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stm32f4xx_wwdg.c
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/**
******************************************************************************
* @file stm32f4xx_wwdg.c
* @author MCD Application Team
* @version V1.0.0RC1
* @date 25-August-2011
* @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 @30 MHz(PCLK1): ~136.5 us / ~69.9 ms
*
* ===================================================================
* How to use this driver
* ===================================================================
* 1. Enable WWDG clock using RCC_APB1PeriphClockCmd(RCC_APB1Periph_WWDG, ENABLE) function
*
* 2. Configure the WWDG prescaler using WWDG_SetPrescaler() function
*
* 3. Configure the WWDG refresh window using WWDG_SetWindowValue() function
*
* 4. 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.
*
* 5. 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.
*
* 6. 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
*
* 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.
*
* <h2><center>&copy; COPYRIGHT 2011 STMicroelectronics</center></h2>
******************************************************************************
*/
/* Includes ------------------------------------------------------------------*/
#include "stm32f4xx_wwdg.h"
#include "stm32f4xx_rcc.h"
/** @addtogroup STM32F4xx_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 2011 STMicroelectronics *****END OF FILE****/