The latest software version of the frequency counter is for radio-amateur and non-commercial use downloadable from this page for free. The PIC controller is in-circuit programmable if the MC34064 reset circuit is not soldered to the PCB. The instalation of this IC is strongly recommended after the frequency counter has been built and tested.
50 MHz frequency counter, voltage meter & SWR/PWR indicator
[VIA][Circuit Schematic]

Now this is a project to pay attention to. I dont know about you but i’ve always been a fan of scrolling text displays. This is cool. You can use it on pc casing moding, or anywhere else where you might want to add this nice effect. The text can be sent via RS232 interface from a computer, or it can be saved on a EEPROM memory. Fonts set of 256 different characters can also be programmed and mast be written to EEPROM before sending text to display. The author provides you with full info on building the project and also on the firmware.

Scrolling text display generated on 50×7 LED matrix with AVR AT 90S2313


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