stm32f30x_iwdg.c File Reference

This file provides firmware functions to manage the following functionalities of the Independent watchdog (IWDG) peripheral: + Prescaler and Counter configuration + IWDG activation + Flag management. More...

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Detailed Description

This file provides firmware functions to manage the following functionalities of the Independent watchdog (IWDG) peripheral: + Prescaler and Counter configuration + IWDG activation + Flag management.

Author:

MCD Application Team

Version:

V1.2.3

Date:

10-July-2015

  
 ===============================================================================
                          ##### IWDG features #####
 ===============================================================================
    [..] The IWDG can be started by either software or hardware (configurable
         through option byte).
    [..] The IWDG is clocked by its own dedicated low-speed clock (LSI) and
         thus stays active even if the main clock fails.
         Once the IWDG is started, the LSI is forced ON and cannot be disabled
         (LSI cannot be disabled too), and the counter starts counting down from 
         the reset value of 0xFFF. When it reaches the end of count value (0x000)
         a system reset is generated.
         The IWDG counter should be reloaded at regular intervals to prevent
         an MCU reset.
    [..] The IWDG is implemented in the VDD voltage domain that is still functional
         in STOP and STANDBY mode (IWDG reset can wake-up from STANDBY).          
    [..] IWDGRST flag in RCC_CSR register can be used to inform when a IWDG
         reset occurs.
    [..] Min-max timeout value @41KHz (LSI): ~0.1ms / ~25.5s
         The IWDG timeout may vary due to LSI frequency dispersion. STM32F30x
         devices provide the capability to measure the LSI frequency (LSI clock
         connected internally to TIM16 CH1 input capture). The measured value
         can be used to have an IWDG timeout with an acceptable accuracy. 
         For more information, please refer to the STM32F30x Reference manual.

                      ##### How to use this driver #####
 ===============================================================================
    [..] This driver allows to use IWDG peripheral with either window option enabled
         or disabled. To do so follow one of the two procedures below.
    (#) Window option is enabled:    
        (++) Start the IWDG using IWDG_Enable() function, when the IWDG is used
             in software mode (no need to enable the LSI, it will be enabled
             by hardware).        
        (++) Enable write access to IWDG_PR and IWDG_RLR registers using
             IWDG_WriteAccessCmd(IWDG_WriteAccess_Enable) function.
        (++) Configure the IWDG prescaler using IWDG_SetPrescaler() function.
        (++) Configure the IWDG counter value using IWDG_SetReload() function.
             This value will be loaded in the IWDG counter each time the counter
             is reloaded, then the IWDG will start counting down from this value.
        (++) Wait for the IWDG registers to be updated using IWDG_GetFlagStatus() function.
        (++) Configure the IWDG refresh window using IWDG_SetWindowValue() function.

    (#) Window option is disabled:    
        (++) Enable write access to IWDG_PR and IWDG_RLR registers using
             IWDG_WriteAccessCmd(IWDG_WriteAccess_Enable) function.
        (++) Configure the IWDG prescaler using IWDG_SetPrescaler() function.
        (++) Configure the IWDG counter value using IWDG_SetReload() function.
             This value will be loaded in the IWDG counter each time the counter
             is reloaded, then the IWDG will start counting down from this value.
        (++) Wait for the IWDG registers to be updated using IWDG_GetFlagStatus() function.
        (++) reload the IWDG counter at regular intervals during normal operation 
             to prevent an MCU reset, using IWDG_ReloadCounter() function.
        (++) Start the IWDG using IWDG_Enable() function, when the IWDG is used
             in software mode (no need to enable the LSI, it will be enabled
             by hardware).    
          
  

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Definition in file stm32f30x_iwdg.c.