QuickBuilder - Projects: Serial I2C Smart Card Reader/Writter

Introduction
This project demonstrates how to operate the 'I2C card reader (ST14C02)' using a serial interface.

Operation
See application code below. When a 256-byte I2C memory card such as the ST Microelectronics ST14C02 is inserted in to the card socket the string "/E01" is transmitted out of the serial port, when the card is removed the string "/E00" is transmitted.

The card reader/writer responds to the following commands. All commands are appended with a carriage return.

READ
"/Raa" Read 4-bytes of data from hexadecimal address aa.
Example: Read 4-bytes of data from address 80hex.
Command: "/R80"
Response: "/Rdddddddd" where dd is hexadecimal data

WRITE
"/Waadddddddd" Write 4-bytes of data to hexadecimal address aa.
Example: Write 4-bytes of data (1,2,3,4) to address 00hex
Command: "/W0001020304"
Response: "/W"

QUERY
"/Q" Query card status.
Example: Get card status
Command: "/Q"
Response: "/Qdd" where dd=00 card absent, dd=01 card present

Application code
Below is the application code for this project. To use it, select and copy (ctr-insert) the code below, paste it into a text editor and save as a 'C' file in your working directory. You may also need to change the build output path using 'Project | Options'

 
///////////////////////////////////////////////////////////////////////
////                           AI2CCARD.C                          ////
////                                                               ////
////  Demonstrates the 'I2C card reader (ST14C02)' sub-circuit.    ////
////  When an ST140 is inserted into the card socket the           ////
////  string "/E01" is sent and "/E00" when the card is removed.   ////
////  "/Waadddddddd" writes data to the card where aa is the       ////
////  address in hex and DD are four data bytes to write.          ////
////  "/Raa" reads four bytes of data from address aa.             ////
////  All commands and responses are appended with a carriage      ////
////  return.                                                      ////
////                                                               ////
////  This program is an example of how your application code is   ////
////  is organised. Note the #include "i2ccard.inc", this include  ////
////  file was generated by QuickBuilder and contains all          ////
////  dirver code.                                                 ////
////                                                               ////
////  This demo is intended for  a PIC16F84                        ////
////  Compile using CCS 'C'  visit www.quickbuilder.co.uk/qb/ccs   ////
///////////////////////////////////////////////////////////////////////
#include <16f84.H>

#fuses   XT,NOPROTECT,NOWDT

#case

#include "i2ccard.inc"


// Comms vars
int     RxCmd = 0;
int     RxData[8];
int     RxIP=0;
int     RxState = 0;

void BlinkLED(void) {
    LED_1OFF();
    delay_ms(100);
    LED_1ON();
}

int HexToNibble( char c ) {
    if ( (c >= '0') && (c <= '9') )
        return c-'0';
    else if ( (c >= 'A') && (c <= 'F') )
        return c-('A'-0x0a);
    else
        return 0;
}

int GetCommand( void ) {
    int c,d,n;
    

    if ( RS232_1INCOMING()==0 )     // incomming char
        return 0;

    c = RS232_1IN();
    if (c=='/')
        RxState = 0;    

    switch ( RxState ) {
        case 0 : // command start
            RxIP = 0;
            n = 0;
            RxCmd = RS232_1IN();        // get command char
            RxState = 1;
            break;
        case 1 : // get data
            if (c==0x0d) {              // end of commad hex data
                RxState = 0;
                return 1;
            } else {                    // get data
                c = HexToNibble( c);
                if ( !bit_test(n,0) ) { // high nibble
                    RxData[ RxIP ] = c<<4;
                    n++;
                } else {                // low nibble
                    RxData[ RxIP] |= c;
                    RxIP++;             // inc index and wrap
                    RxIP &=0x7;
                    n++;
                }
            }
            break;
        default: // illegal state
            RxState = 0;
    }
    return 0;
}

void DoCommand( void ) {
    int addr,i,d;

    BlinkLED();
    switch (RxCmd) {
        case 'R' :  // read 4-bytes from card
            printf(RS232_1OUT,"/R");
            for (i=0 ; i<4; i++) {
                d = ST1402_1READ( RxData[0]++ );
                printf(RS232_1OUT,"%02X", d);
            }
            printf(RS232_1OUT,"\n");
            break;
        case 'W' :  // write 4-bytes to card 
            for (i=1 ; i<5; i++) {
                ST1402_1WRITE( RxData[0]++,RxData[i] );
            }
            printf(RS232_1OUT,"/W\n");
            break;
        case 'Q' : // query card status
            if ( ST1402_1PRESENT() )    // card present
                printf(RS232_1OUT,"/Q01\n");
            else                        // card not present
                printf(RS232_1OUT,"/Q00\n");
            break;

        default:    // unknown command
            printf(RS232_1OUT,"/?\n");        
        }
    RxCmd = 0;

}

void DoCard( void ) {
    static int1 CardPresent=0;

    if (ST1402_1PRESENT() ) {
        if (!CardPresent) {
            BlinkLED();
            printf(RS232_1OUT,"/E01\n");
        }
        CardPresent = 1;
    } else {
        if (CardPresent) {
            BlinkLED();
            printf(RS232_1OUT,"/E00\n");
        }
        CardPresent = 0;
    }

}

main() {
    INIT_SUB_CIRCUITS();
    BlinkLED();

    while(1) {
        if ( GetCommand() )
            DoCommand();
        DoCard();
    }
}