File content as of revision 3:459a4f985a45:

#include "mbed.h"
#include "GT511C3.h"

Serial debug(USBTX,USBRX);

DigitalOut myled(LED1);
GT511C3 finger(p28,p27);

int Enroll(void)
{
    int EnrollID = 10;
    unsigned long Parameter = 0;
    unsigned short Response = 0;
    int sts = 0;

    debug.printf("EnrollStart\n");
    finger.CmosLed(1);

    while(1){
        debug.printf("CMD_EnrollStart\n");
        Parameter = EnrollID;
        sts = finger.SendRecv(GT511C3::CMD_EnrollStart,&Parameter,&Response);
        debug.printf("sts = %d,Response=0x%04x Parameter=0x%08lx\n",sts,Response,Parameter);
        if(sts != 0)
            return sts;
        if(Response != GT511C3::CMD_Ack)
            return -100;

        debug.printf("Remove finger\n");
        finger.WaitPress(0);

        while(1){
            debug.printf("Press finger to Enroll (1st)\n");
            finger.WaitPress(1);
            if(finger.Capture(1) == 0)
                break;
        }

        debug.printf("Remove finger\n");
        if(finger.Enroll_N(1) != 0)
            continue;
        finger.WaitPress(0);

        while(1){
            debug.printf("Press finger to Enroll (2nd)\n");
            finger.WaitPress(1);
            if(finger.Capture(1) == 0)
                break;
        }

        debug.printf("Remove finger\n");
        if(finger.Enroll_N(2) != 0)
            continue;
        finger.WaitPress(0);

        while(1){
            debug.printf("Press finger to Enroll (3rd)\n");
            finger.WaitPress(1);
            if(finger.Capture(1) == 0)
                break;
        }

        debug.printf("Remove finger\n");
        if(finger.Enroll_N(3) != 0)
            continue;
        finger.WaitPress(0);

        debug.printf("Enroll OK!\n");
        break;
    }
    return 0;
}

int main() {
    unsigned long Parameter;
    unsigned short Response;
    int sts = 0;
    int count = 0;
    int ispress;
    int ID;

    debug.format(8,Serial::None,1);
    debug.baud(115200);

    debug.printf("Init\n");
    finger.Init();
    debug.printf("Open\n");
    Parameter = 0;
    sts = finger.SendRecv(GT511C3::CMD_Open,&Parameter,&Response);
    debug.printf("sts = %d,Response=0x%04x\n",sts,Response);

    if(1){
        Enroll();
    }

    finger.CmosLed(1);
    while(1) {
        ispress = finger.IsPress();
        debug.printf("IsPressFinger=%d\n",ispress);
        if(ispress){
            if(finger.Capture(1) != 0)
                continue;
            ID = finger.Identify();
            debug.printf("ID = %d\n",ID); 
        }
#if 0
        myled = 1;
        wait(0.5);
        myled = 0;
        wait(0.5);
#endif
        count++;
    }
}