2.1 IC card and deck
X76F100 128 × 8 bits for the confidentiality of the serial FLASH E2PROM, which read and write passwords passwords are 64 bits. Figure 2 Smart Card Smart Card package for the pin map. The chip is packaged in a card, insert the card in the deck IC card reader, the reader can read and write it to achieve encryption, inquiries, deposits, withdrawals and other functions.
IC card connector has 8 pins, when X76F100Y inserted, just with these pins. There are also two fixed end, where a fixed-side with the deck on a spring connected to the equivalent of two contacts and a normally closed reed switch. When the card is not inserted, the reed is closed, P3.2 pin is held low; when the card is inserted, the reed was the top open, P3.2 pin goes high. When the microcontroller detects P3.2 pin goes high, so X76F100 by the RST pin P1.3 goes high, it is reset.
SCM LG’s GMS97C52. It has 8K bytes of ROM, 256 bytes of RAM and 32 I / O ports, P1 port and serial device X25045 and X76F100 connection, P0, P2 ports for keyboard and display, P3 for the mouth P3.2 Detection of IC card is inserted, and the remaining seven ports, can be used for other functions expanded.
2.3 Supervisory Circuit
X25045 chip control circuit, which includes watchdog timers, voltage monitoring circuit and the E2PROM memory. Its function is to: generate the power-down when GMS97C52 RESET signal; watchdog to monitor the system and prevent crashes.
2.4 Keyboard Circuit
For convenience, the keyboard interface circuit with the I / O port implementation, which is 4 × 4 structure, 16 keys. Where the number keys 11, function keys 4, the Enter key a.
Numeric keys: 0,1,2,3,4,5,6,7,8,9, ? (backspace).
Function keys: query? , Storage, withdrawal -, change the password *.
Query? : Users can search by reading the code amount stored in the card.
Deposit: users can write the password into the card section.
Teller -: user password by writing to withdraw the money from the card.
Change Password *: Read password and write into the password change. For convenience, let him study the password for a password and write
To, press the password will also change read and write password.
Enter: 8-bit password or access shall enter the complete number of confirmed and completed the new password confirmation.
2.5 shows the circuit
LED display shows some use, but also with the I / O port implementation. For system status, enter the password or the amount you want to access and debug information.
As GMS97C52 drive current is limited, at P0, P2 port plus inverter SN74F04, increased drive capability. It inhaled current 64mA, the output current is 15mA, can guarantee the required sink Choice.