diff --git a/platformio.ini b/platformio.ini
index 9adc4d0..15fe179 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -37,6 +37,10 @@ build_flags =
     -D dataTCS34725_lux_minchange=20
     -D dataTCS34725_colortemp_minchange=100
 
+    -D SENSOR_HS1101
+    -D HS1101PIN=D5
+    -D dataHS1101_minchange=2
+
 lib_deps = 
     Adafruit BMP085 Library@1.1.0
     https://github.com/adafruit/Adafruit_TCS34725
diff --git a/src/main.cpp b/src/main.cpp
index c5ac3ae..dc37c9d 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -51,6 +51,17 @@ struct sensordata
   float value_pressureBMP=0;
 #endif
 
+#ifdef SENSOR_HS1101
+  struct sensordata dataHS1101;
+  float value_humidityHS1101=0;
+  #define HUMARRAYSIZE 11
+  //from HS1101 datasheet https://www.parallax.com/sites/default/files/downloads/27920-Humidity-Sensor-Datasheet.pdf
+  static const unsigned int out_humidity[] = {1000,900,800,700,600,500,400,300,200,100,0};  //*10, gets later devided by 10
+  static const unsigned int in_hs1101frequency[]  = {6033,6186,6330,6468,6600,6728,6853,6976,7100,7224,7351};
+  float getHumidity_HS1101(int pin);
+  int get_mapped(const unsigned int* _in, const unsigned int* _out, byte size,int val);
+#endif
+
 #ifdef SENSOR_BH1750
   //SCL=D1, SDA=D2
   #include <Wire.h>
@@ -154,6 +165,7 @@ struct sensordata
 
 #ifdef SENSOR_TCS34725
   #include "Adafruit_TCS34725.h"
+  //Connect SCL to D1, SDA to D2, GND and 3v3
   Adafruit_TCS34725 tcs = Adafruit_TCS34725(TCS34725_INTEGRATIONTIME_700MS, TCS34725_GAIN_1X);
   bool tcs34725init_ok=false;
   struct sensordata dataTCS34725_lux;
@@ -212,6 +224,13 @@ void setup() {
     #endif
   #endif
 
+  #ifdef SENSOR_HS1101
+    Serial.println("initializing hs1101");
+    #ifdef dataHS1101_minchange
+      dataHS1101.minchange=dataHS1101_minchange;
+    #endif
+  #endif
+
   #ifdef SENSOR_BH1750
     Serial.println("initializing bh1750");
     Wire.begin();  
@@ -321,6 +340,14 @@ void setup() {
     sensorNode.advertise("humidity");
   #endif
 
+  #ifdef SENSOR_HS1101
+    #if defined(SENSOR_DHT22)
+      sensorNode.advertise("humidity_hs1101");
+    #else
+      sensorNode.advertise("humidity");
+    #endif
+  #endif
+
   #ifdef SENSOR_BH1750
     sensorNode.advertise("light");
     lightMeter.readLightLevel(); //make first reading, could be 0
@@ -494,6 +521,41 @@ void loop_BMP180_pressure()
 }
 #endif
 
+#ifdef SENSOR_HS1101
+void loop_HS1101() {
+  
+
+  sensordata &d=dataHS1101;
+  
+  bool _changed=false;
+  if (millis() >= (d.lastreadtime+d.readdelay)) {
+    value_humidityHS1101 = getHumidity_HS1101(HS1101PIN); //hum %
+    if (fabs(d.lastsentvalue-value_humidityHS1101)>=d.minchange){
+      _changed=true;
+    }
+    d.lastreadtime=millis();
+  }
+
+  if (_changed || millis() >= (d.lastsent+d.senddelaymax)) {
+    Serial.print("Sending HS1101. reason=");
+    if (_changed) Serial.println("change"); else Serial.println("time");
+    checkESPStatus();
+
+    #if defined(SENSOR_DHT22)
+      Homie.getLogger() << "humidity hs1101 " << ": " << value_humidityHS1101 << endl;
+      sensorNode.setProperty("humidity_hs1101").send(String(value_humidityHS1101));
+    #else
+      Homie.getLogger() << "humidity " << ": " << value_humidityHS1101 << endl;
+      sensorNode.setProperty("humidity").send(String(value_humidityHS1101));
+    #endif
+    
+    d.lastsentvalue=value_humidityHS1101;
+    
+    d.lastsent=millis();
+  }
+}
+#endif
+
 #ifdef SENSOR_BH1750
 void loop_BH1750()
 {
@@ -768,6 +830,10 @@ void loopHandler() {
     }
   #endif
 
+  #ifdef SENSOR_HS1101
+    loop_HS1101();
+  #endif
+
   #ifdef SENSOR_BH1750
     if (bh1750init_ok) {
       loop_BH1750();
@@ -933,4 +999,40 @@ void readSDS018()
     sds018_swSerial.flush();
   }
 }
-#endif
\ No newline at end of file
+#endif
+
+#ifdef SENSOR_HS1101
+float getHumidity_HS1101(int pin) {
+  #define HS1101_SAMPLES 512
+  double freq = 0;
+  //for(unsigned int j=0; j<SAMPLES; j++) freq+= 500000/pulseIn(pin, LOW, 1000);
+  for(unsigned int j=0; j<HS1101_SAMPLES; j++) freq+= 1000000/(pulseIn(pin, HIGH, 1000)+pulseIn(pin, LOW, 1000)); //both high and low because signal has not 50% duty cycle
+  freq=freq / HS1101_SAMPLES;
+  if (freq>2000 && freq<10000){ //in roughly valid range
+    return get_mapped(in_hs1101frequency,out_humidity,HUMARRAYSIZE, freq )/10.0;
+  }else{ //error
+    return -1;
+  }
+}
+
+
+//quelle: https://groups.google.com/forum/#!topic/souliss/1kMAltPB2ME[1-25]
+int get_mapped(const unsigned int* _in, const unsigned int* _out, byte size,int val) //map with constrain
+{ 
+ // take care the value is within range
+ // val = constrain(val, _in[0], _in[size-1]);
+ 
+ if (val <= _in[0]) return _out[0];
+ if (val >= _in[size-1]) return _out[size-1];
+
+ // search right interval
+ byte pos = 1;  // _in[0] allready tested
+ while(val > _in[pos]) pos++;
+
+ // this will handle all exact "points" in the _in array
+ if (val == _in[pos]) return _out[pos];
+
+ // interpolate in the right segment for the rest
+ return map(val, _in[pos-1], _in[pos], _out[pos-1], _out[pos]);
+}
+#endif