+void DropField() {
+       UsbCommand c = {CMD_READER_ISO_14443a, {0, 0, 0}}; 
+       SendCommand(&c);
+}
+
+int ExchangeAPDU14a(uint8_t *datain, int datainlen, bool activateField, bool leaveSignalON, uint8_t *dataout, int maxdataoutlen, int *dataoutlen) {
+       uint16_t cmdc = 0;
+       
+       if (activateField) {
+               cmdc |= ISO14A_CONNECT | ISO14A_CLEAR_TRACE;
+       }
+       if (leaveSignalON)
+               cmdc |= ISO14A_NO_DISCONNECT;
+
+       // "Command APDU" length should be 5+255+1, but javacard's APDU buffer might be smaller - 133 bytes
+       // https://stackoverflow.com/questions/32994936/safe-max-java-card-apdu-data-command-and-respond-size
+       // here length USB_CMD_DATA_SIZE=512
+       // timeout must be authomatically set by "get ATS"
+       UsbCommand c = {CMD_READER_ISO_14443a, {ISO14A_APDU | cmdc, (datainlen & 0xFFFF), 0}}; 
+       memcpy(c.d.asBytes, datain, datainlen);
+       SendCommand(&c);
+       
+    uint8_t *recv;
+    UsbCommand resp;
+
+       if (activateField) {
+               if (!WaitForResponseTimeout(CMD_ACK, &resp, 1500)) {
+                       PrintAndLog("APDU ERROR: Proxmark connection timeout.");
+                       return 1;
+               }
+               if (resp.arg[0] != 1) {
+                       PrintAndLog("APDU ERROR: Proxmark error %d.", resp.arg[0]);
+                       return 1;
+               }
+       }
+
+    if (WaitForResponseTimeout(CMD_ACK, &resp, 1500)) {
+        recv = resp.d.asBytes;
+        int iLen = resp.arg[0];
+               
+               *dataoutlen = iLen - 2;
+               if (*dataoutlen < 0)
+                       *dataoutlen = 0;
+               
+               if (maxdataoutlen && *dataoutlen > maxdataoutlen) {
+                       PrintAndLog("APDU ERROR: Buffer too small(%d). Needs %d bytes", *dataoutlen, maxdataoutlen);
+                       return 2;
+               }
+               
+               memcpy(dataout, recv, *dataoutlen);
+               
+        if(!iLen) {
+                       PrintAndLog("APDU ERROR: No APDU response.");
+            return 1;
+               }
+
+               // check block TODO
+               if (iLen == -2) {
+                       PrintAndLog("APDU ERROR: Block type mismatch.");
+                       return 2;
+               }
+               
+               // CRC Check
+               if (iLen == -1) {
+                       PrintAndLog("APDU ERROR: ISO 14443A CRC error.");
+                       return 3;
+               }
+
+               // check apdu length
+               if (iLen < 4) {
+                       PrintAndLog("APDU ERROR: Small APDU response. Len=%d", iLen);
+                       return 2;
+               }
+               
+    } else {
+        PrintAndLog("APDU ERROR: Reply timeout.");
+               return 4;
+    }
+       
+       return 0;
+}
+
+// ISO14443-4. 7. Half-duplex block transmission protocol
+int CmdHF14AAPDU(const char *cmd) {
+       uint8_t data[USB_CMD_DATA_SIZE];
+       int datalen = 0;
+       bool activateField = false;
+       bool leaveSignalON = false;
+       bool decodeTLV = false;
+       
+       if (strlen(cmd) < 2) {
+               PrintAndLog("Usage: hf 14a apdu [-s] [-k] [-t] <APDU (hex)>");
+               PrintAndLog("Command sends an ISO 7816-4 APDU via ISO 14443-4 block transmission protocol (T=CL)");
+               PrintAndLog("       -s    activate field and select card");
+               PrintAndLog("       -k    leave the signal field ON after receive response");
+               PrintAndLog("       -t    executes TLV decoder if it possible. TODO!!!!");
+               return 0;
+       }
+
+       int cmdp = 0;
+       while(param_getchar(cmd, cmdp) != 0x00) {
+               char c = param_getchar(cmd, cmdp);
+               if ((c == '-') && (param_getlength(cmd, cmdp) == 2))
+                       switch (param_getchar_indx(cmd, 1, cmdp)) {
+                               case 's':
+                               case 'S':
+                                       activateField = true;
+                                       break;
+                               case 'k':
+                               case 'K':
+                                       leaveSignalON = true;
+                                       break;
+                               case 't':
+                               case 'T':
+                                       decodeTLV = true;
+                                       break;
+                               default:
+                                       PrintAndLog("Unknown parameter '%c'", param_getchar_indx(cmd, 1, cmdp));
+                                       return 1;
+                       }
+                       
+               if (isxdigit(c)) {
+                       // len = data + PCB(1b) + CRC(2b)
+                       switch(param_gethex_to_eol(cmd, cmdp, data, sizeof(data) - 1 - 2, &datalen)) {
+                       case 1:
+                               PrintAndLog("Invalid HEX value.");
+                               return 1;
+                       case 2:
+                               PrintAndLog("APDU too large.");
+                               return 1;
+                       case 3:
+                               PrintAndLog("Hex must have even number of digits.");
+                               return 1;
+                       }
+                       
+                       // we get all the hex to end of line with spaces
+                       break;
+               }
+               
+               cmdp++;
+       }
+
+       PrintAndLog(">>>>[%s%s%s] %s", activateField ? "sel ": "", leaveSignalON ? "keep ": "", decodeTLV ? "TLV": "", sprint_hex(data, datalen));
+       
+       int res = ExchangeAPDU14a(data, datalen, activateField, leaveSignalON, data, USB_CMD_DATA_SIZE, &datalen);
+
+       if (res)
+               return res;
+
+       PrintAndLog("<<<< %s", sprint_hex(data, datalen));
+       
+       PrintAndLog("APDU response: %02x %02x - %s", data[datalen - 2], data[datalen - 1], GetAPDUCodeDescription(data[datalen - 2], data[datalen - 1])); 
+
+       // TLV decoder
+       if (decodeTLV && datalen > 4) {
+               TLVPrintFromBuffer(data, datalen - 2);
+       }
+       
+       return 0;
+}