diff --git a/fw/Core/Inc/main.h b/fw/Core/Inc/main.h
index 4720b03..94b7091 100644
--- a/fw/Core/Inc/main.h
+++ b/fw/Core/Inc/main.h
@@ -49,6 +49,7 @@ extern "C" {
 /* Private includes ----------------------------------------------------------*/
 /* USER CODE BEGIN Includes */
 #include "led.h"
+#include "sht4x.h"
 /* USER CODE END Includes */
 
 /* Exported types ------------------------------------------------------------*/
diff --git a/fw/Core/Inc/sht4x.h b/fw/Core/Inc/sht4x.h
new file mode 100644
index 0000000..a73fd2c
--- /dev/null
+++ b/fw/Core/Inc/sht4x.h
@@ -0,0 +1,51 @@
+/*
+ * sht4x.h
+ *
+ *  Created on: Jun 8, 2021
+ *      Author: user
+ */
+
+#ifndef INC_SHT4X_H_
+#define INC_SHT4X_H_
+
+#include "stdint.h"
+#include "stm32l0xx_ll_i2c.h"
+
+/*
+ * Defines & macros
+ */
+
+#define SHT4X_I2C_ADDRESS 0x44
+
+/*
+ * Data types
+ */
+
+typedef struct {
+	I2C_TypeDef *i2c;
+} sht4x_context_t;
+
+typedef enum {
+	START_MEAS_HIGH_PRECISION = 0xFD,
+	START_MEAS_MEDIUM_PRECISION = 0xF6,
+	START_MEAS_LOW_PRECISION = 0xE0,
+	READ_SERIAL = 0x89,
+	SOFT_RESET = 0x94,
+	HEATER_200_mW_1_s = 0x39,
+	HEATER_200_mW_01_s = 0x32,
+	HEATER_110_mW_1_s = 0x2F,
+	HEATER_110_mW_01_s = 0x24,
+	HEATER_20_mW_1_s = 0x1E,
+	HEATER_20_mW_01_s = 0x15
+} sht4x_cmd_t;
+
+/*
+ * Function prototypes
+ */
+
+int sht4x_init(sht4x_context_t *context);
+int sht4x_send_cmd(sht4x_cmd_t cmd);
+int sht4x_read_data(uint8_t *buffer, int len);
+int sht4x_measure(int *temperature, int *relative_humidity);
+
+#endif /* INC_SHT4X_H_ */
diff --git a/fw/Core/Src/main.c b/fw/Core/Src/main.c
index 879628a..9227917 100644
--- a/fw/Core/Src/main.c
+++ b/fw/Core/Src/main.c
@@ -108,14 +108,20 @@ int main(void)
   led_context.blue_led_pin = LED_B_Pin;
   led_init(&led_context, 50, 1000);
   led_set_color(80, 0, 0);
+  /* SHT4x context init */
+  sht4x_context_t sht4x_context;
+  sht4x_context.i2c = I2C1;
+  sht4x_init(&sht4x_context);
   /* USER CODE END 2 */
 
   /* Infinite loop */
   /* USER CODE BEGIN WHILE */
+  int T, RH;
+  sht4x_measure(&T, &RH);
   while (1)
   {
-    /* USER CODE END WHILE */
 	led_pwm_handler(); // TODO temporary, should be placed in timer interrupt (SysTick)
+    /* USER CODE END WHILE */
     /* USER CODE BEGIN 3 */
   }
   /* USER CODE END 3 */
@@ -218,7 +224,6 @@ static void MX_I2C1_Init(void)
   LL_I2C_Init(I2C1, &I2C_InitStruct);
   LL_I2C_SetOwnAddress2(I2C1, 0, LL_I2C_OWNADDRESS2_NOMASK);
   /* USER CODE BEGIN I2C1_Init 2 */
-
   /* USER CODE END I2C1_Init 2 */
 
 }
diff --git a/fw/Core/Src/sht4x.c b/fw/Core/Src/sht4x.c
new file mode 100644
index 0000000..d6dd018
--- /dev/null
+++ b/fw/Core/Src/sht4x.c
@@ -0,0 +1,83 @@
+/*
+ * sht4x.c
+ *
+ *  Created on: Jun 8, 2021
+ *      Author: user
+ */
+
+#include "sht4x.h"
+
+sht4x_context_t *sht4x_context;
+
+int sht4x_init(sht4x_context_t *context)
+{
+	sht4x_context = context;
+}
+
+void i2c_transmit(uint8_t address, uint8_t *buffer, int len)
+{
+	LL_I2C_HandleTransfer(sht4x_context->i2c, address, LL_I2C_ADDRESSING_MODE_7BIT, len,
+			LL_I2C_MODE_AUTOEND, LL_I2C_GENERATE_START_WRITE);
+	int i = 0;
+	while (!LL_I2C_IsActiveFlag_STOP(sht4x_context->i2c)) {
+		if (LL_I2C_IsActiveFlag_TXE(sht4x_context->i2c)) {
+			if (i < len) {
+				LL_I2C_TransmitData8(sht4x_context->i2c, buffer[i++]);
+			}
+		}
+	}
+	LL_I2C_ClearFlag_STOP(sht4x_context->i2c);
+}
+
+void i2c_receive(uint8_t address, uint8_t *buffer, int len)
+{
+	LL_I2C_HandleTransfer(sht4x_context->i2c, address, LL_I2C_ADDRESSING_MODE_7BIT, len,
+				LL_I2C_MODE_AUTOEND, LL_I2C_GENERATE_START_READ);
+	int i = 0;
+	while (!LL_I2C_IsActiveFlag_STOP(sht4x_context->i2c)) {
+		if (LL_I2C_IsActiveFlag_RXNE(sht4x_context->i2c)) {
+			if (i < len) {
+				buffer[i++] = LL_I2C_ReceiveData8(sht4x_context->i2c);
+			}
+		}
+	}
+	LL_I2C_ClearFlag_STOP(sht4x_context->i2c);
+}
+
+int sht4x_send_cmd(sht4x_cmd_t cmd)
+{
+
+}
+
+int sht4x_read_data(uint8_t *buffer, int len)
+{
+
+}
+
+int sht4x_measure(int *temperature, int *relative_humidity)
+{
+	uint8_t buffer[32];
+
+	// start measurement
+	buffer[0] = START_MEAS_HIGH_PRECISION;
+	i2c_transmit(SHT4X_I2C_ADDRESS, buffer, 1);
+	// delay TODO
+	volatile int j,k;
+	for (j = 0; j < 100000; j++);
+	// read out
+	i2c_receive(SHT4X_I2C_ADDRESS, buffer, 6);
+	// TODO
+
+	uint32_t t_ticks = (buffer[0] << 8) + buffer[1];
+	uint32_t rh_ticks = (buffer[3] << 8) + buffer[4];
+	int t_degC = -45 + 175 * t_ticks / 65535;
+	int rh_pRH = -6 + 125 * rh_ticks / 65535;
+	if (rh_pRH > 100) {
+			rh_pRH = 100;
+	}
+	if (rh_pRH < 0) {
+		rh_pRH = 0;
+	}
+	*temperature = t_degC;
+	*relative_humidity = rh_pRH;
+}