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/**
@page IWDG_WindowMode IWDG Reset with window mode
@verbatim
********************* COPYRIGHT(c) 2019 STMicroelectronics *******************
* @file IWDG/IWDG_WindowMode/readme.txt
* @author MCD Application Team
* @brief Description of the IWDG Reset with window mode.
******************************************************************************
*
* Copyright (c) 2019-2021 STMicroelectronics.
* All rights reserved.
*
* 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.
*
******************************************************************************
@endverbatim
@par Example Description
How to periodically update the IWDG reload counter and simulate a software fault that generates
an MCU IWDG reset after a preset laps of time.
At the beginning of the main program the HAL_Init() function is called to reset
all the peripherals, initialize the Flash interface and the systick.
Then the SystemClock_Config() function is used to configure the system
clock (SYSCLK) to run at 64 MHz.
The IWDG time-out is set to 762 ms (the time-out may varies due to LSI frequency
dispersion).
The Window option is enabled with a window register value set to 400 ms.
To prevent a reset, the down-counter must be reloaded when its value is:
-lower than the window register value (400ms)
-greater than 0x0
The IWDG counter is therefore refreshed each 450 ms in the main program infinite loop to
prevent a IWDG reset (762 - 450 = 312 within the interval).
LED2 is also toggled each 450 ms indicating that the program is running.
LED3 will turn on if any error occurs.
An EXTI Line is connected to a GPIO pin, configured to generate an interrupt
when the User push-button (SW1) (PA.00) is pressed.
Once the EXTI Line event occurs by pressing the User push-button (SW1) (PA.00),
the refresh period is set to 200 ms.
That will make refresh being outside window value. As a result, when the IWDG counter is reloaded,
the IWDG reset occurs.
In the ISR, a write to invalid address generates a Hard fault exception containing
an infinite loop and preventing to return to main program (the IWDG counter is
not refreshed).
As a result, when the IWDG counter falls to 0, the IWDG reset occurs.
If the IWDG reset is generated, after the system resumes from reset, LED2 turns on for 4 seconds.
If the EXTI Line event does not occur, the IWDG counter is indefinitely refreshed
in the main program infinite loop, and there is no IWDG reset.
@note Care must be taken when using HAL_Delay(), this function provides accurate
delay (in milliseconds) based on variable incremented in SysTick ISR. This
implies that if HAL_Delay() is called from a peripheral ISR process, then
the SysTick interrupt must have higher priority (numerically lower)
than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
@note The example needs to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@par Keywords
System, IWDG, reload counter, MCU Reset, Window mode, Timeout, Software fault
@par Directory contents
- IWDG/IWDG_WindowMode/Inc/nucleo_wb15cc_conf.h BSP configuration file
- IWDG/IWDG_WindowMode/Inc/stm32wbxx_hal_conf.h HAL configuration file
- IWDG/IWDG_WindowMode/Inc/stm32wbxx_it.h Interrupt handlers header file
- IWDG/IWDG_WindowMode/Inc/main.h Header for main.c module
- IWDG/IWDG_WindowMode/Src/stm32wbxx_it.c Interrupt handlers
- IWDG/IWDG_WindowMode/Src/main.c Main program
- IWDG/IWDG_WindowMode/Src/system_stm32wbxx.c STM32WBxx system source file
@par Hardware and Software environment
- This example runs on STM32WB15CCUx devices.
- This example has been tested with NUCLEO-WB15CC board and can be
easily tailored to any other supported device and development board.
@par How to use it ?
In order to make the program work, you must do the following :
- Open your preferred toolchain
- Rebuild all files and load your image into target memory
- Run the example
* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
*/
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