我想问一下RC522 这块RF 芯片能不能实现有卡来了产生一个中断，然后通知 MCU?我看到的例程基本上是采用查询的方式，不停地查找，我想用中断的方式操作，再则我配置了中断寄存器，不知道咋的就是外部中断引脚没有信号呀，一直是低电平，谁能给我个指导，高了好了没出来，下面是 RC522的寄存器配置。

char M500PcdConfigISOType(unsigned char type) { char status;    if (type == 'A')                     //ISO14443_A    {        ClearBitMask(Status2Reg,0x08);
      //WriteRawRC(CommandReg,0x20);    //as default  0x20         WriteRawRC(ComIEnReg,0x7f);      //as default 0x80        status = ReadRawRC(ComIEnReg);       WriteRawRC(DivIEnReg,0x80);       //as default 0x00 status = ReadRawRC(DivIEnReg); WriteRawRC(ComIrqReg,0x7f);      //as default 0x04 status = ReadRawRC(ComIrqReg); //WriteRawRC(DivIrqReg,0x0);      //as default 0x00 WriteRawRC(Status2Reg,0x0); //80    //trun off temperature sensor status = ReadRawRC(Status2Reg); WriteRawRC(WaterLevelReg,0x08);  //as default 0x08 status = ReadRawRC(WaterLevelReg);       WriteRawRC(ControlReg,0x10);     //as default 0x10 timer on/off status = ReadRawRC(ControlReg); //WriteRawRC(CollReg,0x80);     //as default
      WriteRawRC(ModeReg,0x3D); //3F    ---TxWaitRF bit status  = ReadRawRC(ModeReg);
       WriteRawRC(RxSelReg,0x86);//84  //      WriteRawRC(RxThresholdReg,0x84);//as default  //      WriteRawRC(DemodReg,0x4D);      //as default
 //      WriteRawRC(ModWidthReg,0x13);//26        WriteRawRC(RFCfgReg,0x7F);   //4F /*   WriteRawRC(GsNReg,0x88);        //as default???    WriteRawRC(CWGsCfgReg,0x20);    //as default???        WriteRawRC(ModGsCfgReg,0x20);   //as default??? */      WriteRawRC(TReloadRegL,30);//tmoLength);// TReloadVal = 'h6a =tmoLength(dec)     WriteRawRC(TReloadRegH,0);      WriteRawRC(TModeReg,0x8D);    WriteRawRC(TPrescalerReg,0x3E);    
  //     PcdSetTmo(106);    delay_10ms(1);        cdAntennaOn();    }    else  { //return -1; return 2; }        return MI_OK; }