Atmel ATAK2270 - Manual (Page 8)

RFID Application Kit ATAK2270 User Manual 3-1
4871E–RFID–04/08
Section 3
Description of the Application Board System
3.1 System Overview
The ATAK2270 application board unit ( Figure 2-3 ) consists of a ready-to-run standard microcontroller
main board equipped with the Atmel AVR ® microcontroller ATmega8515L, combined with a piggybacked
antenna interface board containing the U2270B reader IC.
The following functionality is controlled by the AVR microcontroller:
„ Handling of the bi-directional data communication between the RS232 interface and the host PC
„ Execution of the read and write commands to be sent to the antenna interface
„ Decoding of the specific read data delivered by the antenna interface
The source program is written in C, and the compiled hex code is loaded in the 8-kByte Flash of the
microcontroller.
3.2 Power Supply
To operate the reader board, an external power supply in the range of DC 10V to 15V/200 mA has to be
connected to the jack, alternatively use the mains SMPS. A bridge rectifier placed at the connector input
is used for polarity independence.
3.3 Antenna Interface
The antenna interface ( Figure 2-2 ) is supplied and controlled by the main board via header pin X2/1. The
current power supply voltage is indicated by LED1, Power. To adapt a specific antenna coil to the reso-
nant frequency and the Q factor, the components CANT1/CANT2 and R14 (
Figure 2-2 ) can be changed.
For the antenna included in the kit, the parameters are matched as follows:
Resonant frequency: f
res
= 125 kHz ±1%, adjusted by CANT1/CANT2 with jumper 3 in
position dis
Whole antenna quality factor: Q = 20, adjusted by R14