text: /**
    ******************************************************************************
    * @file    stm32l1xx_usart.c
    * @author  MCD Application Team
    * @version V1.1.0
    * @date    24-January-2012
    * @brief   This file provides firmware functions to manage the following 
    *          functionalities of the Universal synchronous asynchronous receiver
    *          transmitter (USART):           
    *           + Initialization and Configuration
    *           + Data transfers
    *           + Multi-Processor Communication
    *           + LIN mode
    *           + Half-duplex mode
    *           + Smartcard mode
    *           + IrDA mode
    *           + DMA transfers management
    *           + Interrupts and flags management 
    *           
    *  @verbatim
   ===============================================================================
                         ##### How to use this driver #####
   ===============================================================================
      [..]
          (#) Enable peripheral clock using
              RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1, ENABLE) function for
              USART1 or using RCC_APB1PeriphClockCmd(RCC_APB1Periph_USARTx, ENABLE)
              function for USART2 and USART3.
          (#) According to the USART mode, enable the GPIO clocks using
              RCC_AHBPeriphClockCmd() function. (The I/O can be TX, RX, CTS,
              or and SCLK).
          (#) Peripheral's alternate function:
              (++) Connect the pin to the desired peripherals' Alternate
                   Function (AF) using GPIO_PinAFConfig() function.
              (++) Configure the desired pin in alternate function by:
                   GPIO_InitStruct->GPIO_Mode = GPIO_Mode_AF.
              (++) Select the type, pull-up/pull-down and output speed via
                   GPIO_PuPd, GPIO_OType and GPIO_Speed members.
              (++) Call GPIO_Init() function.
          (#) Program the Baud Rate, Word Length , Stop Bit, Parity, Hardware
                 flow control and Mode(Receiver/Transmitter) using the SPI_Init()
                 function.
          (#) For synchronous mode, enable the clock and program the polarity,
              phase and last bit using the USART_ClockInit() function.
          (#) Enable the NVIC and the corresponding interrupt using the function
              USART_ITConfig() if you need to use interrupt mode.
          (#) When using the DMA mode.
              (++) Configure the DMA using DMA_Init() function.
              (++) Active the needed channel Request using USART_DMACmd() function.
          (#) Enable the USART using the USART_Cmd() function.
          (#) Enable the DMA using the DMA_Cmd() function, when using DMA mode.
      [..]
          Refer to Multi-Processor, LIN, half-duplex, Smartcard, IrDA sub-sections
          for more details.
    
  @endverbatim
            
    ******************************************************************************
     @attention
    *
    * THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
    * WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE
    * TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY
    * DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING
    * FROM THE CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE
    * CODING INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
    *
    * FOR MORE INFORMATION PLEASE READ CAREFULLY THE LICENSE AGREEMENT FILE
    * LOCATED IN THE ROOT DIRECTORY OF THIS FIRMWARE PACKAGE.
    *
    * <h2><center>&copy; COPYRIGHT 2012 STMicroelectronics</center></h2>
    ******************************************************************************
    */
  
  /* Includes ------------------------------------------------------------------*/
  #include "stm32l1xx_usart.h"
  #include "stm32l1xx_rcc.h"
  
  /** @addtogroup STM32L1xx_StdPeriph_Driver
    * @{
    */
  
  /** @defgroup USART 
    * @brief USART driver modules
    * @{
    */
  
  /* Private typedef -----------------------------------------------------------*/
  /* Private define ------------------------------------------------------------*/
  
  /*!< USART CR1 register clear Mask ((~(uint16_t)0xE9F3)) */
  #define CR1_CLEAR_MASK            ((uint16_t)(USART_CR1_M | USART_CR1_PCE | \
                                                USART_CR1_PS | USART_CR1_TE | \
                                                USART_CR1_RE))
  
  /*!< USART CR2 register clock bits clear Mask ((~(uint16_t)0xF0FF)) */
  #define CR2_CLOCK_CLEAR_MASK      ((uint16_t)(USART_CR2_CLKEN | USART_CR2_CPOL | \
                                                USART_CR2_CPHA | USART_CR2_LBCL))
  
  /*!< USART CR3 register clear Mask ((~(uint16_t)0xFCFF)) */
  #define CR3_CLEAR_MASK            ((uint16_t)(USART_CR3_RTSE | USART_CR3_CTSE))
  
  /*!< USART Interrupts mask */
  #define IT_MASK                   ((uint16_t)0x001F)
  
  /* Private macro -------------------------------------------------------------*/
  /* Private variables ---------------------------------------------------------*/
  /* Private function prototypes -----------------------------------------------*/
  /* Private functions ---------------------------------------------------------*/
  
  /** @defgroup USART_Private_Functions
    * @{
    */
  
  /** @defgroup USART_Group1 Initialization and Configuration functions
   *  @brief   Initialization and Configuration functions 
   *
  @verbatim
   ===============================================================================
            ##### Initialization and Configuration functions #####
   ===============================================================================
      [..]
          This subsection provides a set of functions allowing to initialize the USART 
          in asynchronous and in synchronous modes.
          (+) For the asynchronous mode only these parameters can be configured: 
          (+) Baud Rate.
          (+) Word Length.
          (+) Stop Bit.
          (+) Parity: If the parity is enabled, then the MSB bit of the data written
            in the data register is transmitted but is changed by the parity bit.
            Depending on the frame length defined by the M bit (8-bits or 9-bits),
            the possible USART frame formats are as listed in the following table:
      [..]
     +-------------------------------------------------------------+
     |   M bit |  PCE bit  |            USART frame                |
     |---------------------|---------------------------------------|
     |    0    |    0      |    | SB | 8 bit data | STB |          |
     |---------|-----------|---------------------------------------|
     |    0    |    1      |    | SB | 7 bit data | PB | STB |     |
     |---------|-----------|---------------------------------------|
     |    1    |    0      |    | SB | 9 bit data | STB |          |
     |---------|-----------|---------------------------------------|
     |    1    |    1      |    | SB | 8 bit data | PB | STB |     |
     +-------------------------------------------------------------+
      [..]
          (+) Hardware flow control.
          (+) Receiver/transmitter modes.
      [..] The USART_Init() function follows the USART  asynchronous configuration 
           procedure(details for the procedure are available in reference manual 
           (RM0038)).
          (+) For the synchronous mode in addition to the asynchronous mode parameters
              these parameters should be also configured:
              (++) USART Clock Enabled.
              (++) USART polarity.
              (++) USART phase.
              (++) USART LastBit.
      [..] These parameters can be configured using the USART_ClockInit() function.
  
  @endverbatim
    * @{
    */
    
  /**
    * @brief  Deinitializes the USARTx peripheral registers to their default reset values.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values: USART1, USART2, USART3, 
    *   UART4 or UART5.
    * @retval None.
    */
  void USART_DeInit(USART_TypeDef* USARTx)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
  
    if (USARTx == USART1)
    {
      RCC_APB2PeriphResetCmd(RCC_APB2Periph_USART1, ENABLE);
      RCC_APB2PeriphResetCmd(RCC_APB2Periph_USART1, DISABLE);
    }
    else if (USARTx == USART2)
    {
      RCC_APB1PeriphResetCmd(RCC_APB1Periph_USART2, ENABLE);
      RCC_APB1PeriphResetCmd(RCC_APB1Periph_USART2, DISABLE);
    }
    else if (USARTx == USART3)
    {
      RCC_APB1PeriphResetCmd(RCC_APB1Periph_USART3, ENABLE);
      RCC_APB1PeriphResetCmd(RCC_APB1Periph_USART3, DISABLE);
    }    
    else if (USARTx == UART4)
    {
      RCC_APB1PeriphResetCmd(RCC_APB1Periph_UART4, ENABLE);
      RCC_APB1PeriphResetCmd(RCC_APB1Periph_UART4, DISABLE);
    }    
    else
    {
      if (USARTx == UART5)
      { 
        RCC_APB1PeriphResetCmd(RCC_APB1Periph_UART5, ENABLE);
        RCC_APB1PeriphResetCmd(RCC_APB1Periph_UART5, DISABLE);
      }
    }   
  }
  
  /**
    * @brief  Initializes the USARTx peripheral according to the specified
    *   parameters in the USART_InitStruct.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values: USART1, USART2, USART3, 
    *   UART4 or UART5.
    * @param  USART_InitStruct: pointer to a USART_InitTypeDef structure that 
    *        contains the configuration information for the specified USART peripheral.
    * @retval None.
    */
  void USART_Init(USART_TypeDef* USARTx, USART_InitTypeDef* USART_InitStruct)
  {
    uint32_t tmpreg = 0x00, apbclock = 0x00;
    uint32_t integerdivider = 0x00;
    uint32_t fractionaldivider = 0x00;
    RCC_ClocksTypeDef RCC_ClocksStatus;
  
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_BAUDRATE(USART_InitStruct->USART_BaudRate));  
    assert_param(IS_USART_WORD_LENGTH(USART_InitStruct->USART_WordLength));
    assert_param(IS_USART_STOPBITS(USART_InitStruct->USART_StopBits));
    assert_param(IS_USART_PARITY(USART_InitStruct->USART_Parity));
    assert_param(IS_USART_MODE(USART_InitStruct->USART_Mode));
    assert_param(IS_USART_HARDWARE_FLOW_CONTROL(USART_InitStruct->USART_HardwareFlowControl));
  
    /* The hardware flow control is available only for USART1, USART2 and USART3 */
    if (USART_InitStruct->USART_HardwareFlowControl != USART_HardwareFlowControl_None)
    {
      assert_param(IS_USART_123_PERIPH(USARTx));
    }
     
  /*---------------------------- USART CR2 Configuration -----------------------*/
    tmpreg = USARTx->CR2;
    /* Clear STOP[13:12] bits */
    tmpreg &= (uint32_t)~((uint32_t)USART_CR2_STOP);
  
    /* Configure the USART Stop Bits, Clock, CPOL, CPHA and LastBit ------------*/
    /* Set STOP[13:12] bits according to USART_StopBits value */
    tmpreg |= (uint32_t)USART_InitStruct->USART_StopBits;
    
    /* Write to USART CR2 */
    USARTx->CR2 = (uint16_t)tmpreg;
  
  /*---------------------------- USART CR1 Configuration -----------------------*/
    tmpreg = USARTx->CR1;
    /* Clear M, PCE, PS, TE and RE bits */
    tmpreg &= (uint32_t)~((uint32_t)CR1_CLEAR_MASK);
  
    /* Configure the USART Word Length, Parity and mode ----------------------- */
    /* Set the M bits according to USART_WordLength value */
    /* Set PCE and PS bits according to USART_Parity value */
    /* Set TE and RE bits according to USART_Mode value */
    tmpreg |= (uint32_t)USART_InitStruct->USART_WordLength | USART_InitStruct->USART_Parity |
              USART_InitStruct->USART_Mode;
  
    /* Write to USART CR1 */
    USARTx->CR1 = (uint16_t)tmpreg;
  
  /*---------------------------- USART CR3 Configuration -----------------------*/  
    tmpreg = USARTx->CR3;
    /* Clear CTSE and RTSE bits */
    tmpreg &= (uint32_t)~((uint32_t)CR3_CLEAR_MASK);
  
    /* Configure the USART HFC -------------------------------------------------*/
    /* Set CTSE and RTSE bits according to USART_HardwareFlowControl value */
    tmpreg |= USART_InitStruct->USART_HardwareFlowControl;
  
    /* Write to USART CR3 */
    USARTx->CR3 = (uint16_t)tmpreg;
  
  /*---------------------------- USART BRR Configuration -----------------------*/
    /* Configure the USART Baud Rate -------------------------------------------*/
    RCC_GetClocksFreq(&RCC_ClocksStatus);
    if (USARTx == USART1) 
    {
      apbclock = RCC_ClocksStatus.PCLK2_Frequency;
    }
    else
    {
      apbclock = RCC_ClocksStatus.PCLK1_Frequency;
    }
  
    /* Determine the integer part */
    if ((USARTx->CR1 & USART_CR1_OVER8) != 0)
    {
      /* Integer part computing in case Oversampling mode is 8 Samples */
      integerdivider = ((25 * apbclock) / (2 * (USART_InitStruct->USART_BaudRate)));    
    }
    else /* if ((USARTx->CR1 & CR1_OVER8_Set) == 0) */
    {
      /* Integer part computing in case Oversampling mode is 16 Samples */
      integerdivider = ((25 * apbclock) / (4 * (USART_InitStruct->USART_BaudRate)));    
    }
    tmpreg = (integerdivider / 100) << 4;
  
    /* Determine the fractional part */
    fractionaldivider = integerdivider - (100 * (tmpreg >> 4));
  
    /* Implement the fractional part in the register */
    if ((USARTx->CR1 & USART_CR1_OVER8) != 0)
    {
      tmpreg |= ((((fractionaldivider * 8) + 50) / 100)) & ((uint8_t)0x07);
    }
    else /* if ((USARTx->CR1 & CR1_OVER8_Set) == 0) */
    {
      tmpreg |= ((((fractionaldivider * 16) + 50) / 100)) & ((uint8_t)0x0F);
    }
   
    /* Write to USART BRR */
    USARTx->BRR = (uint16_t)tmpreg;
  }
  
  /**
    * @brief  Fills each USART_InitStruct member with its default value.
    * @param  USART_InitStruct: pointer to a USART_InitTypeDef structure
    *   which will be initialized.
    * @retval None
    */
  void USART_StructInit(USART_InitTypeDef* USART_InitStruct)
  {
    /* USART_InitStruct members default value */
    USART_InitStruct->USART_BaudRate = 9600;
    USART_InitStruct->USART_WordLength = USART_WordLength_8b;
    USART_InitStruct->USART_StopBits = USART_StopBits_1;
    USART_InitStruct->USART_Parity = USART_Parity_No ;
    USART_InitStruct->USART_Mode = USART_Mode_Rx | USART_Mode_Tx;
    USART_InitStruct->USART_HardwareFlowControl = USART_HardwareFlowControl_None;  
  }
  
  /**
    * @brief  Initializes the USARTx peripheral Clock according to the 
    *         specified parameters in the USART_ClockInitStruct.
    * @param  USARTx: where x can be 1, 2, 3 to select the USART peripheral.
    * @param  USART_ClockInitStruct: pointer to a USART_ClockInitTypeDef
    *         structure that contains the configuration information for the specified 
    *         USART peripheral.
    * @note The Smart Card and Synchronous modes are not available for UART4 and UART5.
    * @retval None.
    */
  void USART_ClockInit(USART_TypeDef* USARTx, USART_ClockInitTypeDef* USART_ClockInitStruct)
  {
    uint32_t tmpreg = 0x00;
    /* Check the parameters */
    assert_param(IS_USART_123_PERIPH(USARTx));
    assert_param(IS_USART_CLOCK(USART_ClockInitStruct->USART_Clock));
    assert_param(IS_USART_CPOL(USART_ClockInitStruct->USART_CPOL));
    assert_param(IS_USART_CPHA(USART_ClockInitStruct->USART_CPHA));
    assert_param(IS_USART_LASTBIT(USART_ClockInitStruct->USART_LastBit));
    
  /*---------------------------- USART CR2 Configuration -----------------------*/
    tmpreg = USARTx->CR2;
    /* Clear CLKEN, CPOL, CPHA and LBCL bits */
    tmpreg &= (uint32_t)~((uint32_t)CR2_CLOCK_CLEAR_MASK);
    /* Configure the USART Clock, CPOL, CPHA and LastBit ------------*/
    /* Set CLKEN bit according to USART_Clock value */
    /* Set CPOL bit according to USART_CPOL value */
    /* Set CPHA bit according to USART_CPHA value */
    /* Set LBCL bit according to USART_LastBit value */
    tmpreg |= (uint32_t)USART_ClockInitStruct->USART_Clock | USART_ClockInitStruct->USART_CPOL | 
                   USART_ClockInitStruct->USART_CPHA | USART_ClockInitStruct->USART_LastBit;
    /* Write to USART CR2 */
    USARTx->CR2 = (uint16_t)tmpreg;
  }
  
  /**
    * @brief  Fills each USART_ClockInitStruct member with its default value.
    * @param  USART_ClockInitStruct: pointer to a USART_ClockInitTypeDef
    *   structure which will be initialized.
    * @retval None
    */
  void USART_ClockStructInit(USART_ClockInitTypeDef* USART_ClockInitStruct)
  {
    /* USART_ClockInitStruct members default value */
    USART_ClockInitStruct->USART_Clock = USART_Clock_Disable;
    USART_ClockInitStruct->USART_CPOL = USART_CPOL_Low;
    USART_ClockInitStruct->USART_CPHA = USART_CPHA_1Edge;
    USART_ClockInitStruct->USART_LastBit = USART_LastBit_Disable;
  }
  
  /**
    * @brief  Enables or disables the specified USART peripheral.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  NewState: new state of the USARTx peripheral.
    *         This parameter can be: ENABLE or DISABLE.
    * @retval None.
    */
  void USART_Cmd(USART_TypeDef* USARTx, FunctionalState NewState)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_FUNCTIONAL_STATE(NewState));
    
    if (NewState != DISABLE)
    {
      /* Enable the selected USART by setting the UE bit in the CR1 register */
      USARTx->CR1 |= USART_CR1_UE;
    }
    else
    {
      /* Disable the selected USART by clearing the UE bit in the CR1 register */
      USARTx->CR1 &= (uint16_t)~((uint16_t)USART_CR1_UE);
    }
  }
  
  /**
    * @brief  Sets the system clock prescaler.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  USART_Prescaler: specifies the prescaler clock. 
    * @note   The function is used for IrDA mode with UART4 and UART5.   
    * @retval None.
    */
  void USART_SetPrescaler(USART_TypeDef* USARTx, uint8_t USART_Prescaler)
  { 
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    
    /* Clear the USART prescaler */
    USARTx->GTPR &= USART_GTPR_GT;
    /* Set the USART prescaler */
    USARTx->GTPR |= USART_Prescaler;
  }
  
  /**
    * @brief  Enables or disables the USART's 8x oversampling mode.
    * @param USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *     USART1, USART2, USART3, UART4 or UART5.
    * @param NewState: new state of the USART 8x oversampling mode.
    *   This parameter can be: ENABLE or DISABLE.
    *
    * @note
    *   This function has to be called before calling USART_Init()
    *   function in order to have correct baudrate Divider value.
    * @retval None
    */
  void USART_OverSampling8Cmd(USART_TypeDef* USARTx, FunctionalState NewState)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_FUNCTIONAL_STATE(NewState));
    
    if (NewState != DISABLE)
    {
      /* Enable the 8x Oversampling mode by setting the OVER8 bit in the CR1 register */
      USARTx->CR1 |= USART_CR1_OVER8;
    }
    else
    {
      /* Disable the 8x Oversampling mode by clearing the OVER8 bit in the CR1 register */
      USARTx->CR1 &= (uint16_t)~((uint16_t)USART_CR1_OVER8);
    }
  }  
  
  /**
    * @brief  Enables or disables the USART's one bit sampling method.
    * @param USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param NewState: new state of the USART one bit sampling method.
    *   This parameter can be: ENABLE or DISABLE.
    * @retval None.
    */
  void USART_OneBitMethodCmd(USART_TypeDef* USARTx, FunctionalState NewState)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_FUNCTIONAL_STATE(NewState));
    
    if (NewState != DISABLE)
    {
      /* Enable the one bit method by setting the ONEBITE bit in the CR3 register */
      USARTx->CR3 |= USART_CR3_ONEBIT;
    }
    else
    {
      /* Disable the one bit method by clearing the ONEBITE bit in the CR3 register */
      USARTx->CR3 &= (uint16_t)~((uint16_t)USART_CR3_ONEBIT);
    }
  }
  
  /**
    * @}
    */
  
  /** @defgroup USART_Group2 Data transfers functions
   *  @brief   Data transfers functions 
   *
  @verbatim
   ===============================================================================
                      ##### Data transfers functions #####
   ===============================================================================
      [..] This subsection provides a set of functions allowing to manage 
           the USART data transfers.
      [..] During an USART reception, data shifts in least significant bit first 
           through the RX pin. In this mode, the USART_DR register consists of 
           a buffer (RDR) between the internal bus and the received shift register.
           When a transmission is taking place, a write instruction to 
           the USART_DR register stores the data in the TDR register and which is 
           copied in the shift register at the end of the current transmission.
      [..] The read access of the USART_DR register can be done using 
           the USART_ReceiveData() function and returns the RDR buffered value.
          Whereas a write access to the USART_DR can be done using USART_SendData()
          function and stores the written data into TDR buffer.
  
  @endverbatim
    * @{
    */
  
  /**
    * @brief  Transmits single data through the USARTx peripheral.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  Data: the data to transmit.
    * @retval None.
    */
  void USART_SendData(USART_TypeDef* USARTx, uint16_t Data)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_DATA(Data)); 
      
    /* Transmit Data */
    USARTx->DR = (Data & (uint16_t)0x01FF);
  }
  
  /**
    * @brief  Returns the most recent received data by the USARTx peripheral.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @retval The received data.
    */
  uint16_t USART_ReceiveData(USART_TypeDef* USARTx)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    
    /* Receive Data */
    return (uint16_t)(USARTx->DR & (uint16_t)0x01FF);
  }
  
  /**
    * @}
    */
  
  /** @defgroup USART_Group3 MultiProcessor Communication functions
   *  @brief   Multi-Processor Communication functions 
   *
  @verbatim
   ===============================================================================
               ##### Multi-Processor Communication functions #####
   ===============================================================================
      [..] This subsection provides a set of functions allowing to manage the USART 
           multiprocessor communication.
      [..] For instance one of the USARTs can be the master, its TX output is
           connected to the RX input of the other USART. The others are slaves,
           their respective TX outputs are logically ANDed together and connected 
           to the RX input of the master. USART multiprocessor communication is 
           possible through the following procedure:
           (#) Program the Baud rate, Word length = 9 bits, Stop bits, Parity, 
               Mode transmitter or Mode receiver and hardware flow control values 
               using the USART_Init() function.
           (#) Configures the USART address using the USART_SetAddress() function.
           (#) Configures the wake up methode (USART_WakeUp_IdleLine or 
               USART_WakeUp_AddressMark) using USART_WakeUpConfig() function only 
               for the slaves.
           (#) Enable the USART using the USART_Cmd() function.
           (#) Enter the USART slaves in mute mode using USART_ReceiverWakeUpCmd() 
               function.
  
      [..] The USART Slave exit from mute mode when receive the wake up condition.
  
  @endverbatim
    * @{
    */
  
  /**
    * @brief  Sets the address of the USART node.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  USART_Address: Indicates the address of the USART node.
    * @retval None
    */
  void USART_SetAddress(USART_TypeDef* USARTx, uint8_t USART_Address)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_ADDRESS(USART_Address)); 
      
    /* Clear the USART address */
    USARTx->CR2 &= (uint16_t)~((uint16_t)USART_CR2_ADD);
    /* Set the USART address node */
    USARTx->CR2 |= USART_Address;
  }
  
  /**
    * @brief  Determines if the USART is in mute mode or not.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  NewState: new state of the USART mute mode.
    *   This parameter can be: ENABLE or DISABLE.
    * @retval None
    */
  void USART_ReceiverWakeUpCmd(USART_TypeDef* USARTx, FunctionalState NewState)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_FUNCTIONAL_STATE(NewState)); 
    
    if (NewState != DISABLE)
    {
      /* Enable the USART mute mode  by setting the RWU bit in the CR1 register */
      USARTx->CR1 |= USART_CR1_RWU;
    }
    else
    {
      /* Disable the USART mute mode by clearing the RWU bit in the CR1 register */
      USARTx->CR1 &= (uint16_t)~((uint16_t)USART_CR1_RWU);
    }
  }
  /**
    * @brief  Selects the USART WakeUp method.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  USART_WakeUp: specifies the USART wakeup method.
    *   This parameter can be one of the following values:
    *     @arg USART_WakeUp_IdleLine: WakeUp by an idle line detection.
    *     @arg USART_WakeUp_AddressMark: WakeUp by an address mark.
    * @retval None.
    */
  void USART_WakeUpConfig(USART_TypeDef* USARTx, uint16_t USART_WakeUp)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_WAKEUP(USART_WakeUp));
    
    USARTx->CR1 &= (uint16_t)~((uint16_t)USART_CR1_WAKE);
    USARTx->CR1 |= USART_WakeUp;
  }
  
  /**
    * @}
    */
  
  /** @defgroup USART_Group4 LIN mode functions
   *  @brief   LIN mode functions 
   *
  @verbatim
   ===============================================================================
                         ##### LIN mode functions #####
   ===============================================================================
      [..] This subsection provides a set of functions allowing to manage the USART 
           LIN Mode communication.
      [..] In LIN mode, 8-bit data format with 1 stop bit is required in accordance 
           with the LIN standard.
      [..] Only this LIN Feature is supported by the USART IP:
           (+) LIN Master Synchronous Break send capability and LIN slave break 
               detection capability :  13-bit break generation and 10/11 bit break 
               detection.
      [..] USART LIN Master transmitter communication is possible through the 
           following procedure:
           (#) Program the Baud rate, Word length = 8bits, Stop bits = 1bit, Parity, 
               Mode transmitter or Mode receiver and hardware flow control values 
               using the USART_Init() function.
           (#) Enable the USART using the USART_Cmd() function.
           (#) Enable the LIN mode using the USART_LINCmd() function.
           (#) Send the break character using USART_SendBreak() function.
      [..] USART LIN Master receiver communication is possible through the 
           following procedure:
           (#) Program the Baud rate, Word length = 8bits, Stop bits = 1bit, Parity, 
               Mode transmitter or Mode receiver and hardware flow control values 
              using the USART_Init() function.
           (#) Enable the USART using the USART_Cmd() function.
           (#) Configures the break detection length 
               using the USART_LINBreakDetectLengthConfig() function.
           (#) Enable the LIN mode using the USART_LINCmd() function.
           -@- In LIN mode, the following bits must be kept cleared:
               (+@) CLKEN in the USART_CR2 register.
               (+@) STOP[1:0], SCEN, HDSEL and IREN in the USART_CR3 register.
  
  @endverbatim
    * @{
    */
  
  /**
    * @brief  Sets the USART LIN Break detection length.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  USART_LINBreakDetectLength: specifies the LIN break detection length.
    *   This parameter can be one of the following values:
    *     @arg USART_LINBreakDetectLength_10b: 10-bit break detection.
    *     @arg USART_LINBreakDetectLength_11b: 11-bit break detection.
    * @retval None.
    */
  void USART_LINBreakDetectLengthConfig(USART_TypeDef* USARTx, uint16_t USART_LINBreakDetectLength)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_LIN_BREAK_DETECT_LENGTH(USART_LINBreakDetectLength));
    
    USARTx->CR2 &= (uint16_t)~((uint16_t)USART_CR2_LBDL);
    USARTx->CR2 |= USART_LINBreakDetectLength;  
  }
  
  /**
    * @brief  Enables or disables the USART's LIN mode.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  NewState: new state of the USART LIN mode.
    *   This parameter can be: ENABLE or DISABLE.
    * @retval None.
    */
  void USART_LINCmd(USART_TypeDef* USARTx, FunctionalState NewState)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_FUNCTIONAL_STATE(NewState));
    
    if (NewState != DISABLE)
    {
      /* Enable the LIN mode by setting the LINEN bit in the CR2 register */
      USARTx->CR2 |= USART_CR2_LINEN;
    }
    else
    {
      /* Disable the LIN mode by clearing the LINEN bit in the CR2 register */
      USARTx->CR2 &= (uint16_t)~((uint16_t)USART_CR2_LINEN);
    }
  }
  
  /**
    * @brief  Transmits break characters.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @retval None.
    */
  void USART_SendBreak(USART_TypeDef* USARTx)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    
    /* Send break characters */
    USARTx->CR1 |= USART_CR1_SBK;
  }
  
  /**
    * @}
    */
  
  /** @defgroup USART_Group5 Halfduplex mode function
   *  @brief   Half-duplex mode function 
   *
  @verbatim
   ===============================================================================
                     ##### Half-duplex mode function #####
   ===============================================================================
      [..] This subsection provides a set of functions allowing to manage the USART
           Half-duplex communication.
      [..] The USART can be configured to follow a single-wire half-duplex protocol 
           where the TX and RX lines are internally connected.
      [..] USART Half duplex communication is possible through the following procedure:
           (#) Program the Baud rate, Word length, Stop bits, Parity, Mode transmitter 
               or Mode receiver and hardware flow control values using the USART_Init()
              function.
           (#) Configures the USART address using the USART_SetAddress() function.
           (#) Enable the USART using the USART_Cmd() function.
           (#) Enable the half duplex mode using USART_HalfDuplexCmd() function.
           -@- The RX pin is no longer used.
           -@- In Half-duplex mode the following bits must be kept cleared:
               (+@) LINEN and CLKEN bits in the USART_CR2 register.
               (+@) SCEN and IREN bits in the USART_CR3 register.
  
  @endverbatim
    * @{
    */
  
  /**
    * @brief  Enables or disables the USART's Half Duplex communication.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  NewState: new state of the USART Communication.
    *   This parameter can be: ENABLE or DISABLE.
    * @retval None
    */
  void USART_HalfDuplexCmd(USART_TypeDef* USARTx, FunctionalState NewState)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_FUNCTIONAL_STATE(NewState));
    
    if (NewState != DISABLE)
    {
      /* Enable the Half-Duplex mode by setting the HDSEL bit in the CR3 register */
      USARTx->CR3 |= USART_CR3_HDSEL;
    }
    else
    {
      /* Disable the Half-Duplex mode by clearing the HDSEL bit in the CR3 register */
      USARTx->CR3 &= (uint16_t)~((uint16_t)USART_CR3_HDSEL);
    }
  }
  
  /**
    * @}
    */
  
  
  /** @defgroup USART_Group6 Smartcard mode functions
   *  @brief   Smartcard mode functions 
   *
  @verbatim
   ===============================================================================
                       ##### Smartcard mode functions #####
   ===============================================================================
      [..] This subsection provides a set of functions allowing to manage the USART 
           Smartcard communication.
      [..] The Smartcard interface is designed to support asynchronous protocol 
           Smartcards as defined in the ISO 7816-3 standard. The USART can provide 
           a clock to the smartcard through the SCLK output. In smartcard mode, 
           SCLK is not associated to the communication but is simply derived from 
           the internal peripheral input clock through a 5-bit prescaler.
      [..] Smartcard communication is possible through the following procedure:
           (#) Configures the Smartcard Prsecaler using the USART_SetPrescaler() 
               function.
           (#) Configures the Smartcard Guard Time using the USART_SetGuardTime() 
               function.
           (#) Program the USART clock using the USART_ClockInit() function as following:
               (++) USART Clock enabled.
               (++) USART CPOL Low.
               (++) USART CPHA on first edge.
               (++) USART Last Bit Clock Enabled.
           (#) Program the Smartcard interface using the USART_Init() function as 
               following:
               (++) Word Length = 9 Bits.
               (++) 1.5 Stop Bit.
               (++) Even parity.
               (++) BaudRate = 12096 baud.
               (++) Hardware flow control disabled (RTS and CTS signals).
               (++) Tx and Rx enabled
           (#) Optionally you can enable the parity error interrupt using 
               the USART_ITConfig() function.
           (#) Enable the USART using the USART_Cmd() function.
           (#) Enable the Smartcard NACK using the USART_SmartCardNACKCmd() function.
           (#) Enable the Smartcard interface using the USART_SmartCardCmd() function.
      [..] 
    Please refer to the ISO 7816-3 specification for more details.
      [..] 
           (@) It is also possible to choose 0.5 stop bit for receiving but it is 
               recommended to use 1.5 stop bits for both transmitting and receiving 
               to avoid switching between the two configurations.
           (@) In smartcard mode, the following bits must be kept cleared:
               (+@) LINEN bit in the USART_CR2 register.
               (+@) HDSEL and IREN bits in the USART_CR3 register.
  
  @endverbatim
    * @{
    */
  
  /**
    * @brief  Sets the specified USART guard time.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2 or USART3.
    * @param  USART_GuardTime: specifies the guard time.   
    * @retval None.
    */
  void USART_SetGuardTime(USART_TypeDef* USARTx, uint8_t USART_GuardTime)
  {    
    /* Check the parameters */
    assert_param(IS_USART_123_PERIPH(USARTx));
    
    /* Clear the USART Guard time */
    USARTx->GTPR &= USART_GTPR_PSC;
    /* Set the USART guard time */
    USARTx->GTPR |= (uint16_t)((uint16_t)USART_GuardTime << 0x08);
  }
  
  /**
    * @brief  Enables or disables the USART's Smart Card mode.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2 or USART3.
    * @param  NewState: new state of the Smart Card mode.
    *   This parameter can be: ENABLE or DISABLE.      
    * @retval None
    */
  void USART_SmartCardCmd(USART_TypeDef* USARTx, FunctionalState NewState)
  {
    /* Check the parameters */
    assert_param(IS_USART_123_PERIPH(USARTx));
    assert_param(IS_FUNCTIONAL_STATE(NewState));
    if (NewState != DISABLE)
    {
      /* Enable the SC mode by setting the SCEN bit in the CR3 register */
      USARTx->CR3 |= USART_CR3_SCEN;
    }
    else
    {
      /* Disable the SC mode by clearing the SCEN bit in the CR3 register */
      USARTx->CR3 &= (uint16_t)~((uint16_t)USART_CR3_SCEN);
    }
  }
  
  /**
    * @brief  Enables or disables NACK transmission.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2 or USART3.
    * @param  NewState: new state of the NACK transmission.
    *   This parameter can be: ENABLE or DISABLE.  
    * @retval None.
    */
  void USART_SmartCardNACKCmd(USART_TypeDef* USARTx, FunctionalState NewState)
  {
    /* Check the parameters */
    assert_param(IS_USART_123_PERIPH(USARTx)); 
    assert_param(IS_FUNCTIONAL_STATE(NewState));
    if (NewState != DISABLE)
    {
      /* Enable the NACK transmission by setting the NACK bit in the CR3 register */
      USARTx->CR3 |= USART_CR3_NACK;
    }
    else
    {
      /* Disable the NACK transmission by clearing the NACK bit in the CR3 register */
      USARTx->CR3 &= (uint16_t)~((uint16_t)USART_CR3_NACK);
    }
  }
  
  /**
    * @}
    */
  
  /** @defgroup USART_Group7 IrDA mode functions
   *  @brief   IrDA mode functions 
   *
  @verbatim
   ===============================================================================
                          ##### IrDA mode functions #####
   ===============================================================================
      [..] This subsection provides a set of functions allowing to manage the USART 
           IrDA communication.
      [..] IrDA is a half duplex communication protocol. If the Transmitter is busy, 
           any data on the IrDA receive line will be ignored by the IrDA decoder 
           and if the Receiver is busy, data on the TX from the USART to IrDA will 
           not be encoded by IrDA. While receiving data, transmission should be 
           avoided as the data to be transmitted could be corrupted.
  
      [..] IrDA communication is possible through the following procedure:
           (#) Program the Baud rate, Word length = 8 bits, Stop bits, Parity, 
               Transmitter/Receiver modes and hardware flow control values using 
               the USART_Init() function.
           (#) Enable the USART using the USART_Cmd() function.
           (#) Configures the IrDA pulse width by configuring the prescaler using  
               the USART_SetPrescaler() function.
           (#) Configures the IrDA  USART_IrDAMode_LowPower or USART_IrDAMode_Normal 
               mode using the USART_IrDAConfig() function.
           (#) Enable the IrDA using the USART_IrDACmd() function.
  
      [..]
      (@) A pulse of width less than two and greater than one PSC period(s) may or 
          may not be rejected.
      (@) The receiver set up time should be managed by software. The IrDA physical 
          layer specification specifies a minimum of 10 ms delay between 
          transmission and reception (IrDA is a half duplex protocol).
      (@) In IrDA mode, the following bits must be kept cleared:
          (+@) LINEN, STOP and CLKEN bits in the USART_CR2 register.
          (+@) SCEN and HDSEL bits in the USART_CR3 register.
  
  @endverbatim
    * @{
    */
  
  /**
    * @brief  Configures the USART's IrDA interface.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  USART_IrDAMode: specifies the IrDA mode.
    *   This parameter can be one of the following values:
    *     @arg USART_IrDAMode_LowPower: USART IrDA Low Power mode selected.
    *     @arg USART_IrDAMode_Normal: USART IrDA Normal mode selected.
    * @retval None
    */
  void USART_IrDAConfig(USART_TypeDef* USARTx, uint16_t USART_IrDAMode)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_IRDA_MODE(USART_IrDAMode));
      
    USARTx->CR3 &= (uint16_t)~((uint16_t)USART_CR3_IRLP);
    USARTx->CR3 |= USART_IrDAMode;
  }
  
  /**
    * @brief  Enables or disables the USART's IrDA interface.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  NewState: new state of the IrDA mode.
    *   This parameter can be: ENABLE or DISABLE.
    * @retval None
    */
  void USART_IrDACmd(USART_TypeDef* USARTx, FunctionalState NewState)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_FUNCTIONAL_STATE(NewState));
      
    if (NewState != DISABLE)
    {
      /* Enable the IrDA mode by setting the IREN bit in the CR3 register */
      USARTx->CR3 |= USART_CR3_IREN;
    }
    else
    {
      /* Disable the IrDA mode by clearing the IREN bit in the CR3 register */
      USARTx->CR3 &= (uint16_t)~((uint16_t)USART_CR3_IREN);
    }
  }
  
  /**
    * @}
    */
  
  /** @defgroup USART_Group8 DMA transfers management functions
   *  @brief   DMA transfers management functions
   *
  @verbatim
   ===============================================================================
                 ##### DMA transfers management functions #####
   ===============================================================================
  
  @endverbatim
    * @{
    */
    
  /**
    * @brief  Enables or disables the USART's DMA interface.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  USART_DMAReq: specifies the DMA request.
    *   This parameter can be any combination of the following values:
    *     @arg USART_DMAReq_Tx: USART DMA transmit request.
    *     @arg USART_DMAReq_Rx: USART DMA receive request.
    * @param  NewState: new state of the DMA Request sources.
    *   This parameter can be: ENABLE or DISABLE.   
    * @retval None
    */
  void USART_DMACmd(USART_TypeDef* USARTx, uint16_t USART_DMAReq, FunctionalState NewState)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_DMAREQ(USART_DMAReq));  
    assert_param(IS_FUNCTIONAL_STATE(NewState)); 
  
    if (NewState != DISABLE)
    {
      /* Enable the DMA transfer for selected requests by setting the DMAT and/or
         DMAR bits in the USART CR3 register */
      USARTx->CR3 |= USART_DMAReq;
    }
    else
    {
      /* Disable the DMA transfer for selected requests by clearing the DMAT and/or
         DMAR bits in the USART CR3 register */
      USARTx->CR3 &= (uint16_t)~USART_DMAReq;
    }
  }
  
  /**
    * @}
    */
    
  /** @defgroup USART_Group9 Interrupts and flags management functions
   *  @brief   Interrupts and flags management functions 
   *
  @verbatim
   ===============================================================================
              ##### Interrupts and flags management functions #####
   ===============================================================================
      [..] This subsection provides a set of functions allowing to configure the 
           USART Interrupts sources, DMA channels requests and check or clear the 
           flags or pending bits status. The user should identify which mode will 
           be used in his application to manage the communication: Polling mode, 
           Interrupt mode or DMA mode.
   *** Polling Mode ***
   ====================
      [..] In Polling Mode, the SPI communication can be managed by 10 flags:
           (#) USART_FLAG_TXE: to indicate the status of the transmit buffer register.
           (#) USART_FLAG_RXNE: to indicate the status of the receive buffer register.
           (#) USART_FLAG_TC: to indicate the status of the transmit operation.
           (#) USART_FLAG_IDLE: to indicate the status of the Idle Line.
           (#) USART_FLAG_CTS: to indicate the status of the nCTS input.
           (#) USART_FLAG_LBD: to indicate the status of the LIN break detection.
           (#) USART_FLAG_NE: to indicate if a noise error occur.
           (#) USART_FLAG_FE: to indicate if a frame error occur.
           (#) USART_FLAG_PE: to indicate if a parity error occur.
           (#) USART_FLAG_ORE: to indicate if an Overrun error occur.
      [..] In this Mode it is advised to use the following functions:
           (+) FlagStatus USART_GetFlagStatus(USART_TypeDef* USARTx, uint16_t USART_FLAG).
           (+) void USART_ClearFlag(USART_TypeDef* USARTx, uint16_t USART_FLAG).
    
   *** Interrupt Mode ***
   ======================
      [..] In Interrupt Mode, the USART communication can be managed by 8 interrupt 
           sources and 10 pending bits:
           (+) Pending Bits:
               (##) USART_IT_TXE: to indicate the status of the transmit buffer 
                    register.
               (##) USART_IT_RXNE: to indicate the status of the receive buffer 
                    register.
               (##) USART_IT_TC: to indicate the status of the transmit operation.
               (##) USART_IT_IDLE: to indicate the status of the Idle Line.
               (##) USART_IT_CTS: to indicate the status of the nCTS input.
               (##) USART_IT_LBD: to indicate the status of the LIN break detection.
               (##) USART_IT_NE: to indicate if a noise error occur.
               (##) USART_IT_FE: to indicate if a frame error occur.
               (##) USART_IT_PE: to indicate if a parity error occur.
               (##) USART_IT_ORE: to indicate if an Overrun error occur
                    (if the RXNEIE or EIE bits are set).
  
           (+) Interrupt Source:
               (##) USART_IT_TXE: specifies the interrupt source for the Tx buffer 
                    empty interrupt. 
               (##) USART_IT_RXNE: specifies the interrupt source for the Rx buffer 
                    not empty interrupt.
               (##) USART_IT_TC: specifies the interrupt source for the Transmit 
                    complete interrupt. 
               (##) USART_IT_IDLE: specifies the interrupt source for the Idle Line 
                    interrupt.
               (##) USART_IT_CTS: specifies the interrupt source for the CTS interrupt. 
               (##) USART_IT_LBD: specifies the interrupt source for the LIN break 
                    detection interrupt. 
               (##) USART_IT_PE: specifies the interrupt source for theparity error 
                    interrupt. 
               (##) USART_IT_ERR:  specifies the interrupt source for the errors 
                    interrupt.
               -@@- Some parameters are coded in order to use them as interrupt 
                   source or as pending bits.
      [..] In this Mode it is advised to use the following functions:
           (+) void USART_ITConfig(USART_TypeDef* USARTx, uint16_t USART_IT, 
               FunctionalState NewState).
           (+) ITStatus USART_GetITStatus(USART_TypeDef* USARTx, uint16_t USART_IT).
           (+) void USART_ClearITPendingBit(USART_TypeDef* USARTx, uint16_t USART_IT).
    
   *** DMA Mode ***
   ================
      [..] In DMA Mode, the USART communication can be managed by 2 DMA Channel 
           requests:
           (#) USART_DMAReq_Tx: specifies the Tx buffer DMA transfer request.
           (#) USART_DMAReq_Rx: specifies the Rx buffer DMA transfer request.
      [..] In this Mode it is advised to use the following function:
           (+) void USART_DMACmd(USART_TypeDef* USARTx, uint16_t USART_DMAReq, 
               FunctionalState NewState).
  @endverbatim
    * @{
    */
  
  /**
    * @brief  Enables or disables the specified USART interrupts.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  USART_IT: specifies the USART interrupt sources to be enabled or disabled.
    *   This parameter can be one of the following values:
    *     @arg USART_IT_CTS:  CTS change interrupt.
    *     @arg USART_IT_LBD:  LIN Break detection interrupt.
    *     @arg USART_IT_TXE:  Tansmit Data Register empty interrupt.
    *     @arg USART_IT_TC:   Transmission complete interrupt.
    *     @arg USART_IT_RXNE: Receive Data register not empty interrupt.
    *     @arg USART_IT_IDLE: Idle line detection interrupt.
    *     @arg USART_IT_PE:   Parity Error interrupt.
    *     @arg USART_IT_ERR:  Error interrupt(Frame error, noise error, overrun error).
    * @param  NewState: new state of the specified USARTx interrupts.
    *   This parameter can be: ENABLE or DISABLE.
    * @retval None.
    */
  void USART_ITConfig(USART_TypeDef* USARTx, uint16_t USART_IT, FunctionalState NewState)
  {
    uint32_t usartreg = 0x00, itpos = 0x00, itmask = 0x00;
    uint32_t usartxbase = 0x00;
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_CONFIG_IT(USART_IT));
    assert_param(IS_FUNCTIONAL_STATE(NewState));
  
    /* The CTS interrupt is not available for UART4 and UART5 */
    if (USART_IT == USART_IT_CTS)
    {
      assert_param(IS_USART_123_PERIPH(USARTx));
    } 
      
    usartxbase = (uint32_t)USARTx;
  
    /* Get the USART register index */
    usartreg = (((uint8_t)USART_IT) >> 0x05);
  
    /* Get the interrupt position */
    itpos = USART_IT & IT_MASK;
    itmask = (((uint32_t)0x01) << itpos);
      
    if (usartreg == 0x01) /* The IT is in CR1 register */
    {
      usartxbase += 0x0C;
    }
    else if (usartreg == 0x02) /* The IT is in CR2 register */
    {
      usartxbase += 0x10;
    }
    else /* The IT is in CR3 register */
    {
      usartxbase += 0x14; 
    }
    if (NewState != DISABLE)
    {
      *(__IO uint32_t*)usartxbase  |= itmask;
    }
    else
    {
      *(__IO uint32_t*)usartxbase &= ~itmask;
    }
  }
  
  /**
    * @brief  Checks whether the specified USART flag is set or not.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  USART_FLAG: specifies the flag to check.
    *   This parameter can be one of the following values:
    *     @arg USART_FLAG_CTS:  CTS Change flag (not available for UART4 and UART5).
    *     @arg USART_FLAG_LBD:  LIN Break detection flag.
    *     @arg USART_FLAG_TXE:  Transmit data register empty flag.
    *     @arg USART_FLAG_TC:   Transmission Complete flag.
    *     @arg USART_FLAG_RXNE: Receive data register not empty flag.
    *     @arg USART_FLAG_IDLE: Idle Line detection flag.
    *     @arg USART_FLAG_ORE:  OverRun Error flag.
    *     @arg USART_FLAG_NE:   Noise Error flag.
    *     @arg USART_FLAG_FE:   Framing Error flag.
    *     @arg USART_FLAG_PE:   Parity Error flag.
    * @retval The new state of USART_FLAG (SET or RESET).
    */
  FlagStatus USART_GetFlagStatus(USART_TypeDef* USARTx, uint16_t USART_FLAG)
  {
    FlagStatus bitstatus = RESET;
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_FLAG(USART_FLAG));
  
    /* The CTS flag is not available for UART4 and UART5 */
    if (USART_FLAG == USART_FLAG_CTS)
    {
      assert_param(IS_USART_123_PERIPH(USARTx));
    } 
      
    if ((USARTx->SR & USART_FLAG) != (uint16_t)RESET)
    {
      bitstatus = SET;
    }
    else
    {
      bitstatus = RESET;
    }
    return bitstatus;
  }
  
  /**
    * @brief  Clears the USARTx's pending flags.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  USART_FLAG: specifies the flag to clear.
    *   This parameter can be any combination of the following values:
    *     @arg USART_FLAG_CTS:  CTS Change flag (not available for UART4 and UART5).
    *     @arg USART_FLAG_LBD:  LIN Break detection flag.
    *     @arg USART_FLAG_TC:   Transmission Complete flag.
    *     @arg USART_FLAG_RXNE: Receive data register not empty flag.
    *   
    *
    * @note PE (Parity error), FE (Framing error), NE (Noise error), ORE (OverRun 
    *     error) and IDLE (Idle line detected) flags are cleared by software 
    *     sequence: a read operation to USART_SR register (USART_GetFlagStatus()) 
    *     followed by a read operation to USART_DR register (USART_ReceiveData()).
    * @note RXNE flag can be also cleared by a read to the USART_DR register 
    *     (USART_ReceiveData()).
    * @note TC flag can be also cleared by software sequence: a read operation to 
    *     USART_SR register (USART_GetFlagStatus()) followed by a write operation
    *     to USART_DR register (USART_SendData()).
    * @note TXE flag is cleared only by a write to the USART_DR register 
    *     (USART_SendData()).
    * @retval None
    */
  void USART_ClearFlag(USART_TypeDef* USARTx, uint16_t USART_FLAG)
  {
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_CLEAR_FLAG(USART_FLAG));
  
    /* The CTS flag is not available for UART4 and UART5 */
    if ((USART_FLAG & USART_FLAG_CTS) == USART_FLAG_CTS)
    {
      assert_param(IS_USART_123_PERIPH(USARTx));
    } 
         
    USARTx->SR = (uint16_t)~USART_FLAG;
  }
  
  /**
    * @brief  Checks whether the specified USART interrupt has occurred or not.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  USART_IT: specifies the USART interrupt source to check.
    *   This parameter can be one of the following values:
    *     @arg USART_IT_CTS:  CTS change interrupt (not available for UART4 and UART5)
    *     @arg USART_IT_LBD:  LIN Break detection interrupt
    *     @arg USART_IT_TXE:  Tansmit Data Register empty interrupt
    *     @arg USART_IT_TC:   Transmission complete interrupt
    *     @arg USART_IT_RXNE: Receive Data register not empty interrupt
    *     @arg USART_IT_IDLE: Idle line detection interrupt
    *     @arg USART_IT_ORE_RX: OverRun Error interrupt if the RXNEIE bit is set.
    *     @arg USART_IT_ORE_ER: OverRun Error interrupt if the EIE bit is set.   
    *     @arg USART_IT_NE:   Noise Error interrupt
    *     @arg USART_IT_FE:   Framing Error interrupt
    *     @arg USART_IT_PE:   Parity Error interrupt
    * @retval The new state of USART_IT (SET or RESET).
    */
  ITStatus USART_GetITStatus(USART_TypeDef* USARTx, uint16_t USART_IT)
  {
    uint32_t bitpos = 0x00, itmask = 0x00, usartreg = 0x00;
    ITStatus bitstatus = RESET;
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_GET_IT(USART_IT)); 
  
    /* The CTS interrupt is not available for UART4 and UART5 */ 
    if (USART_IT == USART_IT_CTS)
    {
      assert_param(IS_USART_123_PERIPH(USARTx));
    } 
      
    /* Get the USART register index */
    usartreg = (((uint8_t)USART_IT) >> 0x05);
    /* Get the interrupt position */
    itmask = USART_IT & IT_MASK;
    itmask = (uint32_t)0x01 << itmask;
    
    if (usartreg == 0x01) /* The IT  is in CR1 register */
    {
      itmask &= USARTx->CR1;
    }
    else if (usartreg == 0x02) /* The IT  is in CR2 register */
    {
      itmask &= USARTx->CR2;
    }
    else /* The IT  is in CR3 register */
    {
      itmask &= USARTx->CR3;
    }
    
    bitpos = USART_IT >> 0x08;
    bitpos = (uint32_t)0x01 << bitpos;
    bitpos &= USARTx->SR;
    if ((itmask != (uint16_t)RESET)&&(bitpos != (uint16_t)RESET))
    {
      bitstatus = SET;
    }
    else
    {
      bitstatus = RESET;
    }
    
    return bitstatus;  
  }
  
  /**
    * @brief  Clears the USARTx's interrupt pending bits.
    * @param  USARTx: Select the USART peripheral. 
    *   This parameter can be one of the following values:
    *   USART1, USART2, USART3, UART4 or UART5.
    * @param  USART_IT: specifies the interrupt pending bit to clear.
    *   This parameter can be one of the following values:
    *     @arg USART_IT_CTS:  CTS change interrupt (not available for UART4 and UART5)
    *     @arg USART_IT_LBD:  LIN Break detection interrupt
    *     @arg USART_IT_TC:   Transmission complete interrupt. 
    *     @arg USART_IT_RXNE: Receive Data register not empty interrupt.
    *   
  
    * @note PE (Parity error), FE (Framing error), NE (Noise error), ORE (OverRun 
    *     error) and IDLE (Idle line detected) pending bits are cleared by 
    *     software sequence: a read operation to USART_SR register 
    *     (USART_GetITStatus()) followed by a read operation to USART_DR register 
    *     (USART_ReceiveData()).
    * @note RXNE pending bit can be also cleared by a read to the USART_DR register 
    *     (USART_ReceiveData()).
    * @note TC pending bit can be also cleared by software sequence: a read 
    *     operation to USART_SR register (USART_GetITStatus()) followed by a write 
    *     operation to USART_DR register (USART_SendData()).
    * @note TXE pending bit is cleared only by a write to the USART_DR register 
    *     (USART_SendData()).
    * @retval None
    */
  void USART_ClearITPendingBit(USART_TypeDef* USARTx, uint16_t USART_IT)
  {
    uint16_t bitpos = 0x00, itmask = 0x00;
    /* Check the parameters */
    assert_param(IS_USART_ALL_PERIPH(USARTx));
    assert_param(IS_USART_CLEAR_IT(USART_IT)); 
  
    /* The CTS interrupt is not available for UART4 and UART5 */
    if (USART_IT == USART_IT_CTS)
    {
      assert_param(IS_USART_123_PERIPH(USARTx));
    } 
      
    bitpos = USART_IT >> 0x08;
    itmask = ((uint16_t)0x01 << (uint16_t)bitpos);
    USARTx->SR = (uint16_t)~itmask;
  }
  
  /**
    * @}
    */
  
  /**
    * @}
    */
  
  /**
    * @}
    */
  
  /**
    * @}
    */
  
  /******************* (C) COPYRIGHT 2012 STMicroelectronics *****END OF FILE****/
  