diff --git a/Tutorial 42 - LCD16x2 I2C/lcd16x2_i2c.h b/Tutorial 42 - LCD16x2 I2C/lcd16x2_i2c.h
index 39996b1..26d19c0 100644
--- a/Tutorial 42 - LCD16x2 I2C/lcd16x2_i2c.h	
+++ b/Tutorial 42 - LCD16x2 I2C/lcd16x2_i2c.h	
@@ -2,6 +2,7 @@
  * lcd16x2_i2c.h
  *
  *  Created on: Mar 28, 2020
+ *   modified on : April 4 2022 by Zorrovicky
  *      Author: Mohamed Yaqoob
  */
 
@@ -50,7 +51,7 @@ void lcd16x2_i2c_cursorShow(bool state);
 void lcd16x2_i2c_clear(void);
 
 /**
- * @brief Display ON/OFF, to hide all characters, but not cl/*
+ * @brief Display ON/OFF, to hide all characters, but not clear
  * lcd16x2_i2c.c
  *
  *  Created on: Mar 28, 2020
@@ -96,216 +97,83 @@ void lcd16x2_i2c_clear(void);
 
 /* Library variables */
 static I2C_HandleTypeDef* lcd16x2_i2cHandle;
-static uint8_t LCD_I2C_SLAVE_ADDRESS=0;
+//static uint8_t LCD_I2C_SLAVE_ADDRESS=0;
 #define LCD_I2C_SLAVE_ADDRESS_0  0x4E
-#define LCD_I2C_SLAVE_ADDRESS_1  0x7E
+#define LCD_I2C_SLAVE_ADDRESS_1  0x27
 
 /* Private functions */
-static void lcd16x2_i2c_sendCommand(uint8_t command)
-{
-  const uint8_t command_0_3 = (0xF0 & (command<<4));
-  const uint8_t command_4_7 = (0xF0 & command);
-  uint8_t i2cData[4] =
-  {
-      command_4_7 | LCD_EN | LCD_BK_LIGHT,
-      command_4_7 | LCD_BK_LIGHT,
-      command_0_3 | LCD_EN | LCD_BK_LIGHT,
-      command_0_3 | LCD_BK_LIGHT,
-  };
-  HAL_I2C_Master_Transmit(lcd16x2_i2cHandle, LCD_I2C_SLAVE_ADDRESS, i2cData, 4, 200);
-}
-
-static void lcd16x2_i2c_sendData(uint8_t data)
-{
-  const uint8_t data_0_3 = (0xF0 & (data<<4));
-  const uint8_t data_4_7 = (0xF0 & data);
-  uint8_t i2cData[4] =
-  {
-      data_4_7 | LCD_EN | LCD_BK_LIGHT | LCD_RS,
-      data_4_7 | LCD_BK_LIGHT | LCD_RS,
-      data_0_3 | LCD_EN | LCD_BK_LIGHT | LCD_RS,
-      data_0_3 | LCD_BK_LIGHT | LCD_RS,
-  };
-  HAL_I2C_Master_Transmit(lcd16x2_i2cHandle, LCD_I2C_SLAVE_ADDRESS, i2cData, 4, 200);
-}
+static void lcd16x2_i2c_sendCommand(uint8_t command);
+
+
+static void lcd16x2_i2c_sendData(uint8_t data);
+
 
 
 /**
  * @brief Initialise LCD16x2
  * @param[in] *pI2cHandle - pointer to HAL I2C handle
  */
-bool lcd16x2_i2c_init(I2C_HandleTypeDef *pI2cHandle)
-{
-  HAL_Delay(50);
-  lcd16x2_i2cHandle = pI2cHandle;
-  if(HAL_I2C_IsDeviceReady(lcd16x2_i2cHandle, LCD_I2C_SLAVE_ADDRESS_0, 5, 500) != HAL_OK)
-  {
-    if(HAL_I2C_IsDeviceReady(lcd16x2_i2cHandle, LCD_I2C_SLAVE_ADDRESS_1, 5, 500) != HAL_OK)
-    {
-      return false;
-    }
-    else
-    {
-      LCD_I2C_SLAVE_ADDRESS = LCD_I2C_SLAVE_ADDRESS_1;
-    }
-  }
-  else
-  {
-    LCD_I2C_SLAVE_ADDRESS = LCD_I2C_SLAVE_ADDRESS_0;
-  }
-  //Initialise LCD for 4-bit operation
-  //1. Wait at least 15ms
-  HAL_Delay(45);
-  //2. Attentions sequence
-  lcd16x2_i2c_sendCommand(0x30);
-  HAL_Delay(5);
-  lcd16x2_i2c_sendCommand(0x30);
-  HAL_Delay(1);
-  lcd16x2_i2c_sendCommand(0x30);
-  HAL_Delay(8);
-  lcd16x2_i2c_sendCommand(0x20);
-  HAL_Delay(8);
-
-  lcd16x2_i2c_sendCommand(LCD_FUNCTIONSET | LCD_FUNCTION_N);
-  HAL_Delay(1);
-  lcd16x2_i2c_sendCommand(LCD_DISPLAYCONTROL);
-  HAL_Delay(1);
-  lcd16x2_i2c_sendCommand(LCD_CLEARDISPLAY);
-  HAL_Delay(3);
-  lcd16x2_i2c_sendCommand(0x04 | LCD_ENTRY_ID);
-  HAL_Delay(1);
-  lcd16x2_i2c_sendCommand(LCD_DISPLAYCONTROL | LCD_DISPLAY_D);
-  HAL_Delay(3);
-
-  return true;
-}
+bool lcd16x2_i2c_init(I2C_HandleTypeDef *pI2cHandle);
+
 
 /**
  * @brief Set cursor position
  * @param[in] row - 0 or 1 for line1 or line2
  * @param[in] col - 0 - 15 (16 columns LCD)
  */
-void lcd16x2_i2c_setCursor(uint8_t row, uint8_t col)
-{
-  uint8_t maskData;
-  maskData = (col)&0x0F;
-  if(row==0)
-  {
-    maskData |= (0x80);
-    lcd16x2_i2c_sendCommand(maskData);
-  }
-  else
-  {
-    maskData |= (0xc0);
-    lcd16x2_i2c_sendCommand(maskData);
-  }
-}
+void lcd16x2_i2c_setCursor(uint8_t row, uint8_t col);
 
 /**
  * @brief Move to beginning of 1st line
  */
-void lcd16x2_i2c_1stLine(void)
-{
-  lcd16x2_i2c_setCursor(0,0);
-}
+void lcd16x2_i2c_1stLine(void);
+
 /**
  * @brief Move to beginning of 2nd line
  */
-void lcd16x2_i2c_2ndLine(void)
-{
-  lcd16x2_i2c_setCursor(1,0);
-}
+void lcd16x2_i2c_2ndLine(void);
 
 /**
  * @brief Select LCD Number of lines mode
  */
-void lcd16x2_i2c_TwoLines(void)
-{
-  lcd16x2_i2c_sendCommand(LCD_FUNCTIONSET | LCD_FUNCTION_N);
-}
-void lcd16x2_i2c_OneLine(void)
-{
-  lcd16x2_i2c_sendCommand(LCD_FUNCTIONSET);
-}
+void lcd16x2_i2c_TwoLines(void);
+
+void lcd16x2_i2c_OneLine(void);
 
 /**
  * @brief Cursor ON/OFF
  */
-void lcd16x2_i2c_cursorShow(bool state)
-{
-  if(state)
-  {
-    lcd16x2_i2c_sendCommand(LCD_DISPLAYCONTROL | LCD_DISPLAY_B | LCD_DISPLAY_C | LCD_DISPLAY_D);
-  }
-  else
-  {
-    lcd16x2_i2c_sendCommand(LCD_DISPLAYCONTROL | LCD_DISPLAY_D);
-  }
-}
+void lcd16x2_i2c_cursorShow(bool state);
 
 /**
  * @brief Display clear
  */
-void lcd16x2_i2c_clear(void)
-{
-  lcd16x2_i2c_sendCommand(LCD_CLEARDISPLAY);
-  HAL_Delay(3);
-}
+void lcd16x2_i2c_clear(void);
+
 
 /**
  * @brief Display ON/OFF, to hide all characters, but not clear
  */
-void lcd16x2_i2c_display(bool state)
-{
-  if(state)
-  {
-    lcd16x2_i2c_sendCommand(LCD_DISPLAYCONTROL | LCD_DISPLAY_B | LCD_DISPLAY_C | LCD_DISPLAY_D);
-  }
-  else
-  {
-    lcd16x2_i2c_sendCommand(LCD_DISPLAYCONTROL | LCD_DISPLAY_B | LCD_DISPLAY_C);
-  }
-}
+void lcd16x2_i2c_display(bool state);
+
 
 /**
  * @brief Shift content to right
  */
-void lcd16x2_i2c_shiftRight(uint8_t offset)
-{
-  for(uint8_t i=0; i<offset;i++)
-  {
-    lcd16x2_i2c_sendCommand(0x1c);
-  }
-}
+void lcd16x2_i2c_shiftRight(uint8_t offset);
 
 /**
  * @brief Shift content to left
  */
-void lcd16x2_i2c_shiftLeft(uint8_t offset)
-{
-  for(uint8_t i=0; i<offset;i++)
-  {
-    lcd16x2_i2c_sendCommand(0x18);
-  }
-}
+void lcd16x2_i2c_shiftLeft(uint8_t offset);
+
 
 /**
  * @brief Print to display
  */
-void lcd16x2_i2c_printf(const char* str, ...)
-{
-  char stringArray[20];
-  va_list args;
-  va_start(args, str);
-  vsprintf(stringArray, str, args);
-  va_end(args);
-  for(uint8_t i=0;  i<strlen(stringArray) && i<16; i++)
-  {
-    lcd16x2_i2c_sendData((uint8_t)stringArray[i]);
-  }
-}
-ear
- */
+void lcd16x2_i2c_printf(const char* str, ...);
+
+
 void lcd16x2_i2c_display(bool state);
 
 /**