while (HAL_I2C_Slave_Transmit_IT( &hi2c1, TxBuf, (sizeof(TxBuf)/sizeof(TxBuf[0])) ) != HAL_OK)
    ;

  /*##-2- Put I2C peripheral in reception process ###########################*/  
  if(HAL_I2C_Slave_Receive_IT(&I2cHandle, (uint8_t *)aRxBuffer, RXBUFFERSIZE) != HAL_OK)
  {
    /* Transfer error in transmission process */
    Error_Handler();        
  }
  
  /*##-3- Wait for the end of the transfer ###################################*/  
  /*  Before starting a new communication transfer, you need to check the current  
      state of the peripheral; if it’s busy you need to wait for the end of current
      transfer before starting a new one.
      For simplicity reasons, this example is just waiting till the end of the
      transfer, but application may perform other tasks while transfer operation
      is ongoing. */  
  while (HAL_I2C_GetState(&I2cHandle) != HAL_I2C_STATE_READY)
  {
  }

  /*##-4- Start the transmission process #####################################*/  
  /* While the I2C in reception process, user can transmit data through
     "aTxBuffer" buffer */
  if(HAL_I2C_Slave_Transmit_IT(&I2cHandle, (uint8_t*)aTxBuffer, TXBUFFERSIZE)!= HAL_OK)
  {
    /* Transfer error in transmission process */
    Error_Handler();    
  }