从GPIO传输智能卡数据

Question

我正在尝试从C8051微控制器访问智能卡。我可以在重置后从智能卡接收ATR。当我尝试从同一条GPIO线发送命令时，智能卡没有响应。

在这个程序中，我正在使用基于中断的技术，当GPIO的信号变为低电平时，触发中断，因此我们开始接收数据。但是当我发送命令时，这个中断没有被触发。

void transmit_smart_data(void)
{
    char j=0,parity,k=0,y=0,q=0;
    puts("smart\n\r");
    IE_EX0=0;   //disabling interrupt
    P0MDIN |=P0_B7;
    P0MDOUT|=P0_B7;
    while(valid_tx=getchar(),valid_tx!='b')                 //last character of the command is 'a'(asumption)
    {
        valid_data[j]=valid_tx;
    }
    valid_data[j]='z';
    puts("valid\n\r");
       j=0;
        while(valid_data[j]!='z')
        {
           parity=parity_data(valid_data[j]);
           putchar(parity);
             P0_B7=0;
             TMR2RL  = -4550;                  // Init reload values
             TMR2    = TMR2RL;
             TMR2CN_TR2 = 1;
            while(!TMR2CN_TF2H);                   // Wait for overflow
            TMR2CN_TF2H = 0;
            while(k<8)
            {
        if(((valid_data[j])&(1<<q))!=0)  //sending bitwise bit data
        {
           //putchar('1');
            P0_B7=1;
            TMR2CN_TR2 = 1;
            while (!TMR2CN_TF2H);                   // Wait for overflow
            TMR2CN_TF2H = 0;//TMR2CN_TR2 = 0;
            k++;q++;
        }
        else
                {// putchar('0');
                                P0_B7=0;TMR2CN_TR2 = 1;
                                while (!TMR2CN_TF2H);                   // Wait for overflow
                                TMR2CN_TF2H = 0;//TMR2CN_TR2 = 0;
                                k++;q++;
                                    }
                }

            if(parity!=0)
             {
                //putchar('1');
                P0_B7=1;
                    TMR2CN_TR2 = 1;
                    while (!TMR2CN_TF2H);                   // Wait for overflow
                                        TMR2CN_TF2H = 0;//TMR2CN_TR2 = 0;
                                // s
                    }
                else
                {
                    //putchar('0');
                    P0_B7=0;
                    TMR2CN_TR2 = 1;
                    while (!TMR2CN_TF2H);                   // Wait for overflow
                    TMR2CN_TF2H = 0;
                }

                                               P0_B7=1;
                                                TMR2RL  = -(4550*3);                  // Init reload values
                                                TMR2    = TMR2RL;                   // Init Timer2 with reload value
                                                 TMR2CN_TR2 = 1;
                                                 while (!TMR2CN_TF2H);                   // Wait for overflow
                                                TMR2CN_TF2H = 0;
                                                    j++;q=0;k=0;


        }
        puts("data");
        TCON_IE0=0;
                P0MDIN  |= (1<<7);
                P0_B2=1;
        // Configure P0.0 as analog input.
      //  puts("data");
                IE_EX0=1;
}