STM32F4 Standard Peripheral bibliotheek  1.0
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stm32f4xx_wwdg.c File Reference

This file provides firmware functions to manage the following functionalities of the Window watchdog (WWDG) peripheral: More...

#include "stm32f4xx_wwdg.h"
#include "stm32f4xx_rcc.h"

Macros

#define WWDG_OFFSET   (WWDG_BASE - PERIPH_BASE)
 
#define CFR_OFFSET   (WWDG_OFFSET + 0x04)
 
#define EWI_BitNumber   0x09
 
#define CFR_EWI_BB   (PERIPH_BB_BASE + (CFR_OFFSET * 32) + (EWI_BitNumber * 4))
 
#define CFR_WDGTB_MASK   ((uint32_t)0xFFFFFE7F)
 
#define CFR_W_MASK   ((uint32_t)0xFFFFFF80)
 
#define BIT_MASK   ((uint8_t)0x7F)
 

Functions

void WWDG_DeInit (void)
 Deinitializes the WWDG peripheral registers to their default reset values. More...
 
void WWDG_SetPrescaler (uint32_t WWDG_Prescaler)
 Sets the WWDG Prescaler. More...
 
void WWDG_SetWindowValue (uint8_t WindowValue)
 Sets the WWDG window value. More...
 
void WWDG_EnableIT (void)
 Enables the WWDG Early Wakeup interrupt(EWI). More...
 
void WWDG_SetCounter (uint8_t Counter)
 Sets the WWDG counter value. More...
 
void WWDG_Enable (uint8_t Counter)
 Enables WWDG and load the counter value. More...
 
FlagStatus WWDG_GetFlagStatus (void)
 Checks whether the Early Wakeup interrupt flag is set or not. More...
 
void WWDG_ClearFlag (void)
 Clears Early Wakeup interrupt flag. More...
 

Detailed Description

This file provides firmware functions to manage the following functionalities of the Window watchdog (WWDG) peripheral:

Author
MCD Application Team
Version
V1.0.2
Date
05-March-2012
  • Prescaler, Refresh window and Counter configuration
  • WWDG activation
  • Interrupts and flags management
*    
*          ===================================================================
*                                     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 @42 MHz(PCLK1): ~97.5 us / ~49.9 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().         
*
*  
Attention

© COPYRIGHT 2012 STMicroelectronics

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