/**
  ******************************************************************************
  * @file    stm32l1xx_wwdg.c
  * @author  MCD Application Team
  * @version V1.2.0
  * @date    22-February-2013
  * @brief   This file provides firmware functions to manage the following 
  *          functionalities of the Window watchdog (WWDG) peripheral:           
  *           + Prescaler, Refresh window and Counter configuration
  *           + WWDG activation
  *           + Interrupts and flags management
  *             
  *  @verbatim
  *    
  ============================================================================== 
                           ##### WWDG features ##### 
  ============================================================================== 
    [..] Once enabled the WWDG generates a system reset on expiry of a programmed
        time period, unless the program refreshes the counter (downcounter) 
        before to reach 0x3F value (i.e. a reset is generated when the counter
        value rolls over from 0x40 to 0x3F). 
    [..] An MCU reset is also generated if the counter value is refreshed
         before the counter has reached the refresh window value. This 
         implies that the counter must be refreshed in a limited window.

    [..] Once enabled the WWDG cannot be disabled except by a system reset.

    [..] WWDGRST flag in RCC_CSR register can be used to inform when a WWDG
         reset occurs.

    [..] The WWDG counter input clock is derived from the APB clock divided 
         by a programmable prescaler.

    [..] WWDG counter clock = PCLK1 / Prescaler.
    [..] WWDG timeout = (WWDG counter clock) * (counter value).

    [..] Min-max timeout value @32MHz (PCLK1): ~128us / ~65.6ms.

                       ##### How to use this driver ##### 
  ==============================================================================
    [..]
        (#) Enable WWDG clock using RCC_APB1PeriphClockCmd(RCC_APB1Periph_WWDG, ENABLE) 
            function.
              
        (#) Configure the WWDG prescaler using WWDG_SetPrescaler() function.
                             
        (#) Configure the WWDG refresh window using WWDG_SetWindowValue() function.
              
        (#) Set the WWDG counter value and start it using WWDG_Enable() function.
            When the WWDG is enabled the counter value should be configured to 
            a value greater than 0x40 to prevent generating an immediate reset.
              
        (#) Optionally you can enable the Early wakeup interrupt which is 
            generated when the counter reach 0x40.
            Once enabled this interrupt cannot be disabled except by a system reset.
                   
        (#) Then the application program must refresh the WWDG counter at regular
            intervals during normal operation to prevent an MCU reset, using
            WWDG_SetCounter() function. This operation must occur only when
            the counter value is lower than the refresh window value, 
            programmed using WWDG_SetWindowValue().
  
  *  @endverbatim  
  *                             
  ******************************************************************************
  * @attention
  *
  * <h2><center>&copy; COPYRIGHT 2013 STMicroelectronics</center></h2>
  *
  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *        http://www.st.com/software_license_agreement_liberty_v2
  *
  * Unless required by applicable law or agreed to in writing, software 
  * distributed under the License is distributed on an "AS IS" BASIS, 
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  ******************************************************************************
  */

/* Includes ------------------------------------------------------------------*/
#include "stm32l1xx_wwdg.h"
#include "stm32l1xx_rcc.h"

/** @addtogroup STM32L1xx_StdPeriph_Driver
  * @{
  */

/** @defgroup WWDG 
  * @brief WWDG driver modules
  * @{
  */

/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/

/* ----------- WWDG registers bit address in the alias region ----------- */
#define WWDG_OFFSET       (WWDG_BASE - PERIPH_BASE)

/* Alias word address of EWI bit */
#define CFR_OFFSET        (WWDG_OFFSET + 0x04)
#define EWI_BitNumber     0x09
#define CFR_EWI_BB        (PERIPH_BB_BASE + (CFR_OFFSET * 32) + (EWI_BitNumber * 4))

/* --------------------- WWDG registers bit mask ------------------------ */

/* CFR register bit mask */
#define CFR_WDGTB_MASK    ((uint32_t)0xFFFFFE7F)
#define CFR_W_MASK        ((uint32_t)0xFFFFFF80)
#define BIT_MASK          ((uint8_t)0x7F)

/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
/* Private function prototypes -----------------------------------------------*/
/* Private functions ---------------------------------------------------------*/

/** @defgroup WWDG_Private_Functions
  * @{
  */

/** @defgroup WWDG_Group1 Prescaler, Refresh window and Counter configuration functions
 *  @brief   Prescaler, Refresh window and Counter configuration functions 
 *
@verbatim   
  ==============================================================================
    ##### Prescaler, Refresh window and Counter configuration functions #####
  ==============================================================================  

@endverbatim
  * @{
  */

/**
  * @brief  Deinitializes the WWDG peripheral registers to their default reset values.
  * @param  None
  * @retval None
  */
void WWDG_DeInit(void)
{
  RCC_APB1PeriphResetCmd(RCC_APB1Periph_WWDG, ENABLE);
  RCC_APB1PeriphResetCmd(RCC_APB1Periph_WWDG, DISABLE);
}

/**
  * @brief  Sets the WWDG Prescaler.
  * @param  WWDG_Prescaler: specifies the WWDG Prescaler.
  *   This parameter can be one of the following values:
  *     @arg WWDG_Prescaler_1: WWDG counter clock = (PCLK1/4096)/1
  *     @arg WWDG_Prescaler_2: WWDG counter clock = (PCLK1/4096)/2
  *     @arg WWDG_Prescaler_4: WWDG counter clock = (PCLK1/4096)/4
  *     @arg WWDG_Prescaler_8: WWDG counter clock = (PCLK1/4096)/8
  * @retval None
  */
void WWDG_SetPrescaler(uint32_t WWDG_Prescaler)
{
  uint32_t tmpreg = 0;
  /* Check the parameters */
  assert_param(IS_WWDG_PRESCALER(WWDG_Prescaler));
  /* Clear WDGTB[1:0] bits */
  tmpreg = WWDG->CFR & CFR_WDGTB_MASK;
  /* Set WDGTB[1:0] bits according to WWDG_Prescaler value */
  tmpreg |= WWDG_Prescaler;
  /* Store the new value */
  WWDG->CFR = tmpreg;
}

/**
  * @brief  Sets the WWDG window value.
  * @param  WindowValue: specifies the window value to be compared to the downcounter.
  *   This parameter value must be lower than 0x80.
  * @retval None
  */
void WWDG_SetWindowValue(uint8_t WindowValue)
{
  __IO uint32_t tmpreg = 0;

  /* Check the parameters */
  assert_param(IS_WWDG_WINDOW_VALUE(WindowValue));
  /* Clear W[6:0] bits */

  tmpreg = WWDG->CFR & CFR_W_MASK;

  /* Set W[6:0] bits according to WindowValue value */
  tmpreg |= WindowValue & (uint32_t) BIT_MASK;

  /* Store the new value */
  WWDG->CFR = tmpreg;
}

/**
  * @brief  Enables the WWDG Early Wakeup interrupt(EWI).
  * @note   Once enabled this interrupt cannot be disabled except by a system reset. 
  * @param  None
  * @retval None
  */
void WWDG_EnableIT(void)
{
  *(__IO uint32_t *) CFR_EWI_BB = (uint32_t)ENABLE;
}

/**
  * @brief  Sets the WWDG counter value.
  * @param  Counter: specifies the watchdog counter value.
  *   This parameter must be a number between 0x40 and 0x7F (to prevent generating
  *   an immediate reset).
  * @retval None
  */
void WWDG_SetCounter(uint8_t Counter)
{
  /* Check the parameters */
  assert_param(IS_WWDG_COUNTER(Counter));
  /* Write to T[6:0] bits to configure the counter value, no need to do
     a read-modify-write; writing a 0 to WDGA bit does nothing */
  WWDG->CR = Counter & BIT_MASK;
}

/**
  * @}
  */

/** @defgroup WWDG_Group2 WWDG activation functions
 *  @brief   WWDG activation functions 
 *
@verbatim   
  ==============================================================================
                     ##### WWDG activation function #####
  ==============================================================================  

@endverbatim
  * @{
  */

/**
  * @brief  Enables WWDG and load the counter value.                  
  * @param  Counter: specifies the watchdog counter value.
  *   This parameter must be a number between 0x40 and 0x7F (to prevent generating
  *   an immediate reset).
  * @retval None
  */
void WWDG_Enable(uint8_t Counter)
{
  /* Check the parameters */
  assert_param(IS_WWDG_COUNTER(Counter));
  WWDG->CR = WWDG_CR_WDGA | Counter;
}

/**
  * @}
  */

/** @defgroup WWDG_Group3 Interrupts and flags management functions
 *  @brief   Interrupts and flags management functions 
 *
@verbatim   
  ==============================================================================
                ##### Interrupts and flags management functions #####
  ==============================================================================  

@endverbatim
  * @{
  */

/**
  * @brief  Checks whether the Early Wakeup interrupt flag is set or not.
  * @param  None
  * @retval The new state of the Early Wakeup interrupt flag (SET or RESET).
  */
FlagStatus WWDG_GetFlagStatus(void)
{
  FlagStatus bitstatus = RESET;
    
  if ((WWDG->SR) != (uint32_t)RESET)
  {
    bitstatus = SET;
  }
  else
  {
    bitstatus = RESET;
  }
  return bitstatus;
}

/**
  * @brief  Clears Early Wakeup interrupt flag.
  * @param  None
  * @retval None
  */
void WWDG_ClearFlag(void)
{
  WWDG->SR = (uint32_t)RESET;
}

/**
  * @}
  */

/**
  * @}
  */

/**
  * @}
  */

/**
  * @}
  */

/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
