diff --git a/lib/SDS011/src/SDS011.cpp b/lib/SDS011/src/SDS011.cpp
new file mode 100644
index 00000000..31efdea4
--- /dev/null
+++ b/lib/SDS011/src/SDS011.cpp
@@ -0,0 +1,191 @@
+// SDS011 dust sensor PM2.5 and PM10
+// ---------------------
+//
+// By R. Zschiegner (rz@madavi.de)
+// April 2016
+//
+// Documentation:
+//    - The iNovaFitness SDS011 datasheet
+//
+// modified by AQ - 2018-11-18
+//
+
+#include "SDS011.h"
+
+static const byte SDS_SLEEP[] = {
+  0xAA, // head
+  0xB4, // command id
+  0x06, // data byte 1
+  0x01, // data byte 2 (set mode)
+  0x00, // data byte 3 (sleep)
+  0x00, // data byte 4
+  0x00, // data byte 5
+  0x00, // data byte 6
+  0x00, // data byte 7
+  0x00, // data byte 8
+  0x00, // data byte 9
+  0x00, // data byte 10
+  0x00, // data byte 11
+  0x00, // data byte 12
+  0x00, // data byte 13
+  0xFF, // data byte 14 (device id byte 1)
+  0xFF, // data byte 15 (device id byte 2)
+  0x05, // checksum
+  0xAB  // tail
+};
+
+static const byte SDS_START[] = {
+  0xAA, 0xB4, 0x06, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0x06, 0xAB};
+
+static const byte SDS_CONT_MODE[] = {
+  0xAA, 0xB4, 0x08, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0x07, 0xAB};
+  
+static const byte SDS_VERSION[] = {
+  0xAA, 0xB4, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xFF, 0xFF, 0x05, 0xAB};
+
+const uint8_t SDS_cmd_len = 19;
+
+SDS011::SDS011(void) {
+
+}
+
+// --------------------------------------------------------
+// SDS011:read
+// --------------------------------------------------------
+int SDS011::read(float *p25, float *p10) {
+  byte buffer;
+  int value;
+  int len = 0;
+  int pm10_serial = 0;
+  int pm25_serial = 0;
+  int checksum_is;
+  int checksum_ok = 0;
+  int error = 1;
+  
+  while ((sds_data->available() > 0) && (sds_data->available() >= (10-len))) {
+    buffer = sds_data->read();
+    value = int(buffer);
+    switch (len) {
+      case (0): if (value != 170) { len = -1; }; break;
+      case (1): if (value != 192) { len = -1; }; break;
+      case (2): pm25_serial = value; checksum_is = value; break;
+      case (3): pm25_serial += (value << 8); checksum_is += value; break;
+      case (4): pm10_serial = value; checksum_is += value; break;
+      case (5): pm10_serial += (value << 8); checksum_is += value; break;
+      case (6): checksum_is += value; break;
+      case (7): checksum_is += value; break;
+      case (8): if (value == (checksum_is % 256)) { checksum_ok = 1; } else { len = -1; }; break;
+      case (9): if (value != 171) { len = -1; }; break;
+    }
+    len++;
+    if (len == 10 && checksum_ok == 1) {
+      *p10 = (float)pm10_serial/10.0;
+      *p25 = (float)pm25_serial/10.0;
+      len = 0; checksum_ok = 0; pm10_serial = 0.0; pm25_serial = 0.0; checksum_is = 0;
+      error = 0;
+    }
+    yield();
+  }
+  return error;
+}
+
+// --------------------------------------------------------
+// SDS011:sleep
+// --------------------------------------------------------
+void SDS011::sleep() {
+    SDS_cmd(SDS_STOP_CMD);
+}
+
+// --------------------------------------------------------
+// SDS011:wakeup
+// --------------------------------------------------------
+void SDS011::wakeup() {
+    SDS_cmd(SDS_START_CMD);
+}
+
+// --------------------------------------------------------
+// SDS011:continous mode
+// --------------------------------------------------------
+void SDS011::contmode(int noOfMinutes)
+{
+     byte buffer[SDS_cmd_len];
+     memcpy(buffer, SDS_CONT_MODE, SDS_cmd_len);
+     buffer[4] = (byte) noOfMinutes;
+     buffer[17] = calcChecksum( buffer );
+    for (uint8_t i = 0; i < SDS_cmd_len; i++) {
+         sds_data->write(buffer[i]);
+    }
+    sds_data->flush();
+    while (sds_data->available() > 0) {
+        sds_data->read();
+    }    
+//     SDS_cmd(SDS_CONTINUOUS_MODE_CMD); 
+}
+
+/*****************************************************************
+ * send SDS011 command (start, stop, continuous mode, version    *
+ *****************************************************************/
+void SDS011::SDS_cmd(const uint8_t cmd) 
+{
+    byte buf[SDS_cmd_len];
+    switch (cmd) {
+    case SDS_START_CMD:
+      memcpy(buf, SDS_START, SDS_cmd_len);
+      break;
+    case SDS_STOP_CMD:
+      memcpy(buf, SDS_SLEEP, SDS_cmd_len);
+      break;
+    case SDS_CONTINUOUS_MODE_CMD:
+      memcpy(buf, SDS_CONT_MODE, SDS_cmd_len);
+      break;
+    case SDS_VERSION_DATE_CMD:
+      memcpy(buf, SDS_VERSION, SDS_cmd_len);
+      break;
+    default:
+        return;
+    }
+    for (uint8_t i = 0; i < SDS_cmd_len; i++) {
+         sds_data->write(buf[i]);
+    }
+    sds_data->flush();
+    while (sds_data->available() > 0) {
+        sds_data->read();
+    }     
+
+}
+
+// --------------------------------------------------------
+// SDS011: calculate checksum
+// --------------------------------------------------------
+uint8_t SDS011::calcChecksum( byte *buffer )
+{
+  uint8_t value = 0;
+
+  for (uint8_t i = 2; i < 17; i++ )
+  {
+      value += buffer[i];
+      value &= 0xff;
+  }
+  return value;
+}
+
+void SDS011::begin(uint8_t pin_rx, uint8_t pin_tx) {
+  _pin_rx = pin_rx;
+  _pin_tx = pin_tx;
+
+  SoftwareSerial *softSerial = new SoftwareSerial(_pin_rx, _pin_tx);
+  softSerial->begin(9600);
+
+  sds_data = softSerial;
+}
+
+void SDS011::begin(HardwareSerial* serial) {
+  Serial.println("SDS011::begin");
+//  serial->begin(9600);    // why do I have to remove this line?
+  sds_data = serial;
+}
+
+void SDS011::begin(SoftwareSerial* serial) {
+  serial->begin(9600);
+  sds_data = serial;
+}