diff --git a/sonoff/language/bg-BG.h b/sonoff/language/bg-BG.h
index a490f8e6e..dec628ae1 100644
--- a/sonoff/language/bg-BG.h
+++ b/sonoff/language/bg-BG.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/cs-CZ.h b/sonoff/language/cs-CZ.h
index b16ccf37f..d6c73baa9 100644
--- a/sonoff/language/cs-CZ.h
+++ b/sonoff/language/cs-CZ.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/de-DE.h b/sonoff/language/de-DE.h
index 8ad86d173..a9d85ba3c 100644
--- a/sonoff/language/de-DE.h
+++ b/sonoff/language/de-DE.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/el-GR.h b/sonoff/language/el-GR.h
index f5f281ca4..b6b9dfa9d 100644
--- a/sonoff/language/el-GR.h
+++ b/sonoff/language/el-GR.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/en-GB.h b/sonoff/language/en-GB.h
index 7c03e76f4..0a85d6a8b 100644
--- a/sonoff/language/en-GB.h
+++ b/sonoff/language/en-GB.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/es-AR.h b/sonoff/language/es-AR.h
index 73ec924c8..4503c4e57 100644
--- a/sonoff/language/es-AR.h
+++ b/sonoff/language/es-AR.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/fr-FR.h b/sonoff/language/fr-FR.h
index 09b7ef831..89a863810 100644
--- a/sonoff/language/fr-FR.h
+++ b/sonoff/language/fr-FR.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/he-HE.h b/sonoff/language/he-HE.h
index 64e6aeae3..7e2deacab 100644
--- a/sonoff/language/he-HE.h
+++ b/sonoff/language/he-HE.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/hu-HU.h b/sonoff/language/hu-HU.h
index 6a6a21020..a7db58513 100644
--- a/sonoff/language/hu-HU.h
+++ b/sonoff/language/hu-HU.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/it-IT.h b/sonoff/language/it-IT.h
index 145b6064c..a5ffca743 100644
--- a/sonoff/language/it-IT.h
+++ b/sonoff/language/it-IT.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/nl-NL.h b/sonoff/language/nl-NL.h
index cef56fb2e..773442714 100644
--- a/sonoff/language/nl-NL.h
+++ b/sonoff/language/nl-NL.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/pl-PL.h b/sonoff/language/pl-PL.h
index dba0726e4..63a15c5a5 100644
--- a/sonoff/language/pl-PL.h
+++ b/sonoff/language/pl-PL.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/pt-BR.h b/sonoff/language/pt-BR.h
index f8d037e83..1b0c34b16 100644
--- a/sonoff/language/pt-BR.h
+++ b/sonoff/language/pt-BR.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/pt-PT.h b/sonoff/language/pt-PT.h
index aeed10329..b969449d2 100644
--- a/sonoff/language/pt-PT.h
+++ b/sonoff/language/pt-PT.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/ru-RU.h b/sonoff/language/ru-RU.h
index aaa457ec7..b2ad0a1d8 100644
--- a/sonoff/language/ru-RU.h
+++ b/sonoff/language/ru-RU.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "А"
diff --git a/sonoff/language/sk-SK.h b/sonoff/language/sk-SK.h
index e1ecafd63..49430c31e 100644
--- a/sonoff/language/sk-SK.h
+++ b/sonoff/language/sk-SK.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/sv-SE.h b/sonoff/language/sv-SE.h
index 5a7934d71..61ab33b57 100644
--- a/sonoff/language/sv-SE.h
+++ b/sonoff/language/sv-SE.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/tr-TR.h b/sonoff/language/tr-TR.h
index 344e65b58..cfad17ca0 100755
--- a/sonoff/language/tr-TR.h
+++ b/sonoff/language/tr-TR.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "A"
diff --git a/sonoff/language/uk-UK.h b/sonoff/language/uk-UK.h
index be8f0530a..ce72f093f 100644
--- a/sonoff/language/uk-UK.h
+++ b/sonoff/language/uk-UK.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "А"
diff --git a/sonoff/language/zh-CN.h b/sonoff/language/zh-CN.h
index fbdc82207..a022f7939 100644
--- a/sonoff/language/zh-CN.h
+++ b/sonoff/language/zh-CN.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "安"
diff --git a/sonoff/language/zh-TW.h b/sonoff/language/zh-TW.h
index 008c33a10..06274c41b 100644
--- a/sonoff/language/zh-TW.h
+++ b/sonoff/language/zh-TW.h
@@ -553,6 +553,8 @@
 #define D_SENSOR_MCP39F5_RST   "MCP39F5 Rst"
 #define D_SENSOR_CSE7766_TX    "CSE7766 Tx"
 #define D_SENSOR_CSE7766_RX    "CSE7766 Rx"
+#define D_SENSOR_PN532_TX      "PN532 Tx"
+#define D_SENSOR_PN532_RX      "PN532 Rx"
 
 // Units
 #define D_UNIT_AMPERE "安"
diff --git a/sonoff/my_user_config.h b/sonoff/my_user_config.h
index f9aaf25d7..0d50b580b 100644
--- a/sonoff/my_user_config.h
+++ b/sonoff/my_user_config.h
@@ -375,6 +375,9 @@
 #define USE_ARMTRONIX_DIMMERS                    // Add support for Armtronix Dimmers (+1k4 code)
 #define USE_PS_16_DZ                             // Add support for PS-16-DZ Dimmer
 //#define USE_AZ7798                               // Add support for AZ-Instrument 7798 CO2 datalogger (+1k6 code)
+//#define USE_PN532_HSU                            // Add support for PN532 using HSU (Serial) interface (+3k7 code, 280 bytes mem)
+//  #define USE_PN532_DATA_FUNCTION                // Add sensor40 command support for erase, setting data block content (+1k7 code, 356 bytes mem)
+//  #define USE_PN532_DATA_RAW                     // Allow DATA block to be used by non-alpha-numberic data (-0k2 code, -32 bytes ram)
 
 // Power monitoring sensors -----------------------
 #define USE_PZEM004T                             // Add support for PZEM004T Energy monitor (+2k code)
diff --git a/sonoff/sonoff_template.h b/sonoff/sonoff_template.h
index 1e5e1a573..ff2ba6401 100644
--- a/sonoff/sonoff_template.h
+++ b/sonoff/sonoff_template.h
@@ -162,6 +162,8 @@ enum UserSelectablePins {
   GPIO_MCP39F5_TX,     // MCP39F501 Serial interface (Shelly2)
   GPIO_MCP39F5_RX,     // MCP39F501 Serial interface (Shelly2)
   GPIO_MCP39F5_RST,    // MCP39F501 Reset (Shelly2)
+  GPIO_PN532_RXD,      // PN532 NFC Serial Rx
+  GPIO_PN532_TXD,      // PN532 NFC Serial Tx
   GPIO_SENSOR_END };
 
 // Programmer selectable GPIO functionality offset by user selectable GPIOs
@@ -227,6 +229,7 @@ const char kSensorNames[] PROGMEM =
   D_SENSOR_BUTTON "1in|" D_SENSOR_BUTTON "2in|" D_SENSOR_BUTTON "3in|" D_SENSOR_BUTTON "4in|"
   D_SENSOR_NRG_SEL "|" D_SENSOR_NRG_SEL "i|" D_SENSOR_NRG_CF1 "|" D_SENSOR_HLW_CF "|" D_SENSOR_HJL_CF "|"
   D_SENSOR_MCP39F5_TX "|" D_SENSOR_MCP39F5_RX "|" D_SENSOR_MCP39F5_RST
+  D_SENSOR_PN532_TX "|" D_SENSOR_PN532_RX
   ;
 
 /********************************************************************************************/
@@ -546,6 +549,10 @@ const uint8_t kGpioNiceList[] PROGMEM = {
   GPIO_MAX31855CLK,    // MAX31855 Serial interface
   GPIO_MAX31855DO,     // MAX31855 Serial interface
 #endif
+#ifdef USE_PN532_HSU
+  GPIO_PN532_RXD,      // PN532 HSU Rx
+  GPIO_PN532_TXD,      // PN532 HSU Tx
+#endif
 };
 
 const uint8_t kModuleNiceList[MAXMODULE] PROGMEM = {
diff --git a/sonoff/xsns_40_pn532.ino b/sonoff/xsns_40_pn532.ino
index e69de29bb..af00720b2 100644
--- a/sonoff/xsns_40_pn532.ino
+++ b/sonoff/xsns_40_pn532.ino
@@ -0,0 +1,615 @@
+/*
+  xsns_40_pn532.ino - Support for PN532 (HSU) NFC Tag Reader
+
+  Copyright (C) 2019  Andre Thomas and Theo Arends
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifdef USE_PN532_HSU
+
+#define XSNS_40                                     40
+
+#include <TasmotaSerial.h>
+
+TasmotaSerial *PN532_Serial;
+
+#define PN532_INVALID_ACK                           -1
+#define PN532_TIMEOUT                               -2
+#define PN532_INVALID_FRAME                         -3
+#define PN532_NO_SPACE                              -4
+
+#define PN532_PREAMBLE                              0x00
+#define PN532_STARTCODE1                            0x00
+#define PN532_STARTCODE2                            0xFF
+#define PN532_POSTAMBLE                             0x00
+
+#define PN532_HOSTTOPN532                           0xD4
+#define PN532_PN532TOHOST                           0xD5
+
+#define PN532_ACK_WAIT_TIME                         0x0A
+
+#define PN532_COMMAND_GETFIRMWAREVERSION            0x02
+#define PN532_COMMAND_SAMCONFIGURATION              0x14
+#define PN532_COMMAND_RFCONFIGURATION               0x32
+#define PN532_COMMAND_INDATAEXCHANGE                0x40
+#define PN532_COMMAND_INLISTPASSIVETARGET           0x4A
+
+#define PN532_MIFARE_ISO14443A                      0x00
+#define MIFARE_CMD_READ                             0x30
+#define MIFARE_CMD_AUTH_A                           0x60
+#define MIFARE_CMD_AUTH_B                           0x61
+#define MIFARE_CMD_WRITE                            0xA0
+
+uint8_t pn532_model = 0;          // Used to maintain detection flag
+uint8_t pn532_command = 0;        // Used to carry command code between functions
+uint8_t pn532_scantimer = 0;      // Used to prevent multiple successful reads within 2 second window
+
+uint8_t pn532_packetbuffer[64];   // Global buffer used to store packet
+
+#ifdef USE_PN532_DATA_FUNCTION
+uint8_t pn532_function = 0;
+uint8_t pn532_newdata[16];
+uint8_t pn532_newdata_len = 0;
+#endif // USE_PN532_DATA_FUNCTION
+
+void PN532_Init(void)
+{
+  if ((pin[GPIO_PN532_RXD] < 99) && (pin[GPIO_PN532_TXD] < 99)) {
+    PN532_Serial = new TasmotaSerial(pin[GPIO_PN532_RXD], pin[GPIO_PN532_TXD], 1);
+    if (PN532_Serial->begin(115200)) {
+      if (PN532_Serial->hardwareSerial()) { ClaimSerial(); }
+      PN532_wakeup();
+      uint32_t ver = PN532_getFirmwareVersion();
+      if (ver) {
+        PN532_setPassiveActivationRetries(0xFF);
+        PN532_SAMConfig();
+        pn532_model = 1;
+        snprintf_P(log_data, sizeof(log_data),"NFC: PN532 NFC Reader detected (V%u.%u)",(ver>>16) & 0xFF, (ver>>8) & 0xFF);
+        AddLog(LOG_LEVEL_INFO);
+      }
+    }
+  }
+}
+
+int8_t PN532_receive(uint8_t *buf, int len, uint16_t timeout)
+{
+  int read_bytes = 0;
+  int ret;
+  unsigned long start_millis;
+  while (read_bytes < len) {
+    start_millis = millis();
+    do {
+      ret = PN532_Serial->read();
+      if (ret >= 0) {
+        break;
+      }
+    } while((timeout == 0) || ((millis()- start_millis ) < timeout));
+    
+    if (ret < 0) {
+      if (read_bytes) {
+        return read_bytes;
+      } else {
+        return PN532_TIMEOUT;
+      }
+    }
+    buf[read_bytes] = (uint8_t)ret;
+    read_bytes++;
+  }
+  return read_bytes;
+}
+
+int8_t PN532_readAckFrame(void)
+{
+  const uint8_t PN532_ACK[] = {0, 0, 0xFF, 0, 0xFF, 0};
+  uint8_t ackBuf[sizeof(PN532_ACK)];
+    
+  if (PN532_receive(ackBuf, sizeof(PN532_ACK), PN532_ACK_WAIT_TIME) <= 0) {
+    return PN532_TIMEOUT;
+  }
+
+  if (memcmp(&ackBuf, &PN532_ACK, sizeof(PN532_ACK))) {
+    return PN532_INVALID_ACK;
+  }
+  return 0;
+}
+
+int8_t PN532_writeCommand(const uint8_t *header, uint8_t hlen, const uint8_t *body = 0, uint8_t blen = 0)
+{
+  // Clear the serial buffer just in case
+  while(PN532_Serial->available()) { PN532_Serial->read(); }
+
+  pn532_command = header[0];
+  PN532_Serial->write((uint8_t)PN532_PREAMBLE);
+  PN532_Serial->write((uint8_t)PN532_STARTCODE1);
+  PN532_Serial->write(PN532_STARTCODE2);
+
+  uint8_t length = hlen + blen + 1;   // length of data field: TFI + DATA
+  PN532_Serial->write(length);
+  PN532_Serial->write(~length + 1);         // checksum of length
+
+  PN532_Serial->write(PN532_HOSTTOPN532);
+  uint8_t sum = PN532_HOSTTOPN532;    // sum of TFI + DATA
+
+  PN532_Serial->write(header, hlen);
+  for (uint8_t i = 0; i < hlen; i++) {
+    sum += header[i];
+  }
+
+  PN532_Serial->write(body, blen);
+  for (uint8_t i = 0; i < blen; i++) {
+    sum += body[i];
+  }
+
+  uint8_t checksum = ~sum + 1;            // checksum of TFI + DATA
+  PN532_Serial->write(checksum);
+  PN532_Serial->write((uint8_t)PN532_POSTAMBLE);
+  
+  return PN532_readAckFrame();
+}
+
+int16_t PN532_readResponse(uint8_t buf[], uint8_t len, uint16_t timeout = 50)
+{
+  uint8_t tmp[3];
+
+  // Read preamble and start code
+  if (PN532_receive(tmp, 3, timeout)<=0) {
+    return PN532_TIMEOUT;
+  }
+  if (0 != tmp[0] || 0!= tmp[1] || 0xFF != tmp[2]) {
+    return PN532_INVALID_FRAME;
+  }
+
+  // Get length of data to be received
+  uint8_t length[2];
+  if (PN532_receive(length, 2, timeout) <= 0) {
+    return PN532_TIMEOUT;
+  }
+  // Validate that frame is valid
+  if (0 != (uint8_t)(length[0] + length[1])) {
+    return PN532_INVALID_FRAME;
+  }
+  length[0] -= 2;
+  if (length[0] > len) {   // If this happens, then pn532_packetbuffer is not large enough
+    return PN532_NO_SPACE;
+  }
+
+  // Get the command byte
+  uint8_t cmd = pn532_command + 1;
+  if (PN532_receive(tmp, 2, timeout) <= 0) { // Time out while receiving
+    return PN532_TIMEOUT;
+  }
+  if (PN532_PN532TOHOST != tmp[0] || cmd != tmp[1]) { // Invalid frame received
+    return PN532_INVALID_FRAME;
+  }
+
+  if (PN532_receive(buf, length[0], timeout) != length[0]) { // Timed out
+    return PN532_TIMEOUT;
+  }
+  
+  uint8_t sum = PN532_PN532TOHOST + cmd;
+  for (uint8_t i=0; i<length[0]; i++) {
+    sum += buf[i];
+  }
+
+  // Checksum & postamble
+  if (PN532_receive(tmp, 2, timeout) <= 0) {
+    return PN532_TIMEOUT;
+  }
+  if (0 != (uint8_t)(sum + tmp[0]) || 0 != tmp[1]) { // Checksum fail, so frame must be invalid
+    return PN532_INVALID_FRAME;
+  }
+
+  return length[0];
+}
+
+uint32_t PN532_getFirmwareVersion(void)
+{
+  uint32_t response;
+
+  pn532_packetbuffer[0] = PN532_COMMAND_GETFIRMWAREVERSION;
+
+  if (PN532_writeCommand(pn532_packetbuffer, 1)) {
+    return 0;
+  }
+
+  // Read data packet
+  int16_t status = PN532_readResponse(pn532_packetbuffer, sizeof(pn532_packetbuffer));
+  if (0 > status) {
+    return 0;
+  }
+
+  response = pn532_packetbuffer[0];
+  response <<= 8;
+  response |= pn532_packetbuffer[1];
+  response <<= 8;
+  response |= pn532_packetbuffer[2];
+  response <<= 8;
+  response |= pn532_packetbuffer[3];
+
+  return response;
+}
+
+void PN532_wakeup(void)
+{
+  uint8_t wakeup[5] = {0x55, 0x55, 0, 0, 0 };
+  PN532_Serial->write(wakeup,sizeof(wakeup));
+
+  // Flush the serial buffer just in case there's garbage in there
+  while(PN532_Serial->available()) { PN532_Serial->read(); }
+}
+
+bool PN532_readPassiveTargetID(uint8_t cardbaudrate, uint8_t *uid, uint8_t *uidLength, uint16_t timeout = 50)
+{
+  pn532_packetbuffer[0] = PN532_COMMAND_INLISTPASSIVETARGET;
+  pn532_packetbuffer[1] = 1;  // max 1 cards at once (we can set this to 2 later)
+  pn532_packetbuffer[2] = cardbaudrate;
+  if (PN532_writeCommand(pn532_packetbuffer, 3)) {
+    return 0x0;  // command failed
+  }
+  // read data packet
+  if (PN532_readResponse(pn532_packetbuffer, sizeof(pn532_packetbuffer), timeout) < 0) {
+    return 0x0;
+  }
+
+  /* Check some basic stuff
+     b0              Tags Found
+     b1              Tag Number (only one used in this example)
+     b2..3           SENS_RES
+     b4              SEL_RES
+     b5              NFCID Length
+     b6..NFCIDLen    NFCID
+    */
+
+  if (pn532_packetbuffer[0] != 1) {
+    return 0;
+  }
+
+  uint16_t sens_res = pn532_packetbuffer[2];
+  sens_res <<= 8;
+  sens_res |= pn532_packetbuffer[3];
+
+  /* Card appears to be Mifare Classic */
+  *uidLength = pn532_packetbuffer[5];
+
+  for (uint8_t i = 0; i < pn532_packetbuffer[5]; i++) {
+    uid[i] = pn532_packetbuffer[6 + i];
+  }
+
+  return 1;
+}
+
+bool PN532_setPassiveActivationRetries(uint8_t maxRetries)
+{
+  pn532_packetbuffer[0] = PN532_COMMAND_RFCONFIGURATION;
+  pn532_packetbuffer[1] = 5;    // Config item 5 (MaxRetries)
+  pn532_packetbuffer[2] = 0xFF; // MxRtyATR (default = 0xFF)
+  pn532_packetbuffer[3] = 0x01; // MxRtyPSL (default = 0x01)
+  pn532_packetbuffer[4] = maxRetries;
+  if (PN532_writeCommand(pn532_packetbuffer, 5)) {
+    return 0; // no ACK
+  }
+  return (0 < PN532_readResponse(pn532_packetbuffer, sizeof(pn532_packetbuffer)));
+}
+
+bool PN532_SAMConfig(void)
+{
+  pn532_packetbuffer[0] = PN532_COMMAND_SAMCONFIGURATION;
+  pn532_packetbuffer[1] = 0x01; // normal mode
+  pn532_packetbuffer[2] = 0x14; // timeout 50ms * 20 = 1 second
+  pn532_packetbuffer[3] = 0x00; // we don't need the external IRQ pin
+  if (PN532_writeCommand(pn532_packetbuffer, 4)) {
+    return false;
+  }
+  return (0 < PN532_readResponse(pn532_packetbuffer, sizeof(pn532_packetbuffer)));
+}
+
+#ifdef USE_PN532_DATA_FUNCTION
+
+uint8_t mifareclassic_AuthenticateBlock (uint8_t *uid, uint8_t uidLen, uint32_t blockNumber, uint8_t keyNumber, uint8_t *keyData)
+{
+    uint8_t i;
+    uint8_t _key[6];
+    uint8_t _uid[7];
+    uint8_t _uidLen;
+
+    // Hang on to the key and uid data
+    memcpy(&_key, keyData, 6);
+    memcpy(&_uid, uid, uidLen);
+    _uidLen = uidLen;
+
+    // Prepare the authentication command //
+    pn532_packetbuffer[0] = PN532_COMMAND_INDATAEXCHANGE;   /* Data Exchange Header */
+    pn532_packetbuffer[1] = 1;                              /* Max card numbers */
+    pn532_packetbuffer[2] = (keyNumber) ? MIFARE_CMD_AUTH_B : MIFARE_CMD_AUTH_A;
+    pn532_packetbuffer[3] = blockNumber;                    /* Block Number (1K = 0..63, 4K = 0..255 */
+    memcpy(&pn532_packetbuffer[4], &_key, 6);
+    for (i = 0; i < _uidLen; i++) {
+        pn532_packetbuffer[10 + i] = _uid[i];              /* 4 bytes card ID */
+    }
+
+    if (PN532_writeCommand(pn532_packetbuffer, 10 + _uidLen)) { return 0; }
+
+    // Read the response packet
+    PN532_readResponse(pn532_packetbuffer, sizeof(pn532_packetbuffer));
+
+    // Check if the response is valid and we are authenticated???
+    // for an auth success it should be bytes 5-7: 0xD5 0x41 0x00
+    // Mifare auth error is technically byte 7: 0x14 but anything other and 0x00 is not good
+    if (pn532_packetbuffer[0] != 0x00) {
+        // Authentification failed
+        return 0;
+    }
+
+    return 1;
+}
+
+uint8_t mifareclassic_ReadDataBlock (uint8_t blockNumber, uint8_t *data)
+{
+    /* Prepare the command */
+    pn532_packetbuffer[0] = PN532_COMMAND_INDATAEXCHANGE;
+    pn532_packetbuffer[1] = 1;                      /* Card number */
+    pn532_packetbuffer[2] = MIFARE_CMD_READ;        /* Mifare Read command = 0x30 */
+    pn532_packetbuffer[3] = blockNumber;            /* Block Number (0..63 for 1K, 0..255 for 4K) */
+
+    /* Send the command */
+    if (PN532_writeCommand(pn532_packetbuffer, 4)) {
+        return 0;
+    }
+
+    /* Read the response packet */
+    PN532_readResponse(pn532_packetbuffer, sizeof(pn532_packetbuffer));
+
+    /* If byte 8 isn't 0x00 we probably have an error */
+    if (pn532_packetbuffer[0] != 0x00) {
+        return 0;
+    }
+
+    /* Copy the 16 data bytes to the output buffer        */
+    /* Block content starts at byte 9 of a valid response */
+    memcpy (data, &pn532_packetbuffer[1], 16);
+
+    return 1;
+}
+
+uint8_t mifareclassic_WriteDataBlock (uint8_t blockNumber, uint8_t *data)
+{
+    /* Prepare the first command */
+    pn532_packetbuffer[0] = PN532_COMMAND_INDATAEXCHANGE;
+    pn532_packetbuffer[1] = 1;                      /* Card number */
+    pn532_packetbuffer[2] = MIFARE_CMD_WRITE;       /* Mifare Write command = 0xA0 */
+    pn532_packetbuffer[3] = blockNumber;            /* Block Number (0..63 for 1K, 0..255 for 4K) */
+    memcpy(&pn532_packetbuffer[4], data, 16);       /* Data Payload */
+
+    /* Send the command */
+    if (PN532_writeCommand(pn532_packetbuffer, 20)) {
+        return 0;
+    }
+
+    /* Read the response packet */
+    return (0 < PN532_readResponse(pn532_packetbuffer, sizeof(pn532_packetbuffer)));
+}
+
+#endif // USE_PN532_DATA_FUNCTION
+
+void PN532_ScanForTag(void)
+{
+  if (!pn532_model) { return; }
+  uint8_t uid[] = { 0, 0, 0, 0, 0, 0, 0 };
+  uint8_t uid_len = 0;
+  uint8_t card_data[16];
+  bool erase_success = false;
+  bool set_success = false;
+  if (PN532_readPassiveTargetID(PN532_MIFARE_ISO14443A, uid, &uid_len)) {
+      char uids[15];
+      
+#ifdef USE_PN532_DATA_FUNCTION      
+      char card_datas[34];
+#endif // USE_PN532_DATA_FUNCTION      
+
+      sprintf(uids,"");
+      for (uint8_t i = 0;i < uid_len;i++) {
+        sprintf(uids,"%s%02X",uids,uid[i]);
+      }
+      
+#ifdef USE_PN532_DATA_FUNCTION      
+      if (uid_len == 4) { // Lets try to read block 1 of the mifare classic card for more information
+        uint8_t keyuniversal[6] = { 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF };
+        if (mifareclassic_AuthenticateBlock (uid, uid_len, 1, 1, keyuniversal)) {
+          if (mifareclassic_ReadDataBlock(1, card_data)) {
+#ifdef USE_PN532_DATA_RAW
+            memcpy(&card_datas,&card_data,sizeof(card_data));
+#else
+            for (uint8_t i = 0;i < sizeof(card_data);i++) {
+              if ((isalpha(card_data[i])) || ((isdigit(card_data[i])))) {
+                card_datas[i] = char(card_data[i]);
+              } else {
+                card_datas[i] = '\0';
+              }
+            }
+#endif // USE_PN532_DATA_RAW
+          }
+          if (pn532_function == 1) { // erase block 1 of card
+            for (uint8_t i = 0;i<16;i++) {
+              card_data[i] = 0x00;
+            }
+            if (mifareclassic_WriteDataBlock(1, card_data)) {
+              erase_success = true;
+              snprintf_P(log_data, sizeof(log_data),"NFC: PN532 NFC - Erase success");
+              AddLog(LOG_LEVEL_INFO);
+              memcpy(&card_datas,&card_data,sizeof(card_data)); // Cast block 1 to a string
+            }
+          }
+          if (pn532_function == 2) {
+#ifdef USE_PN532_DATA_RAW
+            memcpy(&card_data,&pn532_newdata,sizeof(card_data));
+            if (mifareclassic_WriteDataBlock(1, card_data)) {
+              set_success = true;
+              snprintf_P(log_data, sizeof(log_data),"NFC: PN532 NFC - Data write successful");
+              AddLog(LOG_LEVEL_INFO);
+              memcpy(&card_datas,&card_data,sizeof(card_data)); // Cast block 1 to a string
+            }
+#else
+            bool IsAlphaNumeric = true;
+            for (uint8_t i = 0;i < pn532_newdata_len;i++) {
+              if ((!isalpha(pn532_newdata[i])) && (!isdigit(pn532_newdata[i]))) {
+                IsAlphaNumeric = false;
+              }
+            }
+            if (IsAlphaNumeric) {
+              memcpy(&card_data,&pn532_newdata,pn532_newdata_len);
+              card_data[pn532_newdata_len] = '\0'; // Enforce null termination
+              if (mifareclassic_WriteDataBlock(1, card_data)) {
+                set_success = true;
+                snprintf_P(log_data, sizeof(log_data),"NFC: PN532 NFC - Data write successful");
+                AddLog(LOG_LEVEL_INFO);
+                memcpy(&card_datas,&card_data,sizeof(card_data)); // Cast block 1 to a string
+              }
+            } else {
+              snprintf_P(log_data, sizeof(log_data),"NFC: PN532 NFC - Data must be alphanumeric");
+              AddLog(LOG_LEVEL_INFO);
+            }
+#endif // USE_PN532_DATA_RAW
+          }
+        } else {
+          sprintf(card_datas,"AUTHFAIL");
+        }
+      }
+      switch (pn532_function) {
+        case 0x01:
+          if (!erase_success) {
+            snprintf_P(log_data, sizeof(log_data),"NFC: PN532 NFC - Erase fail - exiting erase mode");
+            AddLog(LOG_LEVEL_INFO);
+          }
+          break;
+        case 0x02:
+          if (!set_success) {
+            snprintf_P(log_data, sizeof(log_data),"NFC: PN532 NFC - Write failed - exiting set mode");
+            AddLog(LOG_LEVEL_INFO);
+          }
+        default:
+          break;
+      }
+      pn532_function = 0;
+#endif // USE_PN532_DATA_FUNCTION      
+      
+      snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("{\"" D_JSON_TIME "\":\"%s\""), GetDateAndTime(DT_LOCAL).c_str());
+
+#ifdef USE_PN532_DATA_FUNCTION
+      snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s,\"PN532\":{\"UID\":\"%s\", \"DATA\":\"%s\"}}"), mqtt_data, uids, card_datas);
+#else
+      snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s,\"PN532\":{\"UID\":\"%s\"}}"), mqtt_data, uids);
+#endif // USE_PN532_DATA_FUNCTION      
+
+      MqttPublishPrefixTopic_P(TELE, PSTR(D_RSLT_SENSOR), Settings.flag.mqtt_sensor_retain);
+
+#ifdef USE_PN532_CAUSE_EVENTS
+
+      char command[71];
+#ifdef USE_PN532_DATA_FUNCTION
+      sprintf(command,"backlog event PN532_UID=%s;event PN532_DATA=%s",uids,card_datas);
+#else
+      sprintf(command,"event PN532_UID=%s",uids);
+#endif // USE_PN532_DATA_FUNCTION      
+      ExecuteCommand(command, SRC_RULE);
+#endif // USE_PN532_CAUSE_EVENTS
+      
+      pn532_scantimer = 7; // Ignore tags found for two seconds
+  }
+}
+
+#ifdef USE_PN532_DATA_FUNCTION
+
+bool PN532_Command(void)
+{
+  bool serviced = true;
+  uint8_t paramcount = 0;
+  if (XdrvMailbox.data_len > 0) {
+    paramcount=1;
+  } else {
+    serviced = false;
+    return serviced;
+  }
+  char sub_string[XdrvMailbox.data_len];
+  char sub_string_tmp[XdrvMailbox.data_len];
+  for (uint8_t ca=0;ca<XdrvMailbox.data_len;ca++) {
+    if ((' ' == XdrvMailbox.data[ca]) || ('=' == XdrvMailbox.data[ca])) { XdrvMailbox.data[ca] = ','; }
+    if (',' == XdrvMailbox.data[ca]) { paramcount++; }
+  }
+  UpperCase(XdrvMailbox.data,XdrvMailbox.data);
+  if (!strcmp(subStr(sub_string, XdrvMailbox.data, ",", 1),"E")) {
+    pn532_function = 1; // Block 1 of next card/tag will be reset to 0x00...
+    snprintf_P(log_data, sizeof(log_data),"NFC: PN532 NFC - Next scanned tag data block 1 will be erased");
+    AddLog(LOG_LEVEL_INFO);
+    snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("{\"" D_JSON_TIME "\":\"%s\""), GetDateAndTime(DT_LOCAL).c_str());
+    snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s,\"PN532\":{\"COMMAND\":\"E\"\"}}"), mqtt_data);
+    return serviced;
+  }
+  if (!strcmp(subStr(sub_string, XdrvMailbox.data, ",", 1),"S")) {
+    if (paramcount > 1) {
+      if (XdrvMailbox.data[XdrvMailbox.data_len-1] == ',') {
+        serviced = false;
+        return serviced;
+      }
+      sprintf(sub_string_tmp,subStr(sub_string, XdrvMailbox.data, ",", 2));
+      pn532_newdata_len = strlen(sub_string_tmp);
+      if (pn532_newdata_len > 15) { pn532_newdata_len = 15; }
+      memcpy(&pn532_newdata,&sub_string_tmp,pn532_newdata_len);
+      pn532_newdata[pn532_newdata_len] = 0x00; // Null terminate the string
+      pn532_function = 2;
+      snprintf_P(log_data, sizeof(log_data),"NFC: PN532 NFC - Next scanned tag data block 1 will be set to '%s'",pn532_newdata);
+      AddLog(LOG_LEVEL_INFO);
+      snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("{\"" D_JSON_TIME "\":\"%s\""), GetDateAndTime(DT_LOCAL).c_str());
+      snprintf_P(mqtt_data, sizeof(mqtt_data), PSTR("%s,\"PN532\":{\"COMMAND\":\"S\"\"}}"), mqtt_data);
+      return serviced;
+    }
+  }
+}
+
+#endif // USE_PN532_DATA_FUNCTION
+
+bool Xsns40(uint8_t function)
+{
+  bool result = false;
+  
+  switch (function) {
+    case FUNC_INIT:
+      PN532_Init();
+      result = true;
+      break;
+    case FUNC_EVERY_50_MSECOND:
+      break;
+    case FUNC_EVERY_100_MSECOND:
+      break;
+    case FUNC_EVERY_250_MSECOND:
+      if (pn532_scantimer > 0) {
+        pn532_scantimer--;
+      } else {
+        PN532_ScanForTag();
+      }
+      break;
+    case FUNC_EVERY_SECOND:
+      break;
+#ifdef USE_PN532_DATA_FUNCTION      
+    case FUNC_COMMAND:
+      if (XSNS_40 == XdrvMailbox.index) {
+        result = PN532_Command();
+      }
+      break;
+#endif      
+  }
+  return result;
+}
+
+#endif // USE_PN532_HSU