diff --git a/code/espurna/config/arduino.h b/code/espurna/config/arduino.h
index 635c8abf..d1a1de6e 100644
--- a/code/espurna/config/arduino.h
+++ b/code/espurna/config/arduino.h
@@ -254,3 +254,4 @@
 //#define V9261F_SUPPORT         1
 //#define VEML6075_SUPPORT       1
 //#define VL53L1X_SUPPORT        1
+//#define HDC1080_SUPPORT        1
diff --git a/code/espurna/config/sensors.h b/code/espurna/config/sensors.h
index 3f583aaa..045c1f1d 100644
--- a/code/espurna/config/sensors.h
+++ b/code/espurna/config/sensors.h
@@ -1057,6 +1057,19 @@
 #define SI7021_ADDRESS                  0x00    // 0x00 means auto
 #endif
 
+//------------------------------------------------------------------------------
+// HDC1080 / 831R temperature & humidity sensor
+// Enable support by passing HDC1080_SUPPORT=1 build flag
+//------------------------------------------------------------------------------
+
+#ifndef HDC1080_SUPPORT
+#define HDC1080_SUPPORT                  0
+#endif
+
+#ifndef HDC1080_ADDRESS
+#define HDC1080_ADDRESS                  0x00    // 0x00 means auto
+#endif
+
 //------------------------------------------------------------------------------
 // Sonar
 // Enable support by passing SONAR_SUPPORT=1 build flag
@@ -1310,7 +1323,8 @@
     SI1145_SUPPORT || \
     SI7021_SUPPORT || \
     VEML6075_SUPPORT || \
-    VL53L1X_SUPPORT \
+    VL53L1X_SUPPORT || \
+    HDC1080_SUPPORT \
 )
 #undef I2C_SUPPORT
 #define I2C_SUPPORT                 1
@@ -1372,7 +1386,8 @@
     TMP3X_SUPPORT || \
     V9261F_SUPPORT || \
     VEML6075_SUPPORT || \
-    VL53L1X_SUPPORT \
+    VL53L1X_SUPPORT || \
+    HDC1080_SUPPORT \
 )
 #endif
 
diff --git a/code/espurna/config/types.h b/code/espurna/config/types.h
index 47959d56..f5b2421a 100644
--- a/code/espurna/config/types.h
+++ b/code/espurna/config/types.h
@@ -331,6 +331,7 @@
 #define SENSOR_ADE7953_ID           37
 #define SENSOR_T6613_ID             38
 #define SENSOR_SI1145_ID            39
+#define SENSOR_HDC1080_ID           40
 
 //--------------------------------------------------------------------------------
 // Magnitudes
diff --git a/code/espurna/sensor.h b/code/espurna/sensor.h
index 846af9e8..a59350cc 100644
--- a/code/espurna/sensor.h
+++ b/code/espurna/sensor.h
@@ -315,5 +315,8 @@ void sensorLoop();
     #include "sensors/SI1145Sensor.h"
 #endif
 
+#if HDC1080_SUPPORT
+    #include "sensors/HDC1080Sensor.h"
+#endif
 //--------------------------------------------------------------------------------
 
diff --git a/code/espurna/sensor.ino b/code/espurna/sensor.ino
index 516a40be..52f7b20c 100644
--- a/code/espurna/sensor.ino
+++ b/code/espurna/sensor.ino
@@ -1548,6 +1548,13 @@ void _sensorLoad() {
     }
     #endif
 
+    #if HDC1080_SUPPORT
+    {
+        HDC1080Sensor * sensor = new HDC1080Sensor();
+        sensor->setAddress(HDC1080_ADDRESS);
+        _sensors.push_back(sensor);
+    }
+    #endif
 }
 
 void _sensorCallback(unsigned char i, unsigned char type, double value) {
diff --git a/code/espurna/sensors/HDC1080Sensor.h b/code/espurna/sensors/HDC1080Sensor.h
new file mode 100644
index 00000000..b7c7d31a
--- /dev/null
+++ b/code/espurna/sensors/HDC1080Sensor.h
@@ -0,0 +1,162 @@
+// -----------------------------------------------------------------------------
+// HDC1080 / 831R Sensor over I2C
+// Based on SI7021 / HTU21D Sensor over I2C
+// Copyright (C) 2017-2019 by Xose Pérez <xose dot perez at gmail dot com>
+// Copyright (C) 2020 by Alexander Kolesnikov <vtochq at gmail dot com>
+// -----------------------------------------------------------------------------
+
+#if SENSOR_SUPPORT && HDC1080_SUPPORT
+
+#pragma once
+
+#include <Arduino.h>
+
+#include "I2CSensor.h"
+#include "../utils.h"
+
+#define HDC1080_SCL_FREQUENCY    200
+
+// Middle byte of Device Serial ID. May be diffirent on your chip (see debug i2c.scan)
+#define HDC1080_CHIP_HDC1080     0x2C
+
+#define HDC1080_CMD_TMP     0x00
+#define HDC1080_CMD_HUM     0x01
+
+PROGMEM const char hdc1080_chip_hdc1080_name[] = "HDC1080";
+
+class HDC1080Sensor : public I2CSensor<> {
+
+    public:
+
+        // ---------------------------------------------------------------------
+        // Public
+        // ---------------------------------------------------------------------
+
+        HDC1080Sensor() {
+            _sensor_id = SENSOR_HDC1080_ID;
+        }
+
+        // ---------------------------------------------------------------------
+        // Sensor API
+        // ---------------------------------------------------------------------
+
+        // Initialization method, must be idempotent
+        void begin() {
+            if (!_dirty) return;
+            _init();
+            _dirty = !_ready;
+        }
+
+        // Descriptive name of the sensor
+        String description() {
+            char name[10];
+            strncpy_P(name, hdc1080_chip_hdc1080_name, sizeof(name));
+            char buffer[25];
+            snprintf(buffer, sizeof(buffer), "%s @ I2C (0x%02X)", name, _address);
+            return String(buffer);
+        }
+
+        // Descriptive name of the slot # index
+        String slot(unsigned char index) {
+            return description();
+        };
+
+        // Type for slot # index
+        unsigned char type(unsigned char index) {
+            if (index == 0) return MAGNITUDE_TEMPERATURE;
+            if (index == 1) return MAGNITUDE_HUMIDITY;
+            return MAGNITUDE_NONE;
+        }
+
+        // Pre-read hook (usually to populate registers with up-to-date data)
+        void pre() {
+
+            _error = SENSOR_ERROR_UNKNOWN_ID;
+            if (_chip == 0) return;
+            _error = SENSOR_ERROR_OK;
+
+            double value;
+
+            value = _read(HDC1080_CMD_TMP);
+            if (_error != SENSOR_ERROR_OK) return;
+            _temperature = (165 * value / 65536) - 40;
+
+            value = _read(HDC1080_CMD_HUM);
+            if (_error != SENSOR_ERROR_OK) return;
+            value = (value / 65536)*100;
+            _humidity = constrain(value, 0, 100);
+        }
+
+        // Current value for slot # index
+        double value(unsigned char index) {
+            if (index == 0) return _temperature;
+            if (index == 1) return _humidity;
+            return 0;
+        }
+
+    protected:
+
+        // ---------------------------------------------------------------------
+        // Protected
+        // ---------------------------------------------------------------------
+
+        void _init() {
+
+            // I2C auto-discover
+            unsigned char addresses[] = {0x40};
+            _address = _begin_i2c(_address, sizeof(addresses), addresses);
+            if (_address == 0) return;
+
+            // Check device
+            i2c_write_uint8(_address, 0xFC, 0xC9);
+            _chip = i2c_read_uint8(_address);
+
+            if (_chip != HDC1080_CHIP_HDC1080) {
+
+                _count = 0;
+                i2cReleaseLock(_address);
+                _previous_address = 0;
+                _error = SENSOR_ERROR_UNKNOWN_ID;
+
+                // Setting _address to 0 forces auto-discover
+                // This might be necessary at this stage if there is a
+                // different sensor in the hardcoded address
+                _address = 0;
+
+            } else {
+                _count = 2;
+            }
+
+            _ready = true;
+
+        }
+
+        unsigned int _read(uint8_t command) {
+
+            // Request measurement
+            i2c_write_uint8(_address, command);
+
+            // When not using clock stretching (*_NOHOLD commands) delay here
+            // is needed to wait for the measurement.
+            // According to datasheet the max. conversion time is ~22ms
+            nice_delay(50);
+
+            // Clear the last to bits of LSB to 00.
+            // According to datasheet LSB of Temp and RH is always xxxxxx00
+            unsigned int value = i2c_read_uint16(_address) & 0xFFFC;
+
+            // We should be checking there are no pending bytes in the buffer
+            // and raise a CRC error if there are
+            _error = SENSOR_ERROR_OK;
+
+            return value;
+
+        }
+
+        unsigned char _chip;
+        double _temperature = 0;
+        double _humidity = 0;
+
+};
+
+#endif // SENSOR_SUPPORT && HDC1080_SUPPORT
diff --git a/code/espurna/utils.ino b/code/espurna/utils.ino
index ab91423c..b5694e30 100644
--- a/code/espurna/utils.ino
+++ b/code/espurna/utils.ino
@@ -248,9 +248,9 @@ void heartbeat() {
     if (serial) {
         infoUptime();
         infoHeapStats();
-        #if ADC_MODE_VALUE == ADC_VCC
+        if (ADC_MODE_VALUE == ADC_VCC) {
             DEBUG_MSG_P(PSTR("[MAIN] Power: %lu mV\n"), ESP.getVcc());
-        #endif
+        }
         #if NTP_SUPPORT
             if (ntpSynced()) DEBUG_MSG_P(PSTR("[MAIN] Time: %s\n"), (char *) ntpDateTime().c_str());
         #endif
@@ -548,9 +548,9 @@ void info(bool first) {
         DEBUG_MSG_P(PSTR("[MAIN] Firmware MD5: %s\n"), (char *) ESP.getSketchMD5().c_str());
     }
 
-    #if ADC_MODE_VALUE == ADC_VCC
+    if (ADC_MODE_VALUE == ADC_VCC) {
         DEBUG_MSG_P(PSTR("[MAIN] Power: %u mV\n"), ESP.getVcc());
-    #endif
+    }
     if (espurnaLoopDelay()) {
         DEBUG_MSG_P(PSTR("[MAIN] Power saving delay value: %lu ms\n"), espurnaLoopDelay());
     }
diff --git a/code/espurna/ws.ino b/code/espurna/ws.ino
index a3e2d567..d25129a4 100644
--- a/code/espurna/ws.ino
+++ b/code/espurna/ws.ino
@@ -358,9 +358,11 @@ void _wsUpdate(JsonObject& root) {
     root["uptime"] = getUptime();
     root["rssi"] = WiFi.RSSI();
     root["loadaverage"] = systemLoadAverage();
-    #if ADC_MODE_VALUE == ADC_VCC
+    if (ADC_MODE_VALUE == ADC_VCC) {
         root["vcc"] = ESP.getVcc();
-    #endif
+    } else {
+        root["vcc"] = "N/A (TOUT) ";
+    }
     #if NTP_SUPPORT
         if (ntpSynced()) root["now"] = now();
     #endif
diff --git a/code/test/build/sensor.h b/code/test/build/sensor.h
index 10bf6e1f..59ca771f 100644
--- a/code/test/build/sensor.h
+++ b/code/test/build/sensor.h
@@ -28,3 +28,4 @@
 #define TMP3X_SUPPORT 1
 #define VEML6075_SUPPORT 1
 #define VL53L1X_SUPPORT 1
+#define HDC1080_SUPPORT 1