-       uint8_t pos_td = 1;
-       if ( (card_ptr->atr[1] & 0x10) == 0x10) pos_td++;
-       if ( (card_ptr->atr[1] & 0x20) == 0x20) pos_td++;
-       if ( (card_ptr->atr[1] & 0x40) == 0x40) pos_td++;
-       
-       // T0 indicate presence T=0 vs T=1.  T=1 has checksum TCK
-       if ( (card_ptr->atr[1] & 0x80) == 0x80) {
-               
-               pos_td++;
-       
-               // 1 == T1 ,  presence of checksum TCK
-               if ( (card_ptr->atr[pos_td] & 0x01) == 0x01) {
-                       uint8_t chksum = 0;
-                       // xor property.  will be zero when xored with chksum.
-                       for (uint8_t i = 1; i < len; ++i)
-                               chksum ^= card_ptr->atr[i];
-                       if ( chksum ) {
-                               if ( MF_DBGLEVEL > 2) DbpString("Wrong ATR checksum");
-                       }
-               }
-       }
-