/**
@page WWDG_Example Window Watchdog example
@verbatim
******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
* @file WWDG/WWDG_Example/readme.txt
* @author MCD Application Team
* @brief Description of the Window Watchdog example.
******************************************************************************
*
* Redistribution and use in source and binary forms, with or without modification,
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* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
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* 3. Neither the name of STMicroelectronics nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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*
******************************************************************************
@endverbatim
@par Example Description
This example guides you through the different configuration steps by mean of HAL API
to ensure WWDG counter update at regular period and simulate a software fault
generating an MCU WWDG reset on expiry of a programmed time period.
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 180 MHz.
The WWDG peripheral configuration is ensured by the HAL_WWDG_Init() function.
This later is calling the HAL_WWDG_MspInit()function which core is implementing
the configuration of the needed WWDG resources according to the used hardware (CLOCK,
GPIO, DMA and NVIC). You may update this function to change WWDG configuration.
The WWDG timeout is set, through counter value, to 46 ms.
The refresh window is set in order to make user wait 35 ms after a wadchdog refresh,
before writing again counter. Hence the WWDG counter is refreshed each (35 + 1) ms in the
main program infinite loop to prevent a WWDG reset.
LED2 is also toggled each 40 ms indicating that the program is running.
An EXTI Line is connected to a GPIO pin, and configured to generate an interrupt
on the rising edge of the signal.
The EXTI Line is used to simulate a software failure: once the EXTI Line event
occurs by pressing the Key push-button(PC.13), the corresponding interrupt is served.
In the ISR, a write to invalid address generates a Hardfault exception containing
an infinite loop and preventing to return to main program (the WWDG counter is
not refreshed).
As a result, when the WWDG counter falls to 63, the WWDG reset occurs.
If the WWDG reset is generated, after the system resumes from reset, LED1 turns ON.
If the EXTI Line event does not occur, the WWDG counter is indefinitely refreshed
in the main program infinite loop, and there is no WWDG reset.
LED3 will turn ON, if any error is occurred.
@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 application needs to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@par Keywords
System, WWDG, Downcounter, MCU Reset, Timeout, Software fault
@par Directory contents
- WWDG/WWDG_Example/Inc/stm32f4xx_hal_conf.h HAL configuration file
- WWDG/WWDG_Example/Inc/stm32f4xx_it.h Interrupt handlers header file
- WWDG/WWDG_Example/Inc/main.h Main program header file
- WWDG/WWDG_Example/Src/stm32f4xx_it.c Interrupt handlers
- WWDG/WWDG_Example/Src/main.c Main program
- WWDG/WWDG_Example/Src/stm32f4xx_hal_msp.c HAL MSP module
- WWDG/WWDG_Example/Src/system_stm32f4xx.c STM32F4xx system clock configuration file
@par Hardware and Software environment
- This example runs on STM32F42xxx/STM32F43xxx devices.
- This example has been tested with STM324x9I-EVAL RevB evaluation 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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