diff --git a/include/mgos_si7021.h b/include/mgos_si7021.h
new file mode 100644
index 0000000..425b57e
--- /dev/null
+++ b/include/mgos_si7021.h
@@ -0,0 +1,46 @@
+#pragma once
+
+#include "mgos.h"
+#include "mgos_i2c.h"
+
+#define MGOS_SI7021_READ_DELAY (2)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct mgos_si7021;
+
+/*
+ *
+ */
+struct mgos_si7021 *mgos_si7021_create(struct mgos_i2c *i2c, uint8_t i2caddr);
+
+/*
+ *
+ */
+void mgos_si7021_destroy(struct mgos_si7021 **sensor);
+
+/*
+ *
+ */
+bool mgos_si7021_read(struct mgos_si7021 *sensor);
+
+/*
+ *
+ */
+float mgos_si7021_getTemperature(struct mgos_si7021 *sensor);
+
+/*
+ *
+ */
+float mgos_si7021_getHumidity(struct mgos_si7021 *sensor);
+
+/*
+ *
+ */
+bool mgos_si7021_i2c_init(void);
+
+#ifdef __cplusplus
+}
+#endif
diff --git a/mgos_si7021.c b/mgos_si7021.c
new file mode 100644
index 0000000..e69de29
diff --git a/src/main.c b/src/main.c
index b810cb7..eafe0ae 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,6 +1,7 @@
 #include "mgos.h"
 #include "mgos_i2c.h"
 #include "mgos_sht31.h"
+#include "mgos_si7021.h"
 #include <fcntl.h>
 #include <sys/ioctl.h>
 
@@ -37,25 +38,37 @@ bool i2c_dumpregs(struct mgos_i2c *i2c, uint8_t i2caddr) {
 bool sht31(struct mgos_i2c *i2c, uint8_t i2caddr) {
   struct mgos_sht31 *sht31;
   float temp, humid;
-  int num;
 
   if (!(sht31 = mgos_sht31_create(i2c, i2caddr))) {
     LOG(LL_ERROR, ("Cannot create SHT31 device"));
     return false;
   }
 
-  num=1000;
-  while (num--) {
-    temp=mgos_sht31_getTemperature(sht31);
-    humid=mgos_sht31_getHumidity(sht31);
-    LOG(LL_INFO, ("SHT31: temperature=%.2fC humidity=%.1f%%", temp, humid));
-    sleep(1);
-  }
+  temp=mgos_sht31_getTemperature(sht31);
+  humid=mgos_sht31_getHumidity(sht31);
+  LOG(LL_INFO, ("SHT31: temperature=%.2fC humidity=%.1f%%", temp, humid));
 
   mgos_sht31_destroy(&sht31);
   return true;
 }
 
+bool si7021(struct mgos_i2c *i2c, uint8_t i2caddr) {
+  struct mgos_si7021 *si7021;
+  float temp, humid;
+
+  if (!(si7021 = mgos_si7021_create(i2c, i2caddr))) {
+    LOG(LL_ERROR, ("Cannot create SI7021 device"));
+    return false;
+  }
+
+  temp=mgos_si7021_getTemperature(si7021);
+  humid=mgos_si7021_getHumidity(si7021);
+  LOG(LL_INFO, ("SI7021: temperature=%.2fC humidity=%.1f%%", temp, humid));
+
+  mgos_si7021_destroy(&si7021);
+  return true;
+}
+
 int main() {
   struct mgos_i2c *i2c;
 
@@ -69,7 +82,11 @@ int main() {
   }
 
   i2c_scanner(i2c);
-  sht31(i2c, 0x44);
+  for (;;) {
+    sht31(i2c, 0x44);
+    si7021(i2c, 0x44);
+    sleep(1);
+  }
 
   return 0;
 }
diff --git a/src/mgos_si7021.c b/src/mgos_si7021.c
new file mode 100644
index 0000000..fb0b7d1
--- /dev/null
+++ b/src/mgos_si7021.c
@@ -0,0 +1,77 @@
+/*
+ * Copyright 2018 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "mgos.h"
+#include "mgos_si7021_internal.h"
+#include "mgos_i2c.h"
+
+// Private functions follow
+// Private functions end
+
+// Public functions follow
+struct mgos_si7021 *mgos_si7021_create(struct mgos_i2c *i2c, uint8_t i2caddr) {
+  struct mgos_si7021 *sensor;
+
+  if (!i2c) return NULL;
+
+  sensor=calloc(1, sizeof(struct mgos_si7021));
+  if (!sensor) return NULL;
+  sensor->i2caddr=i2caddr;
+  sensor->i2c=i2c;
+  sensor->last_read_time=0;
+  return sensor;
+}
+
+void mgos_si7021_destroy(struct mgos_si7021 **sensor) {
+  if (!*sensor) return;
+  free (*sensor);
+  *sensor=NULL;
+  return;
+}
+
+bool mgos_si7021_read(struct mgos_si7021 *sensor) {
+  double now = mg_time();
+
+  if (!sensor || !sensor->i2c)
+    return false;
+
+  if (now - sensor->last_read_time < MGOS_SI7021_READ_DELAY) {
+    return true;
+  }
+  // Read out sensor data here 
+  //
+
+  LOG(LL_DEBUG, ("temperature=%.2fC humidity=%.1f%%", sensor->temperature, sensor->humidity));
+  sensor->last_read_time=now;
+  return true;
+}
+
+float mgos_si7021_getTemperature(struct mgos_si7021 *sensor) {
+  if (!mgos_si7021_read(sensor)) return NAN;
+
+  return sensor->temperature;
+}
+
+float mgos_si7021_getHumidity(struct mgos_si7021 *sensor) {
+  if (!mgos_si7021_read(sensor)) return NAN;
+
+  return sensor->humidity;
+}
+
+bool mgos_si7021_i2c_init(void) {
+  return true;
+}
+// Public functions end
diff --git a/src/mgos_si7021_internal.h b/src/mgos_si7021_internal.h
new file mode 100644
index 0000000..7518f2d
--- /dev/null
+++ b/src/mgos_si7021_internal.h
@@ -0,0 +1,38 @@
+#pragma once
+
+#include "mgos.h"
+#include "mgos_i2c.h"
+#include "mgos_si7021.h"
+#include <math.h>
+
+#define MGOS_SI7021_DEFAULT_I2CADDR       (0x40)
+
+#define MGOS_SI7021_MEASRH_HOLD_CMD       (0xE5)
+#define MGOS_SI7021_MEASRH_NOHOLD_CMD     (0xF5)
+#define MGOS_SI7021_MEASTEMP_HOLD_CMD     (0xE3)
+#define MGOS_SI7021_MEASTEMP_NOHOLD_CMD   (0xF3)
+#define MGOS_SI7021_READPREVTEMP_CMD      (0xE0)
+#define MGOS_SI7021_RESET_CMD             (0xFE)
+#define MGOS_SI7021_WRITERHT_REG_CMD      (0xE6)
+#define MGOS_SI7021_READRHT_REG_CMD       (0xE7)
+#define MGOS_SI7021_WRITEHEATER_REG_CMD   (0x51)
+#define MGOS_SI7021_READHEATER_REG_CMD    (0x11)
+#define MGOS_SI7021_ID1_CMD               (0xFA0F)
+#define MGOS_SI7021_ID2_CMD               (0xFCC9)
+#define MGOS_SI7021_FIRMVERS_CMD          (0x84B8)
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct mgos_si7021 {
+  struct mgos_i2c *i2c;
+  uint8_t i2caddr;
+  double last_read_time;
+
+  float humidity, temperature;
+};
+
+#ifdef __cplusplus
+}
+#endif