Subject : Microcontroller and Embedded Programming

Topic : Embedded System-The Case Studies

Difficulty : Medium

Battery Operated Smart Card Reader

Smart cards have gained a lot of significance in recent days. Fig. 12.2 shows a block diagram of smart card reader implemented using the microcontroller 8051.

1. The various components that will be required as seen in the figure are: power supply, clock or oscillator circuit, watchdog timer, communication port like RS232, smart card reader along with its antenna, keyboard, LCD display, memory for program & data and the microcontroller.
2. The power supply is implemented using a transformer, followed by a rectifier and finally a regulator.
3. The clock circuit is implemented using the standard circuit prescribed by Intel for 8051. The crystal of 11.0592MHz is used so that the serial communication he implemented easily.
4. The interfacing of the 16 X 2 LCD is done. The various signals connected of the LCD display are power supply pins (i.e. Vcc and GND), the VEE pin (for intensity adjustment of LCD backlight), data pins (D0-D7), RS (to indicate a command or data to LCD), RW( to indicate read or write operation to 10D) and E(Enable pin to indicate latching of command or data).
5. The switches are connected as shown in the fig. 12.1. Whenever the switch is pressed a zero is obtained on the microcontroller port pin else a ‘1’ is obtained. This can be used to identify the switch pressed.
6. The watchdog timer will be used to keep a track that the microcontroller doesn’t hang. If the microcontroller hangs then the watchdog timer will reset the microcontroller and hence avoid it from abrupt behavior.
7. The RS232 communicate can be implemented easily using serial port of 8051.
8. The Memory is to be interfaced to 8051.