The purpose of this diploma thesis is a door access control system based on lowcost components. This thesis was made on proposal of Elan Microelectronics, which provided most of the components used. In addition to the actual application an application note has been written. It exemplifies the possibilities of the different Elan products integrated in an complete system. The developed demo-application is controlled by a lowcost microcontroller from Elan.

To identify a user, RFID is being used. This technology is in use by already existing door access systems. As an additional authentication mechanism, a PIN needs to be entered through a touchpad. The user interface is defined by this touchpad, a dot matrix display as well as some LEDs.

The hardware concept was adapted especially according to the peculiarities of the peripheral components and is an essential part of the work. In doing so, the components have been connected over communication busses, such as SPI and I2C.

The components provided by Elan feature lots of implemented functions. However, some of the components provide strange communication interfaces, which affect the programming predominantly. Furthermore, they are poorly documented. This has made the integration complicated.

Significant for the realised functional range was the size of the code and data memory of the microcontroller, which provides only 8kB of ROM and 128Byte of RAM. A great deal of the functionalities couldn?t have been implemented in the final product. Therefore, it isn?t designed for the use in a productive environment.