IWDG HAL module driver. This file provides firmware functions to manage the following functionalities of the Independent Watchdog (IWDG) peripheral: + Initialization and Start functions + IO operation functions.
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IWDG HAL module driver. This file provides firmware functions to manage the following functionalities of the Independent Watchdog (IWDG) peripheral: + Initialization and Start functions + IO operation functions.
- Author:
- MCD Application Team
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##### IWDG Generic features #####
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[..]
(+) The IWDG can be started by either software or hardware (configurable
through option byte).
(+) The IWDG is clocked by 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 both can not 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 in 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 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_IWDG() and __HAL_DBGMCU_UNFREEZE_IWDG() macros
[..] Min-max timeout value @32KHz (LSI): ~125us / ~32.7s
The IWDG timeout may vary due to LSI frequency dispersion. STM32F4xx
devices provide the capability to measure the LSI frequency (LSI clock
connected internally to TIM5 CH4 input capture). The measured value
can be used to have an IWDG timeout with an acceptable accuracy.
##### How to use this driver #####
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[..]
(#) 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 downcounting.
(++) Enable write access to configuration register: IWDG_PR & IWDG_RLR.
(++) 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.
(++) 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 ***
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[..]
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
- Attention:
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Definition in file stm32f4xx_hal_iwdg.c.
