diff --git a/Core/Inc/external_temp.h b/Core/Inc/external_temp.h
new file mode 100644
index 0000000..3ee5e6e
--- /dev/null
+++ b/Core/Inc/external_temp.h
@@ -0,0 +1,11 @@
+#ifndef __EXTERNAL_TEMP
+#define __EXTERNAL_TEMP
+
+extern ADC_HandleTypeDef hadc1;
+
+
+
+void external_temp_show_celsius(void);
+void external_temp_show_fahrenheit(void);
+
+#endif
diff --git a/Core/Inc/generic_macros.h b/Core/Inc/generic_macros.h
new file mode 100644
index 0000000..b864600
--- /dev/null
+++ b/Core/Inc/generic_macros.h
@@ -0,0 +1,10 @@
+#ifndef __GENERIC_MACROS
+#define __GENERIC_MACROS
+
+#define PANIC(status)        \
+	do {                     \
+		GPIOD->ODR = status; \
+		while (1) {}         \
+	} while (0)
+
+#endif
diff --git a/Core/Inc/lcd.h b/Core/Inc/lcd.h
new file mode 100644
index 0000000..1082aca
--- /dev/null
+++ b/Core/Inc/lcd.h
@@ -0,0 +1,24 @@
+#ifndef __LCD
+#define __LCD
+
+#define DISPLAY_RS  ((uint16_t) (0x1U << 7))
+#define DISPLAY_RW  ((uint16_t) (0x1U << 10))
+#define DISPLAY_ENA ((uint16_t) (0x1U << 11))
+
+#define DISPLAY_POLL_UNTIL_READY do { while (display_read_status() & 0x80) {} } while (0)
+
+#define DISPLAY_SET_INCREMENT do { display_write_instruction_byte(0x06); } while (0)
+#define DISPLAY_SET_DECREMENT do { display_write_instruction_byte(0x04); } while (0)
+
+#define DISPLAY_SET_CURSOR(line, position) do { display_write_instruction_byte(0x80 | (line << 6) | position); } while (0)
+
+#define DISPLAY_CLEAR do { display_write_instruction_byte(0x01); } while (0)
+
+
+void display_init(void);
+uint8_t display_read_status(void);
+void display_write_instruction_byte(uint8_t code);
+void display_write_data_byte(uint8_t code);
+void display_write_data_seq(char *codes);
+
+#endif
diff --git a/Core/Src/external-temperature.c b/Core/Src/external-temperature.c
new file mode 100644
index 0000000..e69de29
diff --git a/Core/Src/external_temp.c b/Core/Src/external_temp.c
new file mode 100644
index 0000000..e9cc7c1
--- /dev/null
+++ b/Core/Src/external_temp.c
@@ -0,0 +1,98 @@
+#include "main.h"
+#include "generic_macros.h"
+#include "lcd.h"
+#include "external_temp.h"
+
+static uint32_t external_temp_read(void)
+{
+	HAL_ADC_Start(&hadc1);
+	if (HAL_ADC_PollForConversion(&hadc1, 100) != HAL_OK)
+		PANIC(0x4000);
+
+	return HAL_ADC_GetValue(&hadc1);
+}
+
+static int external_temp_convert_to_celsius(uint32_t value)
+{
+	return (2512 - value) << 2;
+}
+
+static int external_temp_convert_to_fahrenheit(uint32_t value)
+{
+	return (2953 - value) * 50 / 7;
+}
+
+static void external_temp_print(int temperature)
+{
+	int add_sign = temperature < 0;
+	if (add_sign)
+		temperature = ~(temperature - 1); // if value is not positive, the string conversion will break
+
+	int temp1 = temperature;
+
+	for (int i = 0; i < 2; i++) {
+		temperature /= 10;
+		display_write_data_byte('0' + (char) (temp1 - temperature * 10));
+		temp1 = temperature;
+	}
+
+	display_write_data_byte('.');
+
+	for (int i = 0; i < 3; i++) {
+		temperature /= 10;
+		display_write_data_byte('0' + (char) (temp1 - temperature * 10));
+		temp1 = temperature;
+
+		if (temp1 == 0) {
+			display_write_data_seq("  ");
+			break;
+		}
+	}
+
+	if (add_sign) {
+		DISPLAY_SET_CURSOR(1, 0);
+		display_write_data_byte('-');
+	}
+}
+
+static void external_temp_print_celsius(int temperature)
+{
+	DISPLAY_SET_CURSOR(1, 7);
+	DISPLAY_SET_DECREMENT;
+	display_write_data_seq("C ");
+
+	external_temp_print(temperature);
+}
+
+static void external_temp_print_fahrenheit(int temperature)
+{
+	DISPLAY_SET_CURSOR(1, 7);
+	DISPLAY_SET_DECREMENT;
+	display_write_data_seq("F ");
+
+	external_temp_print(temperature);
+}
+
+void external_temp_show_celsius(void)
+{
+	DISPLAY_CLEAR;
+	DISPLAY_SET_INCREMENT;
+
+	display_write_data_seq("Temperature");
+
+	uint32_t value = external_temp_read();
+	int temp = external_temp_convert_to_celsius(value);
+	external_temp_print_celsius(temp);
+}
+
+void external_temp_show_fahrenheit(void)
+{
+	DISPLAY_CLEAR;
+	DISPLAY_SET_INCREMENT;
+
+	display_write_data_seq("Temperature");
+
+	uint32_t value = external_temp_read();
+	int temp = external_temp_convert_to_fahrenheit(value);
+	external_temp_print_fahrenheit(temp);
+}
diff --git a/Core/Src/lcd.c b/Core/Src/lcd.c
new file mode 100644
index 0000000..3aebda7
--- /dev/null
+++ b/Core/Src/lcd.c
@@ -0,0 +1,92 @@
+#include "main.h"
+#include "lcd.h"
+#include "generic_macros.h"
+
+void display_init(void)
+{
+	// switch to 4-bit 2-line mode
+	  display_write_instruction_byte(0x28);
+
+	  // clear display
+	  display_write_instruction_byte(0x01);
+
+	  // enable display
+	  display_write_instruction_byte(0x0C);
+
+	  // move cursor to first line
+	  display_write_instruction_byte(0x80);
+}
+
+uint8_t display_read_status(void)
+{
+	// make sure GPIOE is in correct mode
+	GPIOE->MODER = 0x00504000;
+
+	if (GPIOE->MODER != 0x00504000)
+		PANIC(0x4000);
+
+	uint8_t status = 0;
+
+	GPIOE->ODR = 0x0;
+	GPIOE->BSRR = DISPLAY_RW;
+
+	GPIOE->BSRR = DISPLAY_ENA;
+	status |= (GPIOE->IDR & 0xF000) >> 8;
+	GPIOE->BSRR = (DISPLAY_ENA << 16);
+
+	GPIOE->BSRR = DISPLAY_ENA;
+	status |= (GPIOE->IDR & 0xF000) >> 12;
+	GPIOE->BSRR = (DISPLAY_ENA << 16);
+
+	GPIOE->ODR = 0x0;
+
+	return status;
+}
+
+void display_write_instruction_byte(uint8_t code)
+{
+	DISPLAY_POLL_UNTIL_READY;
+
+	// make sure GPIOE is in correct mode
+	GPIOE->MODER = 0x55504000;
+
+	if (GPIOE->MODER != 0x55504000)
+		PANIC(0x4000);
+
+	GPIOE->ODR = (code & 0xF0) << 8;
+	GPIOE->BSRR = DISPLAY_ENA;
+	GPIOE->BSRR = (DISPLAY_ENA << 16);
+
+	GPIOE->ODR = (code & 0x0F) << 12;
+	GPIOE->BSRR = DISPLAY_ENA;
+	GPIOE->BSRR = (DISPLAY_ENA << 16);
+}
+
+void display_write_data_byte(uint8_t code)
+{
+	DISPLAY_POLL_UNTIL_READY;
+
+	// make sure GPIOE is in correct mode
+	GPIOE->MODER = 0x55504000;
+
+	if (GPIOE->MODER != 0x55504000)
+		PANIC(0x4000);
+
+	GPIOE->ODR = ((code & 0xF0) << 8) | (DISPLAY_RS);
+	GPIOE->BSRR = DISPLAY_ENA;
+	GPIOE->BSRR = DISPLAY_ENA << 16;
+
+	GPIOE->ODR = ((code & 0x0F) << 12) | (DISPLAY_RS);
+	GPIOE->BSRR = DISPLAY_ENA;
+	GPIOE->BSRR = DISPLAY_ENA << 16;
+}
+
+void display_write_data_seq(char *codes)
+{
+	for (size_t i = 0; i < 16; i++) {
+		if (codes[i] != 0)
+			display_write_data_byte(codes[i]);
+		else
+			break;
+	}
+}
diff --git a/Core/Src/main.c b/Core/Src/main.c
index 1162e63..9aaa192 100644
--- a/Core/Src/main.c
+++ b/Core/Src/main.c
@@ -22,6 +22,10 @@
 /* Private includes ----------------------------------------------------------*/
 /* USER CODE BEGIN Includes */
 
+#include "generic_macros.h"
+#include "lcd.h"
+#include "external_temp.h"
+
 /* USER CODE END Includes */
 
 /* Private typedef -----------------------------------------------------------*/
@@ -32,18 +36,6 @@
 /* Private define ------------------------------------------------------------*/
 /* USER CODE BEGIN PD */
 
-#define DISPLAY_RS  ((uint16_t) (0x1U << 7))
-#define DISPLAY_RW  ((uint16_t) (0x1U << 10))
-#define DISPLAY_ENA ((uint16_t) (0x1U << 11))
-
-#define PANIC(status)        \
-	do {                     \
-		GPIOD->ODR = status; \
-		while (1) {}         \
-	} while (0)
-
-#define POLL_UNTIL_READY do { while (read_status() & 0x80) {} } while (0)
-
 /* USER CODE END PD */
 
 /* Private macro -------------------------------------------------------------*/
@@ -52,16 +44,23 @@
 /* USER CODE END PM */
 
 /* Private variables ---------------------------------------------------------*/
+ADC_HandleTypeDef hadc1;
 
 /* USER CODE BEGIN PV */
 
-int change = 1;
+void ((*executors[])(void)) = {
+		external_temp_show_celsius,
+		external_temp_show_fahrenheit
+};
+
+int current_executor_id = 0;
 
 /* USER CODE END PV */
 
 /* Private function prototypes -----------------------------------------------*/
 void SystemClock_Config(void);
 static void MX_GPIO_Init(void);
+static void MX_ADC1_Init(void);
 /* USER CODE BEGIN PFP */
 
 /* USER CODE END PFP */
@@ -69,70 +68,6 @@ static void MX_GPIO_Init(void);
 /* Private user code ---------------------------------------------------------*/
 /* USER CODE BEGIN 0 */
 
-uint8_t read_status(void)
-{
-	// make sure GPIOE is in correct mode
-	GPIOE->MODER = 0x00504000;
-
-	if (GPIOE->MODER != 0x00504000)
-		PANIC(0x4000);
-
-	uint8_t status = 0;
-
-	GPIOE->ODR = 0x0;
-	GPIOE->BSRR = DISPLAY_RW;
-
-	GPIOE->BSRR = DISPLAY_ENA;
-	status |= (GPIOE->IDR & 0xF000) >> 8;
-	GPIOE->BSRR = (DISPLAY_ENA << 16);
-
-	GPIOE->BSRR = DISPLAY_ENA;
-	status |= (GPIOE->IDR & 0xF000) >> 12;
-	GPIOE->BSRR = (DISPLAY_ENA << 16);
-
-	GPIOE->ODR = 0x0;
-
-	return status;
-}
-
-void write_instruction_byte(uint8_t code)
-{
-	POLL_UNTIL_READY;
-
-	// make sure GPIOE is in correct mode
-	GPIOE->MODER = 0x55504000;
-
-	if (GPIOE->MODER != 0x55504000)
-		PANIC(0x4000);
-
-	GPIOE->ODR = (code & 0xF0) << 8;
-	GPIOE->BSRR = DISPLAY_ENA;
-	GPIOE->BSRR = (DISPLAY_ENA << 16);
-
-	GPIOE->ODR = (code & 0x0F) << 12;
-	GPIOE->BSRR = DISPLAY_ENA;
-	GPIOE->BSRR = (DISPLAY_ENA << 16);
-}
-
-void write_data_byte(uint8_t code)
-{
-	POLL_UNTIL_READY;
-
-	// make sure GPIOE is in correct mode
-	GPIOE->MODER = 0x55504000;
-
-	if (GPIOE->MODER != 0x55504000)
-		PANIC(0x4000);
-
-	GPIOE->ODR = ((code & 0xF0) << 8) | (DISPLAY_RS);
-	GPIOE->BSRR = DISPLAY_ENA;
-	GPIOE->BSRR = DISPLAY_ENA << 16;
-
-	GPIOE->ODR = ((code & 0x0F) << 12) | (DISPLAY_RS);
-	GPIOE->BSRR = DISPLAY_ENA;
-	GPIOE->BSRR = DISPLAY_ENA << 16;
-}
-
 /* USER CODE END 0 */
 
 /**
@@ -164,67 +99,21 @@ int main(void)
 
   /* Initialize all configured peripherals */
   MX_GPIO_Init();
+  MX_ADC1_Init();
   /* USER CODE BEGIN 2 */
 
   GPIOD->ODR = 0xF000;
-
-  // switch to 4-bit 2-line mode
-  write_instruction_byte(0x28);
-
-  // reset display
-  write_instruction_byte(0x01);
-
-  // enable display
-  write_instruction_byte(0x0C);
-
-  // move cursor to first line
-  write_instruction_byte(0x80);
-
-  // write string
-  char a[] = "Well, hi there!";
-  for (int i = 0; i < sizeof(a)-1; i++) {
-	  write_data_byte(a[i]);
-  }
-
-  /*
-  // move cursor to second line
-  write_instruction_byte(0xC0);
-  while (read_status() & 0x80) {}
-
-  // write another string
-  char b[] = "I'm doing it!";
-  for (int i = 0; i < sizeof(b)-1; i++) {
-	  write_data_byte(b[i]);
-	  while (read_status() & 0x80) {}
-  }
-  */
-
+  display_init();
   GPIOD->ODR = 0x0000;
 
-  unsigned int counter = 0;
-  write_instruction_byte(0x04); // set address decrement after write
-
   /* USER CODE END 2 */
 
   /* Infinite loop */
   /* USER CODE BEGIN WHILE */
   while (1)
   {
-	counter += change;
-	counter &= 0xFFFF;
-
-	unsigned int c = counter;
-
-	write_instruction_byte(0xC4);
-
-	for (int i = 0; i < 5; i++) {
-		int current_digit = c % 10;
-		c /= 10;
-
-		write_data_byte('0' + (char) current_digit);
-	}
-
-	HAL_Delay(10);
+	executors[current_executor_id]();
+	HAL_Delay(250);
     /* USER CODE END WHILE */
 
     /* USER CODE BEGIN 3 */
@@ -273,6 +162,58 @@ void SystemClock_Config(void)
   }
 }
 
+/**
+  * @brief ADC1 Initialization Function
+  * @param None
+  * @retval None
+  */
+static void MX_ADC1_Init(void)
+{
+
+  /* USER CODE BEGIN ADC1_Init 0 */
+
+  /* USER CODE END ADC1_Init 0 */
+
+  ADC_ChannelConfTypeDef sConfig = {0};
+
+  /* USER CODE BEGIN ADC1_Init 1 */
+
+  /* USER CODE END ADC1_Init 1 */
+
+  /** Configure the global features of the ADC (Clock, Resolution, Data Alignment and number of conversion)
+  */
+  hadc1.Instance = ADC1;
+  hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV2;
+  hadc1.Init.Resolution = ADC_RESOLUTION_12B;
+  hadc1.Init.ScanConvMode = DISABLE;
+  hadc1.Init.ContinuousConvMode = DISABLE;
+  hadc1.Init.DiscontinuousConvMode = DISABLE;
+  hadc1.Init.ExternalTrigConvEdge = ADC_EXTERNALTRIGCONVEDGE_NONE;
+  hadc1.Init.ExternalTrigConv = ADC_SOFTWARE_START;
+  hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;
+  hadc1.Init.NbrOfConversion = 1;
+  hadc1.Init.DMAContinuousRequests = DISABLE;
+  hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;
+  if (HAL_ADC_Init(&hadc1) != HAL_OK)
+  {
+    Error_Handler();
+  }
+
+  /** Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time.
+  */
+  sConfig.Channel = ADC_CHANNEL_9;
+  sConfig.Rank = 1;
+  sConfig.SamplingTime = ADC_SAMPLETIME_480CYCLES;
+  if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)
+  {
+    Error_Handler();
+  }
+  /* USER CODE BEGIN ADC1_Init 2 */
+
+  /* USER CODE END ADC1_Init 2 */
+
+}
+
 /**
   * @brief GPIO Initialization Function
   * @param None
@@ -286,6 +227,7 @@ static void MX_GPIO_Init(void)
 
   /* GPIO Ports Clock Enable */
   __HAL_RCC_GPIOA_CLK_ENABLE();
+  __HAL_RCC_GPIOB_CLK_ENABLE();
   __HAL_RCC_GPIOE_CLK_ENABLE();
   __HAL_RCC_GPIOD_CLK_ENABLE();
 
diff --git a/Core/Src/stm32f4xx_it.c b/Core/Src/stm32f4xx_it.c
index 106db94..3f23040 100644
--- a/Core/Src/stm32f4xx_it.c
+++ b/Core/Src/stm32f4xx_it.c
@@ -41,7 +41,9 @@
 
 /* Private variables ---------------------------------------------------------*/
 /* USER CODE BEGIN PV */
-extern int change;
+extern void ((*executors[])(void));
+extern void *current_executor(void);
+extern int current_executor_id;
 /* USER CODE END PV */
 
 /* Private function prototypes -----------------------------------------------*/
@@ -205,9 +207,15 @@ void EXTI0_IRQHandler(void)
 {
   /* USER CODE BEGIN EXTI0_IRQn 0 */
 
-  change *= -1;
+	GPIOD->ODR = 0x1000;
+
+	current_executor_id += 1;
+	current_executor_id &= 1;
+
+	for (int i = 900000; i > 0; i--) asm("nop");
+
+	GPIOD->ODR = 0x0000;
 
-  for (int i = 0; i < 400000; i++) {asm("nop");}
   /* USER CODE END EXTI0_IRQn 0 */
   HAL_GPIO_EXTI_IRQHandler(GPIO_PIN_0);
   /* USER CODE BEGIN EXTI0_IRQn 1 */