IWDG HAL module driver. This file provides firmware functions to manage the following functionalities of the Independent Watchdog (IWDG) peripheral: More...

#include "stm32h7xx_hal.h"

Detailed Description

IWDG HAL module driver. This file provides firmware functions to manage the following functionalities of the Independent Watchdog (IWDG) peripheral:

Author

MCD Application Team

Initialization and Start functions
IO operation functions

Attention

This software is licensed under terms that can be found in the LICENSE file in the root directory of this software component. If no LICENSE file comes with this software, it is provided AS-IS.

==============================================================================
                  ##### IWDG Generic features #####
==============================================================================
[..]
  (+) The IWDG can be started by either software or hardware (configurable
      through option byte).

  (+) The IWDG is clocked by the Low-Speed Internal clock (LSI) and thus stays
      active even if the main clock fails.

  (+) Once the IWDG is started, the LSI is forced ON and both cannot be
      disabled. The counter starts counting down from the reset value (0xFFF).
      When it reaches the end of count value (0x000) a reset signal is
      generated (IWDG reset).

  (+) Whenever the key value 0x0000 AAAA is written in the IWDG_KR register,
      the IWDG_RLR value is reloaded into the counter and the watchdog reset
      is prevented.

  (+) The IWDG is implemented in the VDD voltage domain that is still functional
      in STOP and STANDBY mode (IWDG reset can wake up the CPU from STANDBY).
      IWDGRST flag in RCC_CSR register can be used to inform when an IWDG
      reset occurs.

  (+) Debug mode: When the microcontroller enters debug mode (core halted),
      the IWDG counter either continues to work normally or stops, depending
      on DBG_IWDG_STOP configuration bit in DBG module, accessible through
      __HAL_DBGMCU_FREEZE_IWDG1() or __HAL_DBGMCU_FREEZE2_IWDG2() and
      __HAL_DBGMCU_UnFreeze_IWDG1 or __HAL_DBGMCU_UnFreeze2_IWDG2() macros.

  [..] Min-max timeout value @32KHz (LSI): ~125us / ~32.7s
       The IWDG timeout may vary due to LSI clock frequency dispersion.
       STM32H7xx devices provide the capability to measure the LSI clock
       frequency (LSI clock is internally connected to TIM16 CH1 input capture).
       The measured value can be used to have an IWDG timeout with an
       acceptable accuracy.

  [..] Default timeout value (necessary for IWDG_SR status register update):
       Constant LSI_VALUE is defined based on the nominal LSI clock frequency.
       This frequency being subject to variations as mentioned above, the
       default timeout value (defined through constant HAL_IWDG_DEFAULT_TIMEOUT
       below) may become too short or too long.
       In such cases, this default timeout value can be tuned by redefining
       the constant LSI_VALUE at user-application level (based, for instance,
       on the measured LSI clock frequency as explained above).

                   ##### How to use this driver #####
==============================================================================
[..]
  (#) Use IWDG using HAL_IWDG_Init() function to :
    (++) Enable instance by writing Start keyword in IWDG_KEY register. LSI
         clock is forced ON and IWDG counter starts counting down.
    (++) Enable write access to configuration registers:
        IWDG_PR, IWDG_RLR and IWDG_WINR.
    (++) Configure the IWDG prescaler and counter reload value. This reload
         value will be loaded in the IWDG counter each time the watchdog is
         reloaded, then the IWDG will start counting down from this value.
    (++) Depending on window parameter:
      (+++) If Window Init parameter is same as Window register value,
           nothing more is done but reload counter value in order to exit
           function with exact time base.
      (+++) Else modify Window register. This will automatically reload
           watchdog counter.
    (++) Wait for status flags to be reset.

  (#) Then the application program must refresh the IWDG counter at regular
      intervals during normal operation to prevent an MCU reset, using
      HAL_IWDG_Refresh() function.

   *** IWDG HAL driver macros list ***
   ====================================
   [..]
     Below the list of most used macros in IWDG HAL driver:
    (+) __HAL_IWDG_START: Enable the IWDG peripheral
    (+) __HAL_IWDG_RELOAD_COUNTER: Reloads IWDG counter with value defined in
        the reload register