diff --git a/README.md b/README.md
index 00efc562..3010e460 100644
--- a/README.md
+++ b/README.md
@@ -20,18 +20,23 @@ This can all be done with a single small and cheap ESP32 board for less than $20
 # Hardware
 
 Supported ESP32 based LoRa IoT boards:
-- Heltec LoRa-32 {1}
-- TTGOv1 {1}
-- TTGOv2 {1}{4}
-- TTGOv2.1 {1}{5}
-- TTGO T-Beam {4}{5}
-- Pycom LoPy {2}
-- Pycom LoPy4 {2}
-- Pycom FiPy {2}
-- LoLin32 with [LoraNode32 shield](https://github.com/hallard/LoLin32-Lora) {2}{3}
-- LoLin32 Lite with [LoraNode32-Lite shield](https://github.com/hallard/LoLin32-Lite-Lora) {2}{3}
+- **Heltec LoRa-32**  a)
+- **TTGOv1**  a)
+- **TTGOv2**  a,d)
+- **TTGOv2.1**  a),e)
+- **TTGO T-Beam**  d),e),f)
+- **Pycom LoPy**  b),f)*
+- **Pycom LoPy4**  b),f)*
+- **Pycom FiPy**  b),f)*
+- **LoLin32** with [LoraNode32 shield](https://github.com/hallard/LoLin32-Lora)  b),c)
+- **LoLin32 Lite** with [LoraNode32-Lite shield](https://github.com/hallard/LoLin32-Lite-Lora)  b),c)
 
-{1} on board OLED Display supported; {2} on board RGB LED supported; {3} on board Hardware unique DEVEUI supported; {4} special wiring needed, see instructions in file /hal/<board>.h; {5} battery voltage monitoring supported
+a) on board OLED Display supported;
+b) on board RGB LED supported;
+c) on board Hardware unique DEVEUI supported;
+d) external wiring needed, see instructions in file /hal/<board>.h;
+e) battery voltage monitoring supported;
+f) on board GPS supported, *for Pycom devices with additional PyTrack board
 
 Target platform must be selected in [platformio.ini](https://github.com/cyberman54/ESP32-Paxcounter/blob/master/platformio.ini).<br>
 Hardware dependent settings (pinout etc.) are stored in board files in /hal directory.<br>
@@ -102,40 +107,68 @@ Legend for RGB LED (LoPy/LoPy4/FiPy/Lolin32 only):
 
 # Payload
 
-FPort1:
+**LoRaWAN Port #1:**
 
-	byte 1:			16-bit WiFi counter, MSB
-	byte 2:			16-bit WiFi counter, LSB
-	byte 3:			16-bit BLE counter, MSB
-	byte 4:			16-bit BLE counter, LSB
+	Paxcounter data
 
-FPort2:
+	byte 1-2:	Number of unique pax, first seen on Wifi
+	byte 3-4:	Number of unique pax, first seen on Bluetooth [0 if BT disabled]
+	
+	GPS data (only, if GPS is present and has a fix)
+	
+	bytes 5-8:	GPS latitude
+	bytes 9-12:	GPS longitude
+	bytes 13-14:	GPS number of satellites
+	bytes 15-16:	GPS HDOP
+	bytes 17-18:	GPS altitude [meter]
 
-	see remote command set
+**LoRaWAN Port #2:**
 
-If you're using [TheThingsNetwork](https://www.thethingsnetwork.org/) you may want to use a payload converter. Go to TTN Console - Application - Payload Formats and paste the code example below in tabs Decoder and Converter. Make sure that your application parses the fields `pax`, `ble` and `wifi`.
+	- see remote control -
 
-Decoder:
+If you're using [TheThingsNetwork](https://www.thethingsnetwork.org/) (TTN) you may want to use a payload converter. Go to TTN Console - Application - Payload Formats and paste the code example below in tabs Decoder and Converter. Make sure that your application parses the fields `pax`, `ble` and `wifi`.
+
+To map a GPS capable paxcounter device and at the same time contribute to TTN coverage mapping, you simply activate the [TTNmapper integration](https://www.thethingsnetwork.org/docs/applications/ttnmapper/) in TTN Console. Paxcounter generates ttnmapper compatible data fields.
+
+**Decoder:**
 
 ```javascript
 function Decoder(bytes, port) {
-    var decoded = {};
-    if (port === 1) {
-      decoded.wifi = (bytes[0] << 8) | bytes[1];
-      decoded.ble = (bytes[2] << 8) | bytes[3];
+  var decoded = {};
+
+  if (port === 1) {
+    var i = 0;
+    decoded.wifi = (bytes[i++] << 8) | bytes[i++];
+    decoded.ble =  (bytes[i++] << 8) | bytes[i++];
+    if (bytes.length > 4) {
+      decoded.latitude =  ( (bytes[i++]) | (bytes[i++] << 8) | (bytes[i++] << 16) | bytes[i++] << 24 );
+      decoded.longitude = ( (bytes[i++]) | (bytes[i++] << 8) | (bytes[i++] << 16) | bytes[i++] << 24 );
+      decoded.sats = 	  (  bytes[i++]  | (bytes[i++] << 8) );
+      decoded.hdop = 	  (  bytes[i++]  | (bytes[i++] << 8) );
+      decoded.altitude =  (  bytes[i++]  | (bytes[i++] << 8) );
     }
-    return decoded;
+  }
+
+  return decoded;
 }
 ```
 
-Converter:
+**Converter:**
 
 ```javascript
 function Converter(decoded, port) {
+  
   var converted = decoded;
+
   if (port === 1) {
     converted.pax = converted.ble + converted.wifi;
+    if (converted.hdop) {
+      converted.hdop /= 100;
+      converted.latitude /= 1000000;
+      converted.longitude /= 1000000;
+    }
   }
+
   return converted;
 }
 ```
@@ -262,6 +295,14 @@ device answers with it's current configuration. The configuration is a C structu
 
 	bytes 1-2:		battery voltage in millivolt, 0 if unreadable (little endian format)
 
+0x84 get device GPS status
+
+	bytes 1-4:		latitude
+	bytes 5-8:		longitude
+	byte 9-10:		number of satellites
+	byte 11-12:		HDOP
+	bytes 13-14:		altidute [meter]
+
 # License
 
 Copyright  2018 Oliver Brandmueller <ob@sysadm.in>
diff --git a/platformio.ini b/platformio.ini
index 3fb30f06..be9dda45 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -11,11 +11,11 @@
 
 ; ---> SELECT TARGET PLATFORM HERE! <---
 [platformio]
-;env_default = heltec
+env_default = heltec
 ;env_default = ttgov1
 ;env_default = ttgov2
 ;env_default = ttgov21
-env_default = ttgobeam
+;env_default = ttgobeam
 ;env_default = lopy
 ;env_default = lopy4
 ;env_default = fipy
@@ -27,11 +27,12 @@ description = Paxcounter is a proof-of-concept ESP32 device for metering passeng
 [common_env_data]
 platform_espressif32 = espressif32@>=1.0.2
 board_build.partitions = no_ota.csv
-board_upload.maximum_size = 2097152
 lib_deps_display =
     U8g2@>=2.22.14
 lib_deps_rgbled =
-    SmartLeds
+    SmartLeds@>=1.1.3
+lib_deps_gps =
+    TinyGPSPlus@>=1.0.2
 build_flags = 
 ; we need build_flag for logging, otherwise we can't use ESP_LOGx in arduino framework
 ; ---> NOTE: For production run set DEBUG_LEVEL level to NONE! <---
@@ -51,7 +52,6 @@ platform = ${common_env_data.platform_espressif32}
 framework = arduino
 board = heltec_wifi_lora_32
 board_build.partitions = ${common_env_data.board_build.partitions}
-board_upload.maximum_size = ${common_env_data.board_upload.maximum_size}
 monitor_speed = 115200
 upload_speed = 115200 
 lib_deps = 
@@ -65,7 +65,6 @@ platform = ${common_env_data.platform_espressif32}
 framework = arduino
 board = esp32dev
 board_build.partitions = ${common_env_data.board_build.partitions}
-board_upload.maximum_size = ${common_env_data.board_upload.maximum_size}
 monitor_speed = 115200
 upload_speed = 115200 
 lib_deps = 
@@ -79,7 +78,6 @@ platform = ${common_env_data.platform_espressif32}
 framework = arduino
 board = esp32dev
 board_build.partitions = ${common_env_data.board_build.partitions}
-board_upload.maximum_size = ${common_env_data.board_upload.maximum_size}
 monitor_speed = 115200
 upload_speed = 921600
 lib_deps = 
@@ -93,7 +91,6 @@ platform = ${common_env_data.platform_espressif32}
 framework = arduino
 board = esp32dev
 board_build.partitions = ${common_env_data.board_build.partitions}
-board_upload.maximum_size = ${common_env_data.board_upload.maximum_size}
 monitor_speed = 115200
 upload_speed = 921600
 lib_deps = 
@@ -107,11 +104,11 @@ platform = ${common_env_data.platform_espressif32}
 framework = arduino
 board = esp32dev
 board_build.partitions = ${common_env_data.board_build.partitions}
-board_upload.maximum_size = ${common_env_data.board_upload.maximum_size}
 monitor_speed = 115200
 upload_speed = 921600
 lib_deps = 
     ${common_env_data.lib_deps_display}
+    ${common_env_data.lib_deps_gps}
 build_flags = 
     ${common_env_data.build_flags}
     -include "src/hal/ttgobeam.h"
@@ -121,7 +118,6 @@ platform = espressif32@1.0.1
 framework = arduino
 board = esp32dev
 board_build.partitions = ${common_env_data.board_build.partitions}
-board_upload.maximum_size = ${common_env_data.board_upload.maximum_size}
 monitor_speed = 115200
 upload_speed = 921600
 lib_deps = 
@@ -135,7 +131,6 @@ platform = ${common_env_data.platform_espressif32}
 framework = arduino
 board = esp32dev
 board_build.partitions = ${common_env_data.board_build.partitions}
-board_upload.maximum_size = ${common_env_data.board_upload.maximum_size}
 monitor_speed = 115200
 upload_speed = 921600
 lib_deps = 
@@ -149,7 +144,6 @@ platform = ${common_env_data.platform_espressif32}
 framework = arduino
 board = esp32dev
 board_build.partitions = ${common_env_data.board_build.partitions}
-board_upload.maximum_size = ${common_env_data.board_upload.maximum_size}
 monitor_speed = 115200
 upload_speed = 921600
 lib_deps =
@@ -163,7 +157,6 @@ platform = ${common_env_data.platform_espressif32}
 framework = arduino
 board = lolin32
 board_build.partitions = ${common_env_data.board_build.partitions}
-board_upload.maximum_size = ${common_env_data.board_upload.maximum_size}
 monitor_speed = 115200
 upload_speed = 256000
 lib_deps = 
@@ -177,7 +170,6 @@ platform = ${common_env_data.platform_espressif32}
 framework = arduino 
 board = lolin32
 board_build.partitions = ${common_env_data.board_build.partitions}
-board_upload.maximum_size = ${common_env_data.board_upload.maximum_size}
 monitor_speed = 115200
 upload_speed = 921600
 lib_deps = 
diff --git a/src/configmanager.cpp b/src/configmanager.cpp
index 97ae1ee5..867a071f 100644
--- a/src/configmanager.cpp
+++ b/src/configmanager.cpp
@@ -22,7 +22,7 @@ void defaultConfig() {
     cfg.txpower       = 15;             // 2-15, lora tx power
     cfg.adrmode       = 1;              // 0=disabled, 1=enabled
     cfg.screensaver   = 0;              // 0=disabled, 1=enabled
-    cfg.screenon      = 1;              // 0=disbaled, 1=enabled
+    cfg.screenon      = 1;              // 0=disabled, 1=enabled
     cfg.countermode   = 0;              // 0=cyclic, 1=cumulative, 2=cyclic confirmed
     cfg.rssilimit     = 0;              // threshold for rssilimiter, negative value!
     cfg.sendcycle     = SEND_SECS;      // payload send cycle [seconds/2]
@@ -32,6 +32,7 @@ void defaultConfig() {
     cfg.wifiant       = 0;              // 0=internal, 1=external (for LoPy/LoPy4)
     cfg.vendorfilter  = 1;              // 0=disabled, 1=enabled
     cfg.rgblum        = RGBLUMINOSITY;  // RGB Led luminosity (0..100%)
+    cfg.gpsmode       = 1;              // 0=disabled, 1=enabled
 
     strncpy( cfg.version, PROGVERSION, sizeof(cfg.version)-1 );
 }
@@ -120,6 +121,9 @@ void saveConfig() {
       if( nvs_get_i8(my_handle, "rgblum", &flash8) != ESP_OK || flash8 != cfg.rgblum )
           nvs_set_i8(my_handle, "rgblum", cfg.rgblum);
 
+      if( nvs_get_i8(my_handle, "gpsmode", &flash8) != ESP_OK || flash8 != cfg.gpsmode )
+      nvs_set_i8(my_handle, "gpsmode", cfg.gpsmode);
+
       if( nvs_get_i16(my_handle, "rssilimit", &flash16) != ESP_OK || flash16 != cfg.rssilimit )
         nvs_set_i16(my_handle, "rssilimit", cfg.rssilimit);
 
@@ -284,6 +288,14 @@ void loadConfig() {
       saveConfig();
     }
 
+    if( nvs_get_i8(my_handle, "gpsmode", &flash8) == ESP_OK ) {
+      cfg.gpsmode = flash8;
+      ESP_LOGI(TAG, "GPSmode = %d", flash8);
+    } else {
+      ESP_LOGI(TAG, "GPSmode set to default %d", cfg.gpsmode);
+      saveConfig();
+    }
+
     nvs_close(my_handle);
     ESP_LOGI(TAG, "Done");
 
diff --git a/src/configmanager.h b/src/configmanager.h
new file mode 100644
index 00000000..f9c5d3fa
--- /dev/null
+++ b/src/configmanager.h
@@ -0,0 +1,8 @@
+#ifndef CONFIGMANAGER_H
+#define CONFIGMANAGER_H
+
+void eraseConfig(void);
+void saveConfig(void);
+void loadConfig(void);
+
+#endif
\ No newline at end of file
diff --git a/src/globals.h b/src/globals.h
index 275f1c3b..04ef15d7 100644
--- a/src/globals.h
+++ b/src/globals.h
@@ -11,6 +11,11 @@
     #include <U8x8lib.h>
 #endif
 
+//GPS
+#ifdef HAS_GPS
+    #include <TinyGPS++.h>
+#endif
+
 // LMIC-Arduino LoRaWAN Stack
 #include <lmic.h>
 #include <hal/hal.h>
@@ -32,7 +37,7 @@ typedef struct {
   uint8_t screensaver;                  // 0=disabled, 1=enabled
   uint8_t screenon;                     // 0=disabled, 1=enabled
   uint8_t countermode;                  // 0=cyclic unconfirmed, 1=cumulative, 2=cyclic confirmed
-  int16_t rssilimit;                   // threshold for rssilimiter, negative value!
+  int16_t rssilimit;                    // threshold for rssilimiter, negative value!
   uint8_t sendcycle;                    // payload send cycle [seconds/2]
   uint8_t wifichancycle;                // wifi channel switch cycle [seconds/100]
   uint8_t blescantime;                  // BLE scan cycle duration [seconds]
@@ -40,14 +45,29 @@ typedef struct {
   uint8_t wifiant;                      // 0=internal, 1=external (for LoPy/LoPy4)
   uint8_t vendorfilter;                 // 0=disabled, 1=enabled
   uint8_t rgblum;                       // RGB Led luminosity (0..100%)
-  char version[10];                    // Firmware version
+  uint8_t gpsmode;                      // 0=disabled, 1=enabled
+  char version[10];                     // Firmware version
   } configData_t;
 
+#ifdef HAS_GPS
+  typedef struct {
+    uint32_t latitude;
+    uint32_t longitude;
+    uint8_t satellites;
+    uint16_t hdop;
+    uint16_t altitude;
+    } gpsStatus_t;
+  extern gpsStatus_t gps_status;        // struct for storing gps data
+  extern TinyGPSPlus gps;               // Make TinyGPS++ instance globally availabe
+#endif
+
 extern configData_t cfg;
 extern uint64_t uptimecounter;
-extern osjob_t sendjob;
+extern osjob_t sendjob, rcmdjob;
 extern char display_lora[], display_lmic[];
 extern int countermode, screensaver, adrmode, lorasf, txpower, rlim;
 extern uint16_t macs_total, macs_wifi, macs_ble; // MAC counters
 extern std::set<uint16_t> macs;
-extern hw_timer_t * channelSwitch;      // hardware timer used for wifi channel switching
\ No newline at end of file
+extern hw_timer_t * channelSwitch; // hardware timer used for wifi channel switching
+extern xref2u1_t rcmd_data;        // buffer for rcommand results size
+extern u1_t rcmd_data_size;        // buffer for rcommand results size
diff --git a/src/gpsread.cpp b/src/gpsread.cpp
new file mode 100644
index 00000000..eb38eb73
--- /dev/null
+++ b/src/gpsread.cpp
@@ -0,0 +1,80 @@
+#ifdef HAS_GPS
+
+#include "globals.h"
+
+// Local logging tag
+static const char TAG[] = "main";
+
+// read GPS data and cast to global struct
+void gps_read() {
+    gps_status.latitude     =   (uint32_t) (gps.location.lat() * 1000000);
+    gps_status.longitude    =   (uint32_t) (gps.location.lng() * 1000000);
+    gps_status.satellites   =   (uint8_t) gps.satellites.value();
+    gps_status.hdop         =   (uint16_t) gps.hdop.value();
+    gps_status.altitude     =   (uint16_t) gps.altitude.meters(); 
+}
+
+// GPS serial feed FreeRTos Task
+void gps_loop(void * pvParameters) {
+
+    configASSERT( ( ( uint32_t ) pvParameters ) == 1 ); // FreeRTOS check
+
+    // initialize and, if needed, configure, GPS
+    #if defined GPS_SERIAL
+        HardwareSerial GPS_Serial(1);  
+    #elif defined GPS_I2C
+        // to be done
+    #endif
+
+    while(1) {
+
+        if (cfg.gpsmode)
+        {
+            #if defined GPS_SERIAL
+                
+                // serial connect to GPS device
+                GPS_Serial.begin(GPS_SERIAL);
+                
+                while(cfg.gpsmode) {
+                    // feed GPS decoder with serial NMEA data from GPS device
+                    while (GPS_Serial.available()) {
+                        gps.encode(GPS_Serial.read());
+                    }
+                    vTaskDelay(1/portTICK_PERIOD_MS); // reset watchdog
+                }    
+                // after GPS function was disabled, close connect to GPS device
+                GPS_Serial.end();
+
+            #elif defined GPS_I2C
+                
+                // I2C connect to GPS device with 100 kHz
+                Wire.begin(GPS_I2C_PINS, 100000);
+                Wire.beginTransmission(GPS_I2C_ADDRESS_WRITE);
+                Wire.write(0x00); 
+
+                i2c_ret == Wire.beginTransmission(GPS_I2C_ADDRESS_READ);
+                if (i2c_ret == 0) { // check if device seen on i2c bus
+                    while(cfg.gpsmode) {
+                                // feed GPS decoder with serial NMEA data from GPS device
+                                while (Wire.available()) {
+                                    Wire.requestFrom(GPS_I2C_ADDRESS_READ, 255);
+                                    gps.encode(Wire.read());
+                                    vTaskDelay(1/portTICK_PERIOD_MS); // reset watchdog
+                                }
+                            }    
+                    // after GPS function was disabled, close connect to GPS device
+
+                    Wire.endTransmission();
+                    Wire.setClock(400000); // Set back to 400KHz to speed up OLED
+                }
+
+            #endif
+        }
+       
+        vTaskDelay(1/portTICK_PERIOD_MS); // reset watchdog
+
+    } // end of infinite loop
+
+} // gps_loop()
+    
+#endif // HAS_GPS
\ No newline at end of file
diff --git a/src/hal/fipy.h b/src/hal/fipy.h
index 7622d811..9f88928d 100644
--- a/src/hal/fipy.h
+++ b/src/hal/fipy.h
@@ -2,18 +2,18 @@
 
 #define CFG_sx1272_radio 1
 #define HAS_LED NOT_A_PIN // FiPy has no on board LED, so we use RGB LED
-#define HAS_RGB_LED   0  // WS2812B RGB LED on GPIO0
+#define HAS_RGB_LED   GPIO_NUM_0  // WS2812B RGB LED on GPIO0
 
 // Hardware pin definitions for Pycom FiPy board
-#define PIN_SPI_SS    18
-#define PIN_SPI_MOSI  27
-#define PIN_SPI_MISO  19
-#define PIN_SPI_SCK   5
+#define PIN_SPI_SS    GPIO_NUM_18
+#define PIN_SPI_MOSI  GPIO_NUM_27
+#define PIN_SPI_MISO  GPIO_NUM_19
+#define PIN_SPI_SCK   GPIO_NUM_5
 #define RST   LMIC_UNUSED_PIN
-#define DIO0  23 // LoRa IRQ
-#define DIO1  23 // workaround
+#define DIO0  GPIO_NUM_23 // LoRa IRQ
+#define DIO1  GPIO_NUM_23 // workaround
 #define DIO2  LMIC_UNUSED_PIN
 
 // select WIFI antenna (internal = onboard / external = u.fl socket)
-#define HAS_ANTENNA_SWITCH  21      // pin for switching wifi antenna
-#define WIFI_ANTENNA 0              // 0 = internal, 1 = external
+#define HAS_ANTENNA_SWITCH  GPIO_NUM_21 // pin for switching wifi antenna
+#define WIFI_ANTENNA 0  // 0 = internal, 1 = external
diff --git a/src/hal/heltec.h b/src/hal/heltec.h
index ed2e63db..74bdb89a 100644
--- a/src/hal/heltec.h
+++ b/src/hal/heltec.h
@@ -8,18 +8,18 @@
 #define HAS_BUTTON GPIO_NUM_0 // button "PROG" on board
 
 // re-define pin definitions of pins_arduino.h
-#define PIN_SPI_SS    18 // ESP32 GPIO18 (Pin18) -- SX1276 NSS (Pin19) SPI Chip Select Input
-#define PIN_SPI_MOSI  27 // ESP32 GPIO27 (Pin27) -- SX1276 MOSI (Pin18) SPI Data Input
-#define PIN_SPI_MISO  19 // ESP32 GPIO19 (Pin19) -- SX1276 MISO (Pin17) SPI Data Output
-#define PIN_SPI_SCK   5  // ESP32 GPIO5 (Pin5)   -- SX1276 SCK (Pin16) SPI Clock Input
+#define PIN_SPI_SS    GPIO_NUM_18 // ESP32 GPIO18 (Pin18) -- SX1276 NSS (Pin19) SPI Chip Select Input
+#define PIN_SPI_MOSI  GPIO_NUM_27 // ESP32 GPIO27 (Pin27) -- SX1276 MOSI (Pin18) SPI Data Input
+#define PIN_SPI_MISO  GPIO_NUM_19 // ESP32 GPIO19 (Pin19) -- SX1276 MISO (Pin17) SPI Data Output
+#define PIN_SPI_SCK   GPIO_NUM_5  // ESP32 GPIO5 (Pin5)   -- SX1276 SCK (Pin16) SPI Clock Input
 
 // non arduino pin definitions
-#define RST   14 // ESP32 GPIO14 (Pin14) -- SX1276 NRESET (Pin7) Reset Trigger Input
-#define DIO0  26 // ESP32 GPIO26 (Pin15) -- SX1276 DIO0 (Pin8) used by LMIC for detecting LoRa RX_Done & TX_Done
-#define DIO1  33 // ESP32 GPIO33 (Pin13) -- SX1276 DIO1 (Pin9) used by LMIC for detecting LoRa RX_Timeout
+#define RST   GPIO_NUM_14 // ESP32 GPIO14 (Pin14) -- SX1276 NRESET (Pin7) Reset Trigger Input
+#define DIO0  GPIO_NUM_26 // ESP32 GPIO26 (Pin15) -- SX1276 DIO0 (Pin8) used by LMIC for detecting LoRa RX_Done & TX_Done
+#define DIO1  GPIO_NUM_33 // ESP32 GPIO33 (Pin13) -- SX1276 DIO1 (Pin9) used by LMIC for detecting LoRa RX_Timeout
 #define DIO2  LMIC_UNUSED_PIN // 32 ESP32 GPIO32 (Pin12) -- SX1276 DIO2 (Pin10) not used by LMIC for LoRa (Timeout for FSK only)
 
 // Hardware pin definitions for Heltec LoRa-32 Board with OLED SSD1306 I2C Display
-#define OLED_RST 16 // ESP32 GPIO16 (Pin16) -- SD1306 RST
-#define OLED_SDA 4  // ESP32 GPIO4 (Pin4)   -- SD1306 D1+D2
-#define OLED_SCL 15 // ESP32 GPIO15 (Pin15) -- SD1306 D0
+#define OLED_RST GPIO_NUM_16 // ESP32 GPIO16 (Pin16) -- SD1306 RST
+#define OLED_SDA GPIO_NUM_4  // ESP32 GPIO4 (Pin4)   -- SD1306 D1+D2
+#define OLED_SCL GPIO_NUM_15 // ESP32 GPIO15 (Pin15) -- SD1306 D0
diff --git a/src/hal/lopy.h b/src/hal/lopy.h
index 219a3a96..d54004f6 100644
--- a/src/hal/lopy.h
+++ b/src/hal/lopy.h
@@ -2,16 +2,25 @@
 
 #define CFG_sx1272_radio 1
 #define HAS_LED NOT_A_PIN // LoPy4 has no on board LED, so we use RGB LED on LoPy4
-#define HAS_RGB_LED   0  // WS2812B RGB LED on GPIO0
+#define HAS_RGB_LED GPIO_NUM_0  // WS2812B RGB LED on GPIO0
+
+// !!EXPERIMENTAL - not tested yet!!
+// uncomment this only if your LoPy lives on a Pytrack expansion board with GPS
+// see http://www.quectel.com/UploadImage/Downlad/Quectel_L76-L_I2C_Application_Note_V1.0.pdf
+//#define HAS_GPS 1
+//#define GPS_I2C_PINS GPIO_NUM_9, GPIO_NUM_8 // SDA, SCL
+//#define GPS_I2C_ADDRESS_READ 0x21
+//#define GPS_I2C_ADDRESS_WRITE 0x20
+//#define HAS_BUTTON GPIO_NUM_4
 
 // Hardware pin definitions for Pycom LoPy board
-#define PIN_SPI_SS    17
-#define PIN_SPI_MOSI  27
-#define PIN_SPI_MISO  19
-#define PIN_SPI_SCK   5
-#define RST   18
-#define DIO0  23 // LoRa IRQ
-#define DIO1  23 // workaround
+#define PIN_SPI_SS    GPIO_NUM_17
+#define PIN_SPI_MOSI  GPIO_NUM_27
+#define PIN_SPI_MISO  GPIO_NUM_19
+#define PIN_SPI_SCK   GPIO_NUM_5
+#define RST   GPIO_NUM_18
+#define DIO0  GPIO_NUM_23 // LoRa IRQ
+#define DIO1  GPIO_NUM_23 // workaround
 #define DIO2  LMIC_UNUSED_PIN
 
 // select WIFI antenna (internal = onboard / external = u.fl socket)
diff --git a/src/hal/lopy4.h b/src/hal/lopy4.h
index aaed263a..708a861d 100644
--- a/src/hal/lopy4.h
+++ b/src/hal/lopy4.h
@@ -2,16 +2,25 @@
 
 #define CFG_sx1276_radio 1
 #define HAS_LED NOT_A_PIN // LoPy4 has no on board LED, so we use RGB LED on LoPy4
-#define HAS_RGB_LED   0  // WS2812B RGB LED on GPIO0
+#define HAS_RGB_LED   GPIO_NUM_0  // WS2812B RGB LED on GPIO0
+
+// !!EXPERIMENTAL - not tested yet!!f
+// uncomment this only if your LoPy lives on a Pytrack expansion board with GPS
+// see http://www.quectel.com/UploadImage/Downlad/Quectel_L76-L_I2C_Application_Note_V1.0.pdf
+//#define HAS_GPS 1
+//#define GPS_I2C_PINS GPIO_NUM_9, GPIO_NUM_8 // SDA, SCL
+//#define GPS_I2C_ADDRESS_READ 0x21
+//#define GPS_I2C_ADDRESS_WRITE 0x20
+//#define HAS_BUTTON GPIO_NUM_4
 
 // Hardware pin definitions for Pycom LoPy4 board
-#define PIN_SPI_SS    18
-#define PIN_SPI_MOSI  27
-#define PIN_SPI_MISO  19
-#define PIN_SPI_SCK   5
+#define PIN_SPI_SS    GPIO_NUM_18
+#define PIN_SPI_MOSI  GPIO_NUM_27
+#define PIN_SPI_MISO  GPIO_NUM_19
+#define PIN_SPI_SCK   GPIO_NUM_5
 #define RST   LMIC_UNUSED_PIN
-#define DIO0  23 // LoRa IRQ
-#define DIO1  23 // workaround
+#define DIO0  GPIO_NUM_23 // LoRa IRQ
+#define DIO1  GPIO_NUM_23 // workaround
 #define DIO2  LMIC_UNUSED_PIN
 
 // select WIFI antenna (internal = onboard / external = u.fl socket)
diff --git a/src/hal/ttgobeam.h b/src/hal/ttgobeam.h
index aa3ac479..aafbb3a9 100644
--- a/src/hal/ttgobeam.h
+++ b/src/hal/ttgobeam.h
@@ -2,21 +2,21 @@
 
 #define CFG_sx1276_radio 1 // HPD13A LoRa SoC
 
-#define HAS_LED 21 // on board green LED_G1 
-// #define HAS_BUTTON GPIO_NUM_39 // button on board next to battery indicator LED (other one is reset) -> not tested yet
+#define HAS_LED GPIO_NUM_21 // on board green LED_G1
+//#define HAS_BUTTON GPIO_NUM_39 // on board button "BOOT" (next to reset button) !! seems not to work!!
 #define HAS_BATTERY_PROBE ADC1_GPIO35_CHANNEL // battery probe GPIO pin -> ADC1_CHANNEL_7
 #define BATT_FACTOR 2 // voltage divider 100k/100k on board
-// #define HAS_GPS // to be done
-// GSP serial (9600, SERIAL_8N1, 12, 15);   //17-TX 18-RX
+#define HAS_GPS 1 // use on board GPS
+#define GPS_SERIAL 9600, SERIAL_8N1, GPIO_NUM_12, GPIO_NUM_15 // UBlox NEO 6M or 7M with default configuration
 
 // re-define pin definitions of pins_arduino.h
-#define PIN_SPI_SS    18 // ESP32 GPIO18 (Pin18) -- HPD13A NSS/SEL (Pin4) SPI Chip Select Input
-#define PIN_SPI_MOSI  27 // ESP32 GPIO27 (Pin27) -- HPD13A MOSI/DSI (Pin6) SPI Data Input
-#define PIN_SPI_MISO  19 // ESP32 GPIO19 (Pin19) -- HPD13A MISO/DSO (Pin7) SPI Data Output
-#define PIN_SPI_SCK   5  // ESP32 GPIO5 (Pin5)   -- HPD13A SCK (Pin5) SPI Clock Input
+#define PIN_SPI_SS    GPIO_NUM_18 // ESP32 GPIO18 (Pin18) -- HPD13A NSS/SEL (Pin4) SPI Chip Select Input
+#define PIN_SPI_MOSI  GPIO_NUM_27 // ESP32 GPIO27 (Pin27) -- HPD13A MOSI/DSI (Pin6) SPI Data Input
+#define PIN_SPI_MISO  GPIO_NUM_19 // ESP32 GPIO19 (Pin19) -- HPD13A MISO/DSO (Pin7) SPI Data Output
+#define PIN_SPI_SCK   GPIO_NUM_5  // ESP32 GPIO5 (Pin5)   -- HPD13A SCK (Pin5) SPI Clock Input
 
 // non arduino pin definitions
 #define RST   LMIC_UNUSED_PIN // connected to ESP32 RST/EN
-#define DIO0  26 // ESP32 GPIO26 <-> HPD13A IO0
-#define DIO1  33 // Lora1 <-> HPD13A IO1 // !! NEEDS EXTERNAL WIRING !!
-#define DIO2  32 // Lora2 <-> HPD13A IO2 // needs external wiring, but not necessary for LoRa, only FSK
+#define DIO0  GPIO_NUM_26 // ESP32 GPIO26 <-> HPD13A IO0
+#define DIO1  GPIO_NUM_33 // Lora1 <-> HPD13A IO1 // !! NEEDS EXTERNAL WIRING !!
+#define DIO2  LMIC_UNUSED_PIN // Lora2 <-> HPD13A IO2 // needs external wiring, but not necessary for LoRa, only FSK
diff --git a/src/hal/ttgov1.h b/src/hal/ttgov1.h
index c8e1a12d..df5735b5 100644
--- a/src/hal/ttgov1.h
+++ b/src/hal/ttgov1.h
@@ -9,18 +9,18 @@
 #define HAS_BUTTON GPIO_NUM_0 // button "PRG" on board
 
 // re-define pin definitions of pins_arduino.h
-#define PIN_SPI_SS    18 // ESP32 GPIO18 (Pin18) -- SX1276 NSS (Pin19) SPI Chip Select Input
-#define PIN_SPI_MOSI  27 // ESP32 GPIO27 (Pin27) -- SX1276 MOSI (Pin18) SPI Data Input
-#define PIN_SPI_MISO  19 // ESP32 GPIO19 (Pin19) -- SX1276 MISO (Pin17) SPI Data Output
-#define PIN_SPI_SCK   5  // ESP32 GPIO5 (Pin5)   -- SX1276 SCK (Pin16) SPI Clock Input
+#define PIN_SPI_SS    GPIO_NUM_18 // ESP32 GPIO18 (Pin18) -- SX1276 NSS (Pin19) SPI Chip Select Input
+#define PIN_SPI_MOSI  GPIO_NUM_27 // ESP32 GPIO27 (Pin27) -- SX1276 MOSI (Pin18) SPI Data Input
+#define PIN_SPI_MISO  GPIO_NUM_19 // ESP32 GPIO19 (Pin19) -- SX1276 MISO (Pin17) SPI Data Output
+#define PIN_SPI_SCK   GPIO_NUM_5  // ESP32 GPIO5 (Pin5)   -- SX1276 SCK (Pin16) SPI Clock Input
 
 // non arduino pin definitions
-#define RST   14 // ESP32 GPIO14 (Pin14) -- SX1276 NRESET (Pin7) Reset Trigger Input
-#define DIO0  26 // ESP32 GPIO26 (Pin15) -- SX1276 DIO0 (Pin8) used by LMIC for detecting LoRa RX_Done & TX_Done
-#define DIO1  33 // ESP32 GPIO33 (Pin13) -- SX1276 DIO1 (Pin9) used by LMIC for detecting LoRa RX_Timeout
+#define RST   GPIO_NUM_14 // ESP32 GPIO14 (Pin14) -- SX1276 NRESET (Pin7) Reset Trigger Input
+#define DIO0  GPIO_NUM_26 // ESP32 GPIO26 (Pin15) -- SX1276 DIO0 (Pin8) used by LMIC for detecting LoRa RX_Done & TX_Done
+#define DIO1  GPIO_NUM_33 // ESP32 GPIO33 (Pin13) -- SX1276 DIO1 (Pin9) used by LMIC for detecting LoRa RX_Timeout
 #define DIO2  LMIC_UNUSED_PIN // 32 ESP32 GPIO32 (Pin12) -- SX1276 DIO2 (Pin10) not used by LMIC for LoRa (Timeout for FSK only)
 
 // Hardware pin definitions for TTGOv1 Board with OLED SSD1306 I2C Display
-#define OLED_RST 16 // ESP32 GPIO16 (Pin16) -- SD1306 Reset
-#define OLED_SDA 4  // ESP32 GPIO4 (Pin4)   -- SD1306 Data
-#define OLED_SCL 15 // ESP32 GPIO15 (Pin15) -- SD1306 Clock
+#define OLED_RST GPIO_NUM_16 // ESP32 GPIO16 (Pin16) -- SD1306 Reset
+#define OLED_SDA GPIO_NUM_4  // ESP32 GPIO4 (Pin4)   -- SD1306 Data
+#define OLED_SCL GPIO_NUM_15 // ESP32 GPIO15 (Pin15) -- SD1306 Clock
diff --git a/src/hal/ttgov2.h b/src/hal/ttgov2.h
index ebdfe87d..e4bb49b4 100644
--- a/src/hal/ttgov2.h
+++ b/src/hal/ttgov2.h
@@ -10,21 +10,21 @@
 #define DISABLE_BROWNOUT 1 // comment out if you want to keep brownout feature
 
 // re-define pin definitions of pins_arduino.h
-#define PIN_SPI_SS    18 // ESP32 GPIO18 (Pin18) -- HPD13A NSS/SEL (Pin4) SPI Chip Select Input
-#define PIN_SPI_MOSI  27 // ESP32 GPIO27 (Pin27) -- HPD13A MOSI/DSI (Pin6) SPI Data Input
-#define PIN_SPI_MISO  19 // ESP32 GPIO19 (Pin19) -- HPD13A MISO/DSO (Pin7) SPI Data Output
-#define PIN_SPI_SCK   5  // ESP32 GPIO5 (Pin5)   -- HPD13A SCK (Pin5) SPI Clock Input
+#define PIN_SPI_SS    GPIO_NUM_18 // ESP32 GPIO18 (Pin18) -- HPD13A NSS/SEL (Pin4) SPI Chip Select Input
+#define PIN_SPI_MOSI  GPIO_NUM_27 // ESP32 GPIO27 (Pin27) -- HPD13A MOSI/DSI (Pin6) SPI Data Input
+#define PIN_SPI_MISO  GPIO_NUM_19 // ESP32 GPIO19 (Pin19) -- HPD13A MISO/DSO (Pin7) SPI Data Output
+#define PIN_SPI_SCK   GPIO_NUM_5  // ESP32 GPIO5 (Pin5)   -- HPD13A SCK (Pin5) SPI Clock Input
 
 // non arduino pin definitions
 #define RST   LMIC_UNUSED_PIN // connected to ESP32 RST/EN
-#define DIO0  26 // ESP32 GPIO26 wired on PCB to HPD13A
-#define DIO1  33 // HPDIO1 on pcb, needs to be wired external to GPIO33
+#define DIO0  GPIO_NUM_26 // ESP32 GPIO26 wired on PCB to HPD13A
+#define DIO1  GPIO_NUM_33 // HPDIO1 on pcb, needs to be wired external to GPIO33
 #define DIO2  LMIC_UNUSED_PIN // 32 HPDIO2 on pcb, needs to be wired external to GPIO32 (not necessary for LoRa, only FSK)
 
 // Hardware pin definitions for TTGO V2 Board with OLED SSD1306 0,96" I2C Display
 #define OLED_RST U8X8_PIN_NONE // connected to CPU RST/EN
-#define OLED_SDA 21  // ESP32 GPIO4 (Pin4)   -- SD1306 D1+D2
-#define OLED_SCL 22 // ESP32 GPIO15 (Pin15) -- SD1306 D0
+#define OLED_SDA GPIO_NUM_21  // ESP32 GPIO4 (Pin4)   -- SD1306 D1+D2
+#define OLED_SCL GPIO_NUM_22 // ESP32 GPIO15 (Pin15) -- SD1306 D0
 
 
 /*
diff --git a/src/hal/ttgov21.h b/src/hal/ttgov21.h
index ebedf11b..1e3b38ec 100644
--- a/src/hal/ttgov21.h
+++ b/src/hal/ttgov21.h
@@ -4,23 +4,23 @@
 
 #define HAS_DISPLAY U8X8_SSD1306_128X64_NONAME_HW_I2C
 #define DISPLAY_FLIP  1 // rotated display
-#define HAS_LED 23 // green on board LED_G3 (not in initial board version)
+#define HAS_LED GPIO_NUM_23 // green on board LED_G3 (not in initial board version)
 #define HAS_BATTERY_PROBE ADC1_GPIO35_CHANNEL // battery probe GPIO pin -> ADC1_CHANNEL_7
 #define BATT_FACTOR 2 // voltage divider 100k/100k on board
 
 // re-define pin definitions of pins_arduino.h
-#define PIN_SPI_SS    18 // ESP32 GPIO18 (Pin18) -- HPD13A NSS/SEL (Pin4) SPI Chip Select Input
-#define PIN_SPI_MOSI  27 // ESP32 GPIO27 (Pin27) -- HPD13A MOSI/DSI (Pin6) SPI Data Input
-#define PIN_SPI_MISO  19 // ESP32 GPIO19 (Pin19) -- HPD13A MISO/DSO (Pin7) SPI Data Output
-#define PIN_SPI_SCK   5  // ESP32 GPIO5 (Pin5)   -- HPD13A SCK (Pin5) SPI Clock Input
+#define PIN_SPI_SS    GPIO_NUM_18 // ESP32 GPIO18 (Pin18) -- HPD13A NSS/SEL (Pin4) SPI Chip Select Input
+#define PIN_SPI_MOSI  GPIO_NUM_27 // ESP32 GPIO27 (Pin27) -- HPD13A MOSI/DSI (Pin6) SPI Data Input
+#define PIN_SPI_MISO  GPIO_NUM_19 // ESP32 GPIO19 (Pin19) -- HPD13A MISO/DSO (Pin7) SPI Data Output
+#define PIN_SPI_SCK   GPIO_NUM_5  // ESP32 GPIO5 (Pin5)   -- HPD13A SCK (Pin5) SPI Clock Input
 
 // non arduino pin definitions
 #define RST   LMIC_UNUSED_PIN // connected to ESP32 RST/EN
-#define DIO0  26 // ESP32 GPIO26 <-> HPD13A IO0
-#define DIO1  33 // ESP32 GPIO33 <-> HPDIO1 <-> HPD13A IO1
-#define DIO2  32 // ESP32 GPIO32 <-> HPDIO2 <-> HPD13A IO2
+#define DIO0  GPIO_NUM_26 // ESP32 GPIO26 <-> HPD13A IO0
+#define DIO1  GPIO_NUM_33 // ESP32 GPIO33 <-> HPDIO1 <-> HPD13A IO1
+#define DIO2  GPIO_NUM_32 // ESP32 GPIO32 <-> HPDIO2 <-> HPD13A IO2
 
 // Hardware pin definitions for TTGO V2 Board with OLED SSD1306 0,96" I2C Display
 #define OLED_RST U8X8_PIN_NONE // connected to CPU RST/EN
-#define OLED_SDA 21 // ESP32 GPIO4 (Pin4)   -- SD1306 D1+D2
-#define OLED_SCL 22 // ESP32 GPIO15 (Pin15) -- SD1306 D0
\ No newline at end of file
+#define OLED_SDA GPIO_NUM_21 // ESP32 GPIO4 (Pin4)   -- SD1306 D1+D2
+#define OLED_SCL GPIO_NUM_22 // ESP32 GPIO15 (Pin15) -- SD1306 D0
\ No newline at end of file
diff --git a/src/lorawan.cpp b/src/lorawan.cpp
index ec80d252..b832b311 100644
--- a/src/lorawan.cpp
+++ b/src/lorawan.cpp
@@ -109,14 +109,14 @@ void do_send(osjob_t* j){
 
     // Check if there is a pending TX/RX job running
     if (LMIC.opmode & OP_TXRXPEND) {
-        ESP_LOGI(TAG, "OP_TXRXPEND, not sending");
+        ESP_LOGI(TAG, "LoRa busy, rescheduling");
         sprintf(display_lmic, "LORA BUSY");
         goto end;
     }
 
     // prepare payload with sum of unique WIFI MACs seen
     static uint8_t mydata[4];
-  
+
     mydata[0] = (macs_wifi & 0xff00) >> 8;
     mydata[1] = macs_wifi  & 0xff;
     
@@ -129,11 +129,31 @@ void do_send(osjob_t* j){
         mydata[3] = 0;
     }
 
-    // Prepare upstream data transmission at the next possible time.
-    LMIC_setTxData2(1, mydata, sizeof(mydata), (cfg.countermode & 0x02));
-    ESP_LOGI(TAG, "Packet queued");
-    sprintf(display_lmic, "PACKET QUEUED");
+    #ifdef HAS_GPS
+        static uint8_t gpsdata[18];
+        if (cfg.gpsmode && gps.location.isValid()) {
+            gps_read();
+            memcpy (gpsdata, mydata, 4);
+            memcpy (gpsdata+4, &gps_status, sizeof(gps_status));
+            ESP_LOGI(TAG, "lat=%.6f / lon=%.6f | %u Sats | HDOP=%.1f | Altitude=%u m", \
+                gps_status.latitude / (float) 1000000, \
+                gps_status.longitude / (float) 1000000, \
+                gps_status.satellites, \
+                gps_status.hdop / (float) 100, \
+                gps_status.altitude);
+            LMIC_setTxData2(COUNTERPORT, gpsdata, sizeof(gpsdata), (cfg.countermode & 0x02));
+            ESP_LOGI(TAG, "%d bytes queued to send", sizeof(gpsdata));
+        }
+        else {
+    #endif
+            LMIC_setTxData2(COUNTERPORT, mydata, sizeof(mydata), (cfg.countermode & 0x02));
+            ESP_LOGI(TAG, "%d bytes queued to send", sizeof(mydata));
+            sprintf(display_lmic, "PACKET QUEUED");    
 
+    #ifdef HAS_GPS
+            }
+    #endif
+   
     // clear counter if not in cumulative counter mode
     if (cfg.countermode != 1) {
         reset_counters();                       // clear macs container and reset all counters
@@ -170,10 +190,6 @@ void onEvent (ev_t ev) {
             strcpy_P(buff, PSTR("JOINED"));
             sprintf(display_lora, " "); // clear previous lmic status message from display
 
-            // Disable link check validation (automatically enabled
-            // during join, but not supported by TTN at this time).  -> do we need this?
-           // LMIC_setLinkCheckMode(0);
-            
             // set data rate adaptation
             LMIC_setAdrMode(cfg.adrmode);
             // Set data rate and transmit power (note: txpower seems to be ignored by the library)
@@ -200,8 +216,9 @@ void onEvent (ev_t ev) {
                     unsigned char* buffer = new unsigned char[MAX_LEN_FRAME];
                     memcpy(buffer, LMIC.frame, MAX_LEN_FRAME); //Copy data from cfg to char*
                     int i, k = LMIC.dataBeg, l = LMIC.dataBeg+LMIC.dataLen-2;
-                    for (i=k; i<=l; i+=2)
+                    for (i=k; i<=l; i+=2) {
                         rcommand(buffer[i], buffer[i+1]);
+                    }
                     delete[] buffer; //free memory
                 }
             }
diff --git a/src/lorawan.h b/src/lorawan.h
new file mode 100644
index 00000000..de54b6e8
--- /dev/null
+++ b/src/lorawan.h
@@ -0,0 +1,10 @@
+#ifndef LORAWAN_H
+#define LORAWAN_H
+
+void onEvent(ev_t ev);
+void do_send(osjob_t* j);
+void gen_lora_deveui(uint8_t * pdeveui);
+void RevBytes(unsigned char* b, size_t c);
+void get_hard_deveui(uint8_t *pdeveui);
+
+#endif
\ No newline at end of file
diff --git a/src/macsniff.h b/src/macsniff.h
index a92046df..5eb07f30 100644
--- a/src/macsniff.h
+++ b/src/macsniff.h
@@ -1,3 +1,6 @@
+#ifndef MACSNIFF_H
+#define MACSNIFF_H
+
 // ESP32 Functions
 #include <esp_wifi.h>
 
@@ -26,3 +29,5 @@ void wifi_sniffer_packet_handler(void *buff, wifi_promiscuous_pkt_type_t type);
 
 // function defined in rokkithash.cpp
 uint32_t rokkit(const char * , int );
+
+#endif
\ No newline at end of file
diff --git a/src/main.cpp b/src/main.cpp
index 9d169e01..a6216a3c 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -39,7 +39,7 @@ Refer to LICENSE.txt file in repository for more details.
 
 // Initialize global variables
 configData_t cfg;                   // struct holds current device configuration
-osjob_t sendjob;                    // LMIC job handler
+osjob_t sendjob, rcmdjob;           // LMIC job handler
 uint64_t uptimecounter = 0;         // timer global for uptime counter
 uint8_t DisplayState = 0;           // globals for state machine
 uint16_t macs_total = 0, macs_wifi = 0, macs_ble = 0;   // MAC counters globals for display
@@ -52,13 +52,20 @@ uint16_t LEDBlinkDuration = 0;      // How long the blink need to be
 uint16_t LEDColor = COLOR_NONE;     // state machine variable to set RGB LED color
 hw_timer_t * displaytimer = NULL;   // configure hardware timer used for cyclic display refresh
 hw_timer_t * channelSwitch = NULL;  // configure hardware timer used for wifi channel switching
+xref2u1_t rcmd_data;                // buffer for rcommand results size
+u1_t rcmd_data_size;                // buffer for rcommand results size
 
-portMUX_TYPE timerMux = portMUX_INITIALIZER_UNLOCKED; // sync main loop and ISR when modifying shared variable DisplayIRQ
+#ifdef HAS_GPS
+    gpsStatus_t gps_status;         // struct for storing gps data
+    TinyGPSPlus gps;                // create TinyGPS++ instance
+#endif
+
+portMUX_TYPE timerMux = portMUX_INITIALIZER_UNLOCKED; // sync main loop and ISR when modifying IRQ handler shared variables
 
 std::set<uint16_t> macs; // associative container holds total of unique MAC adress hashes (Wifi + BLE)
 
 // this variables will be changed in the ISR, and read in main loop
-static volatile int ButtonPressed = 0, DisplayTimerIRQ = 0, ChannelTimerIRQ = 0;
+static volatile int ButtonPressedIRQ = 0, DisplayTimerIRQ = 0, ChannelTimerIRQ = 0;
 
 // local Tag for logging
 static const char TAG[] = "main";
@@ -130,37 +137,14 @@ void lorawan_loop(void * pvParameters) {
 
     configASSERT( ( ( uint32_t ) pvParameters ) == 1 ); // FreeRTOS check
 
-    //static uint16_t lorawait = 0;
-
     while(1) {
-        
-        // execute LMIC jobs
-        os_runloop_once();
-
-        /*
-        // check if payload is sent
-        while(LMIC.opmode & OP_TXRXPEND) {
-            if(!lorawait) 
-                sprintf(display_lora, "LoRa wait");
-            lorawait++;
-            // in case sending really fails: reset LMIC and rejoin network
-            if( (lorawait % MAXLORARETRY ) == 0) {
-                ESP_LOGI(TAG, "Payload not sent, resetting LMIC and rejoin");
-                lorawait = 0;                
-                LMIC_reset(); // Reset the MAC state. Session and pending data transfers will be discarded.
-            };
-            vTaskDelay(1000/portTICK_PERIOD_MS);
-        }
-        */
-
-        vTaskDelay(1/portTICK_PERIOD_MS); // reset watchdog
+        os_runloop_once();                  // execute LMIC jobs
+        vTaskDelay(1/portTICK_PERIOD_MS);   // reset watchdog
     }    
 }
 
-
 /* end LMIC specific parts --------------------------------------------------------------- */
 
-
 /* beginn hardware specific parts -------------------------------------------------------- */
 
 #ifdef HAS_DISPLAY
@@ -183,14 +167,14 @@ void lorawan_loop(void * pvParameters) {
     bool btstop = btStop();
 #endif
 
+// Button IRQ Handler Routine, IRAM_ATTR necessary here, see https://github.com/espressif/arduino-esp32/issues/855
 #ifdef HAS_BUTTON
-    // Button IRQ
-    // IRAM_ATTR necessary here, see https://github.com/espressif/arduino-esp32/issues/855
     void IRAM_ATTR ButtonIRQ() {
-        ButtonPressed++;
+        ButtonPressedIRQ++;
     }
 #endif
 
+// Wifi Channel Rotation Timer IRQ Handler Routine
 void IRAM_ATTR ChannelSwitchIRQ() {
     portENTER_CRITICAL(&timerMux);
     ChannelTimerIRQ++;
@@ -360,11 +344,14 @@ uint64_t uptime() {
 
 #ifdef HAS_BUTTON
     void readButton() {
-        if (ButtonPressed) {
-            ButtonPressed--;
+        if (ButtonPressedIRQ) {
+            portENTER_CRITICAL(&timerMux);
+            ButtonPressedIRQ--;
+            portEXIT_CRITICAL(&timerMux);
+            ESP_LOGI(TAG, "Button pressed");
             ESP_LOGI(TAG, "Button pressed, resetting device to factory defaults");
             eraseConfig();
-            esp_restart();
+            esp_restart();  
         }
     }
 #endif
@@ -483,6 +470,10 @@ void setup() {
     ESP_LOGI(TAG, "ESP32 SDK: %s", ESP.getSdkVersion());
 #endif
 
+#ifdef HAS_GPS
+    ESP_LOGI(TAG, "TinyGPS+ version %s", TinyGPSPlus::libraryVersion());
+#endif
+
     // read settings from NVRAM
     loadConfig(); // includes initialize if necessary
 
@@ -495,10 +486,8 @@ void setup() {
 #ifdef HAS_RGB_LED
     rgb_set_color(COLOR_PINK);
     strcat(features, " RGB");
-    delay(1000);
 #endif
 
-
     // initialize button handling if needed
 #ifdef HAS_BUTTON
     strcat(features, " BTN_");
@@ -521,6 +510,11 @@ void setup() {
     antenna_init();
 #endif
 
+// initialize gps if present
+#ifdef HAS_GPS
+    strcat(features, " GPS");
+#endif
+
 #ifdef HAS_DISPLAY
     strcat(features, " OLED");
     // initialize display  
@@ -588,7 +582,15 @@ xTaskCreatePinnedToCore(sniffer_loop, "wifisniffer", 2048, ( void * ) 1, 1, NULL
         start_BLEscan();
     }
 #endif
-    
+
+// if device has GPS and GPS function is enabled, start GPS reader task on core 0
+#ifdef HAS_GPS
+    if (cfg.gpsmode) {
+        ESP_LOGI(TAG, "Starting GPS task on core 0");
+        xTaskCreatePinnedToCore(gps_loop, "gpsfeed", 2048, ( void * ) 1, 1, NULL, 0);
+    }
+#endif
+
 // kickoff sendjob -> joins network and rescedules sendjob for cyclic transmitting payload
 do_send(&sendjob);
 
@@ -627,6 +629,12 @@ void loop() {
             reset_salt();       // get new salt for salting hashes
         }
 
+        #ifdef HAS_GPS
+            // log NMEA status every 30 seconds, useful for debugging GPS connection
+            if ( (uptime() % 30000) == 0 )
+                ESP_LOGD(TAG, "GPS NMEA data: passed %d / failed: %d / with fix: %d", gps.passedChecksum(), gps.failedChecksum(), gps.sentencesWithFix());
+        #endif
+
         vTaskDelay(1/portTICK_PERIOD_MS); // reset watchdog
 
     } // end of infinite main loop
diff --git a/src/main.h b/src/main.h
index d0ba04c2..a2e0eeb0 100644
--- a/src/main.h
+++ b/src/main.h
@@ -1,6 +1,10 @@
 
+#include "configmanager.h"
+#include "lorawan.h"
+#include "macsniff.h"
+
 // program version - note: increment version after modifications to configData_t struct!!
-#define PROGVERSION                     "1.3.71"    // use max 10 chars here!
+#define PROGVERSION                     "1.3.8"    // use max 10 chars here!
 #define PROGNAME                        "PAXCNT"
 
 //--- Declarations ---
@@ -23,25 +27,15 @@ void reset_counters(void);
 void blink_LED(uint16_t set_color, uint16_t set_blinkduration);
 void led_loop(void);
 
-// defined in configmanager.cpp
-void eraseConfig(void);
-void saveConfig(void);
-void loadConfig(void);
-
-// defined in lorawan.cpp
-void onEvent(ev_t ev);
-void do_send(osjob_t* j);
-void gen_lora_deveui(uint8_t * pdeveui);
-void RevBytes(unsigned char* b, size_t c);
-void get_hard_deveui(uint8_t *pdeveui);
-
-// defined in wifisniffer.cpp
-void wifi_sniffer_init(void);
-void wifi_sniffer_set_channel(uint8_t channel);
-void wifi_sniffer_packet_handler(void *buff, wifi_promiscuous_pkt_type_t type);
 
 // defined in blescan.cpp
 #ifdef BLECOUNTER
-    void start_BLEscan(void);
-    void stop_BLEscan(void);
+  void start_BLEscan(void);
+  void stop_BLEscan(void);
+#endif
+
+//defined in gpsread.cpp
+#ifdef HAS_GPS
+  void gps_read(void);
+  void gps_loop(void * pvParameters);
 #endif
\ No newline at end of file
diff --git a/src/paxcounter.conf b/src/paxcounter.conf
index bc709486..47432573 100644
--- a/src/paxcounter.conf
+++ b/src/paxcounter.conf
@@ -37,11 +37,14 @@
 // LoRa payload send cycle --> take care of duty cycle of LoRaWAN network! <--
 #define SEND_SECS                       120     // [seconds/2] -> 240 sec.
 #define MEM_LOW                         2048    // [Bytes] low memory threshold triggering a send cycle
+#define RETRANSMIT_RCMD                 5       // [seconds] wait time before retransmitting rcommand results
 
 // Default LoRa Spreadfactor
 #define LORASFDEFAULT                   9       // 7 ... 12 SF, according to LoRaWAN specs
 #define MAXLORARETRY                    500     // maximum count of TX retries if LoRa busy
 #define RCMDPORT                        2       // LoRaWAN Port on which device listenes for remote commands
+#define GPSPORT                         3       // LoRaWAN Port on which device sends gps data
+#define COUNTERPORT                     1       // LoRaWAN Port on which device sends counts
 
 // Default RGB LED luminosity (in %)
 #define RGBLUMINOSITY                   30      // 30%
diff --git a/src/rcommand.cpp b/src/rcommand.cpp
index 816820c5..fa061f9f 100644
--- a/src/rcommand.cpp
+++ b/src/rcommand.cpp
@@ -29,6 +29,25 @@ typedef struct {
     uint32_t read_voltage(void);
 #endif
 
+// function sends result of get commands to LoRaWAN network
+void do_transmit(osjob_t* j){
+    // check if there is a pending TX/RX job running, if yes then reschedule transmission
+    if (LMIC.opmode & OP_TXRXPEND) {
+        ESP_LOGI(TAG, "LoRa busy, rescheduling");
+        sprintf(display_lmic, "LORA BUSY");
+        os_setTimedCallback(&rcmdjob, os_getTime()+sec2osticks(RETRANSMIT_RCMD), do_transmit);
+    }
+    LMIC_setTxData2(RCMDPORT, rcmd_data, rcmd_data_size, 0); // send data unconfirmed on RCMD Port
+    ESP_LOGI(TAG, "%d bytes queued to send", rcmd_data_size);
+    sprintf(display_lmic, "PACKET QUEUED");
+}
+
+// help function to transmit result of get commands, since callback function do_transmit() cannot have params
+void transmit(xref2u1_t mydata, u1_t mydata_size){
+    rcmd_data = mydata;
+    rcmd_data_size = mydata_size;
+    do_transmit(&rcmdjob);
+}
 
 // help function to assign LoRa datarates to numeric spreadfactor values
 void switch_lora (uint8_t sf, uint8_t tx) {
@@ -141,6 +160,14 @@ void set_display(uint8_t val) {
         }
 };
 
+void set_gps(uint8_t val) {
+    ESP_LOGI(TAG, "Remote command: set GPS to %s", val ? "on" : "off");
+    switch (val) {
+        case 1: cfg.gpsmode = val; break;
+        default: cfg.gpsmode = 0; break;
+        }
+};
+
 void set_lorasf(uint8_t val) {
     ESP_LOGI(TAG, "Remote command: set LoRa SF to %d", val);
     switch_lora(val, cfg.txpower);
@@ -204,30 +231,20 @@ void set_lorapower(uint8_t val) {
     switch_lora(cfg.lorasf, val);
 };
 
-void set_noop (uint8_t val) { 
-    ESP_LOGI(TAG, "Remote command: noop - doing nothing");
-};
-
 void get_config (uint8_t val) {
     ESP_LOGI(TAG, "Remote command: get configuration");
-    int size = sizeof(configData_t);
-    LMIC_setTxData2(RCMDPORT, (byte*)&cfg, size, 0); // send data unconfirmed on RCMD Port
-    ESP_LOGI(TAG, "%d bytes queued in send queue", size);
+    transmit((byte*)&cfg, sizeof(cfg));
 };
 
 void get_uptime (uint8_t val) {
     ESP_LOGI(TAG, "Remote command: get uptime");
-    int size = sizeof(uptimecounter);
-    LMIC_setTxData2(RCMDPORT, (byte*)&uptimecounter, size, 0); // send data unconfirmed on RCMD Port
-    ESP_LOGI(TAG, "%d bytes queued in send queue", size);
+    transmit((byte*)&uptimecounter, sizeof(uptimecounter));
 };
 
 void get_cputemp (uint8_t val) {
     ESP_LOGI(TAG, "Remote command: get cpu temperature");
     float temp = temperatureRead();
-    int size = sizeof(temp);
-    LMIC_setTxData2(RCMDPORT, (byte*)&temp, size, 0); // send data unconfirmed on RCMD Port
-    ESP_LOGI(TAG, "%d bytes queued in send queue", size);
+    transmit((byte*)&temp, sizeof(temp));
 };
 
 void get_voltage (uint8_t val) {
@@ -237,11 +254,19 @@ void get_voltage (uint8_t val) {
     #else
         uint16_t voltage = 0;
     #endif
-    int size = sizeof(voltage);
-    LMIC_setTxData2(RCMDPORT, (byte*)&voltage, size, 0); // send data unconfirmed on RCMD Port
-    ESP_LOGI(TAG, "%d bytes queued in send queue", size);
+    transmit((byte*)&voltage, sizeof(voltage));
 };
 
+void get_gps (uint8_t val) {
+    ESP_LOGI(TAG, "Remote command: get gps status");
+    #ifdef HAS_GPS
+        gps_read();
+        transmit((byte*)&gps_status, sizeof(gps_status));
+        ESP_LOGI(TAG, "lat=%f / lon=%f | Sats=%u | HDOP=%u | Alti=%u", gps_status.latitude / 1000000, gps_status.longitude / 1000000, gps_status.satellites, gps_status.hdop, gps_status.altitude);
+    #else
+        ESP_LOGE(TAG, "GPS not present");
+    #endif
+};
 
 // assign previously defined functions to set of numeric remote commands
 // format: opcode, function, flag (1 = do make settings persistent / 0 = don't)
@@ -249,7 +274,7 @@ void get_voltage (uint8_t val) {
 cmd_t table[] = {
                 {0x01, set_rssi, true},
                 {0x02, set_countmode, true},
-                {0x03, set_noop, false},
+                {0x03, set_gps, true},
                 {0x04, set_display, true},
                 {0x05, set_lorasf, true},
                 {0x06, set_lorapower, true},
@@ -266,7 +291,8 @@ cmd_t table[] = {
                 {0x80, get_config, false},
                 {0x81, get_uptime, false},
                 {0x82, get_cputemp, false},
-                {0x83, get_voltage, false}
+                {0x83, get_voltage, false},
+                {0x84, get_gps, false}
                 };
 
 // check and execute remote command