text: /**
    ******************************************************************************
    * @file    Examples_LL/I2C/I2C_OneBoard_Communication_IT_Init/Src/main.c
    * @author  MCD Application Team
    * @brief   This example describes how to send/receive bytes over I2C IP using
    *          the STM32F7xx I2C LL API.
    *          Peripheral initialization done using LL initialization function.
    ******************************************************************************
    * @attention
    *
    * Copyright (c) 2016 STMicroelectronics.
    * All rights reserved.
    *
    * This software is licensed under terms that can be found in the LICENSE file
    * in the root directory of this software component.
    * If no LICENSE file comes with this software, it is provided AS-IS.
    *
    ******************************************************************************
    */
  
  /* Includes ------------------------------------------------------------------*/
  #include "main.h"
  
  /** @addtogroup STM32F7xx_LL_Examples
    * @{
    */
  
  /** @addtogroup I2C_OneBoard_Communication_IT_Init
    * @{
    */
  
  /* Private typedef -----------------------------------------------------------*/
  LL_I2C_InitTypeDef i2c_initstruct;
  
  /* Private define ------------------------------------------------------------*/
  /**
    * @brief I2C devices settings
    */
  /* Timing register value is computed with the STM32CubeMX Tool,
    * Fast Mode @400kHz with I2CCLK = 216 MHz,
    * rise time = 100ns, fall time = 20ns
    * Timing Value = (uint32_t)0x00A01E5D
    */
  #define I2C_TIMING               0x00A01E5D
  
  /**
    * @brief Define related to SlaveTransmit process
    */
  #define SLAVE_BYTE_TO_SEND       (uint8_t)0xA5
  
  /* Private macro -------------------------------------------------------------*/
  
  /* Private variables ---------------------------------------------------------*/
  __IO uint8_t ubButtonPress       = 0;
  
  /**
    * @brief Variables related to MasterReceive process
    */
  uint8_t      aReceiveBuffer[0xF] = {0};
  __IO uint8_t ubReceiveIndex      = 0;
  
  /* Private function prototypes -----------------------------------------------*/
  void     SystemClock_Config(void);
  void     Configure_I2C_Slave(void);
  void     Configure_I2C_Master(void);
  void     LED_Init(void);
  void     LED_On(void);
  void     LED_Off(void);
  void     LED_Blinking(uint32_t Period);
  void     WaitForUserButtonPress(void);
  void     Handle_I2C_Master(void);
  void     UserButton_Init(void);
  static void CPU_CACHE_Enable(void);
  
  /* Private functions ---------------------------------------------------------*/
  
  /**
    * @brief  Main program
    * @param  None
    * @retval None
    */
  int main(void)
  {
    /* Enable the CPU Cache */
    CPU_CACHE_Enable();
  
    /* Configure the system clock to 216 MHz */
    SystemClock_Config();
  
    /* Initialize LED1 */
    LED_Init();
  
    /* Set LED1 Off */
    LED_Off();
  
    /* Initialize User push-button in EXTI mode */
    UserButton_Init();
  
    /* Configure I2C2 (I2C IP configuration in Slave mode and related GPIO initialization) */
    Configure_I2C_Slave();
  
    /* Configure I2C1 (I2C IP configuration in Master mode and related GPIO initialization) */
    Configure_I2C_Master();
  
    /* Wait for User push-button press to start transfer */
    WaitForUserButtonPress();
  
    /* Handle I2C1 events (Master) */
    Handle_I2C_Master();
  
    /* Infinite loop */
    while (1)
    {
    }
  }
  
  /**
    * @brief  This function configures I2C2 in Slave mode.
    * @note   This function is used to :
    *         -1- Enables GPIO clock and configures the I2C2 pins.
    *         -2- Enable the I2C2 peripheral clock and I2C2 clock source.
    *         -3- Configure NVIC for I2C2.
    *         -4- Configure and Enable I2C2 functional parameters.
    *         -5- Enable I2C2 address match/error interrupts.
    * @note   Peripheral configuration is minimal configuration from reset values.
    *         Thus, some useless LL unitary functions calls below are provided as
    *         commented examples - setting is default configuration from reset.
    * @param  None
    * @retval None
    */
  void Configure_I2C_Slave(void)
  {
    /* (1) Enables GPIO clock and configures the I2C2 pins **********************/
    /*    (SCL on PB.10, SDA on PB.11)                     **********************/
  
    /* Enable the peripheral clock of GPIOB */
    LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOB);
  
    /* Configure SCL Pin as : Alternate function, High Speed, Open drain, Pull up */
    LL_GPIO_SetPinMode(GPIOB, LL_GPIO_PIN_10, LL_GPIO_MODE_ALTERNATE);
    LL_GPIO_SetAFPin_8_15(GPIOB, LL_GPIO_PIN_10, LL_GPIO_AF_4);
    LL_GPIO_SetPinSpeed(GPIOB, LL_GPIO_PIN_10, LL_GPIO_SPEED_FREQ_HIGH);
    LL_GPIO_SetPinOutputType(GPIOB, LL_GPIO_PIN_10, LL_GPIO_OUTPUT_OPENDRAIN);
    LL_GPIO_SetPinPull(GPIOB, LL_GPIO_PIN_10, LL_GPIO_PULL_UP);
  
    /* Configure SDA Pin as : Alternate function, High Speed, Open drain, Pull up */
    LL_GPIO_SetPinMode(GPIOB, LL_GPIO_PIN_11, LL_GPIO_MODE_ALTERNATE);
    LL_GPIO_SetAFPin_8_15(GPIOB, LL_GPIO_PIN_11, LL_GPIO_AF_4);
    LL_GPIO_SetPinSpeed(GPIOB, LL_GPIO_PIN_11, LL_GPIO_SPEED_FREQ_HIGH);
    LL_GPIO_SetPinOutputType(GPIOB, LL_GPIO_PIN_11, LL_GPIO_OUTPUT_OPENDRAIN);
    LL_GPIO_SetPinPull(GPIOB, LL_GPIO_PIN_11, LL_GPIO_PULL_UP);
  
    /* (2) Enable the I2C2 peripheral clock and I2C2 clock source ***************/
  
    /* Enable the peripheral clock for I2C2 */
    LL_APB1_GRP1_EnableClock(LL_APB1_GRP1_PERIPH_I2C2);
  
    /* Set I2C2 clock source as SYSCLK */
    LL_RCC_SetI2CClockSource(LL_RCC_I2C2_CLKSOURCE_SYSCLK);
  
    /* (3) Configure NVIC for I2C2 **********************************************/
  
    /* Configure Event IT:
     *  - Set priority for I2C2_EV_IRQn
     *  - Enable I2C2_EV_IRQn
     */
    NVIC_SetPriority(I2C2_EV_IRQn, 0);  
    NVIC_EnableIRQ(I2C2_EV_IRQn);
  
    /* Configure Error IT:
     *  - Set priority for I2C2_ER_IRQn
     *  - Enable I2C2_ER_IRQn
     */
    NVIC_SetPriority(I2C2_ER_IRQn, 0);  
    NVIC_EnableIRQ(I2C2_ER_IRQn);
  
    /* (4) Configure I2C2 functional parameters *********************************/
  
    /* Reset I2C2 data registers */
    if (LL_I2C_DeInit(I2C2) != SUCCESS) 
    {
      /* Initialization Error */
      LED_Blinking(LED_BLINK_ERROR);
    }
  
    /* Enable Clock stretching */
    /* Reset Value is Clock stretching enabled */
    //LL_I2C_EnableClockStretching(I2C2);
  
    /* Enable General Call                  */
    /* Reset Value is General Call disabled */
    //LL_I2C_EnableGeneralCall(I2C2);
  
    /* Configure the 7bits Own Address2               */
    /* Reset Values of :
     *     - OwnAddress2 is 0x00
     *     - OwnAddrMask is LL_I2C_OWNADDRESS2_NOMASK
     *     - Own Address2 is disabled
     */
    //LL_I2C_SetOwnAddress2(I2C2, 0x00, LL_I2C_OWNADDRESS2_NOMASK);
    //LL_I2C_DisableOwnAddress2(I2C2);
  
    /* Enable Peripheral in I2C mode */
    /* Reset Value is I2C mode */
    //LL_I2C_SetMode(I2C2, LL_I2C_MODE_I2C);
  
    /* Set fields of initialization structure:
     *  - Peripheral Mode     = Mode I2C
     *  - Timing Value        = fast Mode @400kHz with I2CCLK = 216 MHz
     *                          rise time = 100ns, 
     *                          fall time = 10ns
     *  - Analog Filter       = Enabled
     *  - Digital Filter      = Disabled
     *  - Own Address1        = SLAVE_OWN_ADDRESS
     *  - Type of Acknowledge = Acknowledge bytes/address received
     *  - Own Address 1 Size  = Slave Address in 7-bit
    */
    i2c_initstruct.PeripheralMode  = LL_I2C_MODE_I2C;
    i2c_initstruct.Timing          = I2C_TIMING;
    i2c_initstruct.AnalogFilter    = LL_I2C_ANALOGFILTER_ENABLE;
    i2c_initstruct.DigitalFilter   = 0x00;
    i2c_initstruct.OwnAddress1     = SLAVE_OWN_ADDRESS;
    i2c_initstruct.TypeAcknowledge = LL_I2C_ACK;
    i2c_initstruct.OwnAddrSize     = LL_I2C_OWNADDRESS1_7BIT;
  
    /* Initialize I2C instance according to parameters defined in initialization structure. */  
    if (LL_I2C_Init(I2C2, &i2c_initstruct) != SUCCESS)
    {
      /* Initialization Error */
      LED_Blinking(LED_BLINK_ERROR);
    }
  
    /* (5) Enable I2C2 address match/error interrupts:
     *  - Enable Address Match Interrupt
     *  - Enable Not acknowledge received interrupt
     *  - Enable Error interrupts
     *  - Enable Stop interrupt
     */
    LL_I2C_EnableIT_ADDR(I2C2);
    LL_I2C_EnableIT_NACK(I2C2);
    LL_I2C_EnableIT_ERR(I2C2);
    LL_I2C_EnableIT_STOP(I2C2);
  }
  
  /**
    * @brief  This function configures I2C1 in Master mode.
    * @note   This function is used to :
    *         -1- Enables GPIO clock and configures the I2C1 pins.
    *         -2- Enable the I2C1 peripheral clock and I2C1 clock source.
    *         -3- Configure NVIC for I2C1.
    *         -4- Configure and Enable I2C1 functional parameters.
    *         -5- Enable I2C1 transfer complete/error interrupts.
    * @note   Peripheral configuration is minimal configuration from reset values.
    *         Thus, some useless LL unitary functions calls below are provided as
    *         commented examples - setting is default configuration from reset.
    * @param  None
    * @retval None
    */
  void Configure_I2C_Master(void)
  {
    /* (1) Enables GPIO clock and configures the I2C1 pins **********************/
    /*    (SCL on PB.6, SDA on PB.9)                     **********************/
  
    /* Enable the peripheral clock of GPIOB */
    LL_AHB1_GRP1_EnableClock(LL_AHB1_GRP1_PERIPH_GPIOB);
  
    /* Configure SCL Pin as : Alternate function, High Speed, Open drain, Pull up */
    LL_GPIO_SetPinMode(GPIOB, LL_GPIO_PIN_6, LL_GPIO_MODE_ALTERNATE);
    LL_GPIO_SetAFPin_0_7(GPIOB, LL_GPIO_PIN_6, LL_GPIO_AF_4);
    LL_GPIO_SetPinSpeed(GPIOB, LL_GPIO_PIN_6, LL_GPIO_SPEED_FREQ_HIGH);
    LL_GPIO_SetPinOutputType(GPIOB, LL_GPIO_PIN_6, LL_GPIO_OUTPUT_OPENDRAIN);
    LL_GPIO_SetPinPull(GPIOB, LL_GPIO_PIN_6, LL_GPIO_PULL_UP);
  
    /* Configure SDA Pin as : Alternate function, High Speed, Open drain, Pull up */
    LL_GPIO_SetPinMode(GPIOB, LL_GPIO_PIN_9, LL_GPIO_MODE_ALTERNATE);
    LL_GPIO_SetAFPin_8_15(GPIOB, LL_GPIO_PIN_9, LL_GPIO_AF_4);
    LL_GPIO_SetPinSpeed(GPIOB, LL_GPIO_PIN_9, LL_GPIO_SPEED_FREQ_HIGH);
    LL_GPIO_SetPinOutputType(GPIOB, LL_GPIO_PIN_9, LL_GPIO_OUTPUT_OPENDRAIN);
    LL_GPIO_SetPinPull(GPIOB, LL_GPIO_PIN_9, LL_GPIO_PULL_UP);
  
    /* (2) Enable the I2C1 peripheral clock and I2C1 clock source ***************/
  
    /* Enable the peripheral clock for I2C1 */
    LL_APB1_GRP1_EnableClock(LL_APB1_GRP1_PERIPH_I2C1);
  
    /* Set I2C1 clock source as SYSCLK */
    LL_RCC_SetI2CClockSource(LL_RCC_I2C1_CLKSOURCE_SYSCLK);
  
    /* (3) Configure NVIC for I2C1 **********************************************/
  
    /* Configure Event IT:
     *  - Set priority for I2C1_EV_IRQn
     *  - Enable I2C1_EV_IRQn
     */
    NVIC_SetPriority(I2C1_EV_IRQn, 0);  
    NVIC_EnableIRQ(I2C1_EV_IRQn);
  
    /* Configure Error IT:
     *  - Set priority for I2C1_ER_IRQn
     *  - Enable I2C1_ER_IRQn
     */
    NVIC_SetPriority(I2C1_ER_IRQn, 0);  
    NVIC_EnableIRQ(I2C1_ER_IRQn);
  
    /* (4) Configure I2C1 functional parameters ********************************/
    /* Reset I2C1 data registers */
    if (LL_I2C_DeInit(I2C1) != SUCCESS) 
    {
      /* Initialization Error */
      LED_Blinking(LED_BLINK_ERROR);
    }
  
    /* Enable General Call                  */
    /* Reset Value is General Call disabled */
    //LL_I2C_EnableGeneralCall(I2C1);
  
    /* Configure the 7bits Own Address2               */
    /* Reset Values of :
     *     - OwnAddress2 is 0x00
     *     - OwnAddrMask is LL_I2C_OWNADDRESS2_NOMASK
     *     - Own Address2 is disabled
     */
    //LL_I2C_SetOwnAddress2(I2C1, 0x00, LL_I2C_OWNADDRESS2_NOMASK);
    //LL_I2C_DisableOwnAddress2(I2C1);
  
    /* Configure the Master to operate in 7-bit or 10-bit addressing mode */
    /* Reset Value is LL_I2C_ADDRESSING_MODE_7BIT                         */
    //LL_I2C_SetMasterAddressingMode(I2C1, LL_I2C_ADDRESSING_MODE_7BIT);
  
    /* Enable Peripheral in I2C mode */
    /* Reset Value is I2C mode */
    //LL_I2C_SetMode(I2C1, LL_I2C_MODE_I2C);
  
    /* Set fields of initialization structure:
     *  - Peripheral Mode     = Mode I2C
     *  - Timing Value        = fast Mode @400kHz with I2CCLK = 216 MHz
     *                          rise time = 100ns, 
     *                          fall time = 10ns
     *  - Analog Filter       = Enabled
     *  - Digital Filter      = Disabled
     *  - Own Address1        = No own address 1
     *  - Type of Acknowledge = Acknowledge bytes/address received
     *  - Own Address 1 Size  = default value Slave Address in 7-bit
    */
    i2c_initstruct.PeripheralMode  = LL_I2C_MODE_I2C;
    i2c_initstruct.Timing          = I2C_TIMING;
    i2c_initstruct.AnalogFilter    = LL_I2C_ANALOGFILTER_ENABLE;
    i2c_initstruct.DigitalFilter   = 0x00;
    i2c_initstruct.OwnAddress1     = 0x00;
    i2c_initstruct.TypeAcknowledge = LL_I2C_ACK;
    i2c_initstruct.OwnAddrSize     = LL_I2C_OWNADDRESS1_7BIT;
  
    /* Initialize I2C instance according to parameters defined in initialization structure. */  
    if (LL_I2C_Init(I2C1, &i2c_initstruct) != SUCCESS)
    {
      /* Initialization Error */
      LED_Blinking(LED_BLINK_ERROR);
    }
  
    /* (5) Enable I2C1 transfer complete/error interrupts:
     *  - Enable Receive Interrupt
     *  - Enable Not acknowledge received interrupt
     *  - Enable Error interrupts
     *  - Enable Stop interrupt
     */
    LL_I2C_EnableIT_RX(I2C1);
    LL_I2C_EnableIT_NACK(I2C1);
    LL_I2C_EnableIT_ERR(I2C1);
    LL_I2C_EnableIT_STOP(I2C1);
  }
  
  /**
    * @brief  Initialize LED1.
    * @param  None
    * @retval None
    */
  void LED_Init(void)
  {
    /* Enable the LED1 Clock */
    LED1_GPIO_CLK_ENABLE();
  
    /* Configure IO in output push-pull mode to drive external LED1 */
    LL_GPIO_SetPinMode(LED1_GPIO_PORT, LED1_PIN, LL_GPIO_MODE_OUTPUT);
    /* Reset value is LL_GPIO_OUTPUT_PUSHPULL */
    //LL_GPIO_SetPinOutputType(LED1_GPIO_PORT, LED1_PIN, LL_GPIO_OUTPUT_PUSHPULL);
    /* Reset value is LL_GPIO_SPEED_FREQ_LOW */
    //LL_GPIO_SetPinSpeed(LED1_GPIO_PORT, LED1_PIN, LL_GPIO_SPEED_FREQ_LOW);
    /* Reset value is LL_GPIO_PULL_NO */
    //LL_GPIO_SetPinPull(LED1_GPIO_PORT, LED1_PIN, LL_GPIO_PULL_NO);
  }
  
  /**
    * @brief  Turn-on LED1.
    * @param  None
    * @retval None
    */
  void LED_On(void)
  {
    /* Turn LED1 on */
    LL_GPIO_SetOutputPin(LED1_GPIO_PORT, LED1_PIN);
  }
  
  /**
    * @brief  Turn-off LED1.
    * @param  None
    * @retval None
    */
  void LED_Off(void)
  {
    /* Turn LED1 off */
    LL_GPIO_ResetOutputPin(LED1_GPIO_PORT, LED1_PIN);
  }
  
  /**
    * @brief  Set LED1 to Blinking mode for an infinite loop (toggle period based on value provided as input parameter).
    * @param  Period : Period of time (in ms) between each toggling of LED
    *   This parameter can be user defined values. Pre-defined values used in that example are :   
    *     @arg LED_BLINK_FAST : Fast Blinking
    *     @arg LED_BLINK_SLOW : Slow Blinking
    *     @arg LED_BLINK_ERROR : Error specific Blinking
    * @retval None
    */
  void LED_Blinking(uint32_t Period)
  {
    /* Turn LED1 on */
    LL_GPIO_SetOutputPin(LED1_GPIO_PORT, LED1_PIN);
  
    /* Toggle IO in an infinite loop */
    while (1)
    {
      LL_GPIO_TogglePin(LED1_GPIO_PORT, LED1_PIN);  
      LL_mDelay(Period);
    }
  }
  
  /**
    * @brief  Configures User push-button in GPIO or EXTI Line Mode.
    * @param  None 
    * @retval None
    */
  void UserButton_Init(void)
  {
    /* Enable the BUTTON Clock */
    USER_BUTTON_GPIO_CLK_ENABLE();
  
    /* Configure GPIO for BUTTON */
    LL_GPIO_SetPinMode(USER_BUTTON_GPIO_PORT, USER_BUTTON_PIN, LL_GPIO_MODE_INPUT);
    LL_GPIO_SetPinPull(USER_BUTTON_GPIO_PORT, USER_BUTTON_PIN, LL_GPIO_PULL_NO);
  
    /* Connect External Line to the GPIO*/
    USER_BUTTON_SYSCFG_SET_EXTI();
  
    /* Enable a rising trigger External line 13 Interrupt */
    USER_BUTTON_EXTI_LINE_ENABLE();
    USER_BUTTON_EXTI_FALLING_TRIG_ENABLE();
  
    /* Configure NVIC for USER_BUTTON_EXTI_IRQn */
    NVIC_EnableIRQ(USER_BUTTON_EXTI_IRQn); 
    NVIC_SetPriority(USER_BUTTON_EXTI_IRQn,0x03);  
  }
  
  /**
    * @brief  Wait for User push-button press to start transfer.
    * @param  None 
    * @retval None
    */
    /*  */
  void WaitForUserButtonPress(void)
  {
    while (ubButtonPress == 0)
    {
      LL_GPIO_TogglePin(LED1_GPIO_PORT, LED1_PIN);
      LL_mDelay(LED_BLINK_FAST);
    }
    /* Turn LED1 off */
    LL_GPIO_ResetOutputPin(LED1_GPIO_PORT, LED1_PIN);
  }
  
  /**
    * @brief  This Function handle Master events to perform a reception process
    * @note  This function is composed in one step :
    *        -1- Initiate a Start condition to the Slave device.
    * @param  None
    * @retval None
    */
  void Handle_I2C_Master(void)
  {
    /* (1) Initiate a Start condition to the Slave device ***********************/
  
    /* Master Generate Start condition for a read request:
     *  - to the Slave with a 7-Bit SLAVE_OWN_ADDRESS
     *  - with a auto stop condition generation when receive 1 byte
     */
    LL_I2C_HandleTransfer(I2C1, SLAVE_OWN_ADDRESS, LL_I2C_ADDRSLAVE_7BIT, 1, LL_I2C_MODE_AUTOEND, LL_I2C_GENERATE_START_READ);
  }
  
  /**
    * @brief  System Clock Configuration
    *         The system Clock is configured as follow :
    *            System Clock source            = PLL (HSE)
    *            SYSCLK(Hz)                     = 216000000
    *            HCLK(Hz)                       = 216000000
    *            AHB Prescaler                  = 1
    *            APB1 Prescaler                 = 4
    *            APB2 Prescaler                 = 2
    *            HSI Frequency(Hz)              = 8000000
    *            PLL_M                          = 8
    *            PLL_N                          = 432
    *            PLL_P                          = 2
    *            VDD(V)                         = 3.3
    *            Main regulator output voltage  = Scale1 mode
    *            Flash Latency(WS)              = 7
    * @param  None
    * @retval None
    */
  void SystemClock_Config(void)
  {
    /* Enable HSE clock */
    LL_RCC_HSE_EnableBypass();
    LL_RCC_HSE_Enable();
    while(LL_RCC_HSE_IsReady() != 1)
    {
    };
  
    /* Set FLASH latency */
    LL_FLASH_SetLatency(LL_FLASH_LATENCY_7);
  
    /* Enable PWR clock */
    LL_APB1_GRP1_EnableClock(LL_APB1_GRP1_PERIPH_PWR);
  
    /* Activation OverDrive Mode */
    LL_PWR_EnableOverDriveMode();
    while(LL_PWR_IsActiveFlag_OD() != 1)
    {
    };
  
    /* Activation OverDrive Switching */
    LL_PWR_EnableOverDriveSwitching();
    while(LL_PWR_IsActiveFlag_ODSW() != 1)
    {
    };
  
    /* Main PLL configuration and activation */
    LL_RCC_PLL_ConfigDomain_SYS(LL_RCC_PLLSOURCE_HSE, LL_RCC_PLLM_DIV_8, 432, LL_RCC_PLLP_DIV_2);
    LL_RCC_PLL_Enable();
    while(LL_RCC_PLL_IsReady() != 1)
    {
    };
  
    /* Sysclk activation on the main PLL */
    LL_RCC_SetAHBPrescaler(LL_RCC_SYSCLK_DIV_1);
    LL_RCC_SetSysClkSource(LL_RCC_SYS_CLKSOURCE_PLL);
    while(LL_RCC_GetSysClkSource() != LL_RCC_SYS_CLKSOURCE_STATUS_PLL)
    {
    };
  
    /* Set APB1 & APB2 prescaler */
    LL_RCC_SetAPB1Prescaler(LL_RCC_APB1_DIV_4);
    LL_RCC_SetAPB2Prescaler(LL_RCC_APB2_DIV_2);
  
    /* Set systick to 1ms */
    SysTick_Config(216000000 / 1000);
  
    /* Update CMSIS variable (which can be updated also through SystemCoreClockUpdate function) */
    SystemCoreClock = 216000000;
  }
  /******************************************************************************/
  /*   IRQ HANDLER TREATMENT Functions                                          */
  /******************************************************************************/
  /**
    * @brief  Function to manage User push-button
    * @param  None
    * @retval None
    */
  void UserButton_Callback(void)
  {
    /* Update User push-button variable : to be checked in waiting loop in main program */
    ubButtonPress = 1;
  }
  
  /**
    * @brief  Function called from I2C IRQ Handler when TXIS flag is set
    *         Function is in charge of transmit a byte on I2C lines.
    * @param  None
    * @retval None
    */
  void Slave_Ready_To_Transmit_Callback(void)
  {
    /* Send the Byte requested by the Master */
    LL_I2C_TransmitData8(I2C2, SLAVE_BYTE_TO_SEND);
  }
  
  /**
    * @brief  Function called from I2C IRQ Handler when RXNE flag is set
    *         Function is in charge of reading byte received on I2C lines.
    * @param  None
    * @retval None
    */
  void Master_Reception_Callback(void)
  {
    /* Read character in Receive Data register.
    RXNE flag is cleared by reading data in RXDR register */
    aReceiveBuffer[ubReceiveIndex++] = LL_I2C_ReceiveData8(I2C1);
  }
  
  /**
    * @brief  Function called from I2C IRQ Handler when STOP flag is set
    *         Function is in charge of checking data received,
    *         LED1 is On if data are correct.
    * @param  None
    * @retval None
    */
  void Master_Complete_Callback(void)
  {
    /* Read Received character.
    RXNE flag is cleared by reading of RXDR register */
    if(aReceiveBuffer[ubReceiveIndex-1] == SLAVE_BYTE_TO_SEND)
    {
      /* Turn LED1 On:
       * - Expected byte has been received
       * - Master Rx sequence completed successfully
       */
      LED_On();
    }
    else
    {
      /* Call Error function */
      Error_Callback();
    }
  }
  
  /**
    * @brief  Function called in case of error detected in I2C IT Handler
    * @param  None
    * @retval None
    */
  void Error_Callback(void)
  {
    /* Disable I2C2_EV_IRQn and I2C1_EV_IRQn */
    NVIC_DisableIRQ(I2C2_EV_IRQn);
    NVIC_DisableIRQ(I2C1_EV_IRQn);
  
    /* Disable I2C2_ER_IRQn and I2C1_ER_IRQn */
    NVIC_DisableIRQ(I2C2_ER_IRQn);
    NVIC_DisableIRQ(I2C1_ER_IRQn);
  
    /* Unexpected event : Set LED1 to Blinking mode to indicate error occurs */
    LED_Blinking(LED_BLINK_ERROR);
  }
  
  /**
    * @brief  CPU L1-Cache enable.
    * @param  None
    * @retval None
    */
  static void CPU_CACHE_Enable(void)
  {
    /* Enable I-Cache */
    SCB_EnableICache();
  
    /* Enable D-Cache */
    SCB_EnableDCache();
  }
  
  #ifdef  USE_FULL_ASSERT
  
  /**
    * @brief  Reports the name of the source file and the source line number
    *         where the assert_param error has occurred.
    * @param  file: pointer to the source file name
    * @param  line: assert_param error line source number
    * @retval None
    */
  void assert_failed(uint8_t *file, uint32_t line)
  {
    /* User can add his own implementation to report the file name and line number,
       ex: printf("Wrong parameters value: file %s on line %d", file, line) */
  
    /* Infinite loop */
    while (1)
    {
    }
  }
  #endif
  
  /**
    * @}
    */
  
  /**
    * @}
    */
  
  