/**
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******************************************************************************
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* @file stm32l1xx_wwdg.c
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* @author MCD Application Team
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* @version V1.3.1
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* @date 20-April-2015
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* @brief This file provides firmware functions to manage the following
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* functionalities of the Window watchdog (WWDG) peripheral:
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* + Prescaler, Refresh window and Counter configuration
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* + WWDG activation
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* + Interrupts and flags management
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*
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* @verbatim
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*
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==============================================================================
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##### WWDG features #####
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==============================================================================
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[..] Once enabled the WWDG generates a system reset on expiry of a programmed
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time period, unless the program refreshes the counter (downcounter)
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before to reach 0x3F value (i.e. a reset is generated when the counter
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value rolls over from 0x40 to 0x3F).
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[..] An MCU reset is also generated if the counter value is refreshed
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before the counter has reached the refresh window value. This
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implies that the counter must be refreshed in a limited window.
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[..] Once enabled the WWDG cannot be disabled except by a system reset.
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[..] WWDGRST flag in RCC_CSR register can be used to inform when a WWDG
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reset occurs.
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[..] The WWDG counter input clock is derived from the APB clock divided
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by a programmable prescaler.
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[..] WWDG counter clock = PCLK1 / Prescaler.
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[..] WWDG timeout = (WWDG counter clock) * (counter value).
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[..] Min-max timeout value @32MHz (PCLK1): ~128us / ~65.6ms.
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##### How to use this driver #####
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==============================================================================
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[..]
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(#) Enable WWDG clock using RCC_APB1PeriphClockCmd(RCC_APB1Periph_WWDG, ENABLE)
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function.
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(#) Configure the WWDG prescaler using WWDG_SetPrescaler() function.
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(#) Configure the WWDG refresh window using WWDG_SetWindowValue() function.
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(#) Set the WWDG counter value and start it using WWDG_Enable() function.
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When the WWDG is enabled the counter value should be configured to
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a value greater than 0x40 to prevent generating an immediate reset.
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(#) Optionally you can enable the Early wakeup interrupt which is
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generated when the counter reach 0x40.
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Once enabled this interrupt cannot be disabled except by a system reset.
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(#) Then the application program must refresh the WWDG counter at regular
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intervals during normal operation to prevent an MCU reset, using
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WWDG_SetCounter() function. This operation must occur only when
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the counter value is lower than the refresh window value,
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programmed using WWDG_SetWindowValue().
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* @endverbatim
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*
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******************************************************************************
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* @attention
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*
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* <h2><center>© COPYRIGHT 2015 STMicroelectronics</center></h2>
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*
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* Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
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* You may not use this file except in compliance with the License.
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* You may obtain a copy of the License at:
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*
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* http://www.st.com/software_license_agreement_liberty_v2
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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******************************************************************************
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*/
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/* Includes ------------------------------------------------------------------*/
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#include "stm32l1xx_wwdg.h"
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#include "stm32l1xx_rcc.h"
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/** @addtogroup STM32L1xx_StdPeriph_Driver
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* @{
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*/
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/** @defgroup WWDG
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* @brief WWDG driver modules
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* @{
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*/
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/* Private typedef -----------------------------------------------------------*/
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/* Private define ------------------------------------------------------------*/
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/* ----------- WWDG registers bit address in the alias region ----------- */
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#define WWDG_OFFSET (WWDG_BASE - PERIPH_BASE)
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/* Alias word address of EWI bit */
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#define CFR_OFFSET (WWDG_OFFSET + 0x04)
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#define EWI_BitNumber 0x09
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#define CFR_EWI_BB (PERIPH_BB_BASE + (CFR_OFFSET * 32) + (EWI_BitNumber * 4))
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/* --------------------- WWDG registers bit mask ------------------------ */
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/* CFR register bit mask */
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#define CFR_WDGTB_MASK ((uint32_t)0xFFFFFE7F)
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#define CFR_W_MASK ((uint32_t)0xFFFFFF80)
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#define BIT_MASK ((uint8_t)0x7F)
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/* Private macro -------------------------------------------------------------*/
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/* Private variables ---------------------------------------------------------*/
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/* Private function prototypes -----------------------------------------------*/
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/* Private functions ---------------------------------------------------------*/
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/** @defgroup WWDG_Private_Functions
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* @{
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*/
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/** @defgroup WWDG_Group1 Prescaler, Refresh window and Counter configuration functions
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* @brief Prescaler, Refresh window and Counter configuration functions
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*
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@verbatim
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==============================================================================
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##### Prescaler, Refresh window and Counter configuration functions #####
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==============================================================================
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@endverbatim
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* @{
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*/
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/**
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* @brief Deinitializes the WWDG peripheral registers to their default reset values.
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* @param None
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* @retval None
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*/
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void WWDG_DeInit(void)
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{
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RCC_APB1PeriphResetCmd(RCC_APB1Periph_WWDG, ENABLE);
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RCC_APB1PeriphResetCmd(RCC_APB1Periph_WWDG, DISABLE);
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}
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/**
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* @brief Sets the WWDG Prescaler.
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* @param WWDG_Prescaler: specifies the WWDG Prescaler.
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* This parameter can be one of the following values:
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* @arg WWDG_Prescaler_1: WWDG counter clock = (PCLK1/4096)/1
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* @arg WWDG_Prescaler_2: WWDG counter clock = (PCLK1/4096)/2
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* @arg WWDG_Prescaler_4: WWDG counter clock = (PCLK1/4096)/4
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* @arg WWDG_Prescaler_8: WWDG counter clock = (PCLK1/4096)/8
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* @retval None
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*/
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void WWDG_SetPrescaler(uint32_t WWDG_Prescaler)
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{
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uint32_t tmpreg = 0;
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/* Check the parameters */
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assert_param(IS_WWDG_PRESCALER(WWDG_Prescaler));
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/* Clear WDGTB[1:0] bits */
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tmpreg = WWDG->CFR & CFR_WDGTB_MASK;
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/* Set WDGTB[1:0] bits according to WWDG_Prescaler value */
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tmpreg |= WWDG_Prescaler;
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/* Store the new value */
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WWDG->CFR = tmpreg;
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}
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/**
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* @brief Sets the WWDG window value.
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* @param WindowValue: specifies the window value to be compared to the downcounter.
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* This parameter value must be lower than 0x80.
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* @retval None
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*/
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void WWDG_SetWindowValue(uint8_t WindowValue)
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{
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__IO uint32_t tmpreg = 0;
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/* Check the parameters */
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assert_param(IS_WWDG_WINDOW_VALUE(WindowValue));
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/* Clear W[6:0] bits */
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tmpreg = WWDG->CFR & CFR_W_MASK;
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/* Set W[6:0] bits according to WindowValue value */
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tmpreg |= WindowValue & (uint32_t) BIT_MASK;
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/* Store the new value */
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WWDG->CFR = tmpreg;
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}
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/**
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* @brief Enables the WWDG Early Wakeup interrupt(EWI).
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* @note Once enabled this interrupt cannot be disabled except by a system reset.
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* @param None
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* @retval None
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*/
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void WWDG_EnableIT(void)
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{
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*(__IO uint32_t *) CFR_EWI_BB = (uint32_t)ENABLE;
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}
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/**
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* @brief Sets the WWDG counter value.
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* @param Counter: specifies the watchdog counter value.
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* This parameter must be a number between 0x40 and 0x7F (to prevent generating
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* an immediate reset).
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* @retval None
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*/
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void WWDG_SetCounter(uint8_t Counter)
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{
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/* Check the parameters */
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assert_param(IS_WWDG_COUNTER(Counter));
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/* Write to T[6:0] bits to configure the counter value, no need to do
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a read-modify-write; writing a 0 to WDGA bit does nothing */
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WWDG->CR = Counter & BIT_MASK;
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}
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/**
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* @}
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*/
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/** @defgroup WWDG_Group2 WWDG activation functions
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* @brief WWDG activation functions
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*
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@verbatim
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==============================================================================
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##### WWDG activation function #####
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==============================================================================
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@endverbatim
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* @{
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*/
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/**
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* @brief Enables WWDG and load the counter value.
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* @param Counter: specifies the watchdog counter value.
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* This parameter must be a number between 0x40 and 0x7F (to prevent generating
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* an immediate reset).
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* @retval None
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*/
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void WWDG_Enable(uint8_t Counter)
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{
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/* Check the parameters */
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assert_param(IS_WWDG_COUNTER(Counter));
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WWDG->CR = WWDG_CR_WDGA | Counter;
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}
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/**
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* @}
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*/
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/** @defgroup WWDG_Group3 Interrupts and flags management functions
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* @brief Interrupts and flags management functions
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*
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@verbatim
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==============================================================================
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##### Interrupts and flags management functions #####
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==============================================================================
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@endverbatim
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* @{
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*/
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/**
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* @brief Checks whether the Early Wakeup interrupt flag is set or not.
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* @param None
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* @retval The new state of the Early Wakeup interrupt flag (SET or RESET).
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*/
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FlagStatus WWDG_GetFlagStatus(void)
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{
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FlagStatus bitstatus = RESET;
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if ((WWDG->SR) != (uint32_t)RESET)
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{
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bitstatus = SET;
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}
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else
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{
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bitstatus = RESET;
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}
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return bitstatus;
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}
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/**
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* @brief Clears Early Wakeup interrupt flag.
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* @param None
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* @retval None
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*/
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void WWDG_ClearFlag(void)
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{
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WWDG->SR = (uint32_t)RESET;
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}
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/**
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* @}
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*/
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/**
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* @}
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*/
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/**
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* @}
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*/
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/**
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* @}
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*/
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/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
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