115 lines
4.8 KiB
Plaintext
115 lines
4.8 KiB
Plaintext
/**
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@page IWDG_Reset Independent Watchdog Reset Example
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@verbatim
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********************* COPYRIGHT(c) 2016 STMicroelectronics *******************
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* @file IWDG/IWDG_Reset/readme.txt
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* @author MCD Application Team
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* @brief Description of the IWDG Reset.
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******************************************************************************
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* @attention
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*
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* Copyright (c) 2016 STMicroelectronics.
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* All rights reserved.
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*
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* This software is licensed under terms that can be found in the LICENSE file
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* in the root directory of this software component.
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* If no LICENSE file comes with this software, it is provided AS-IS.
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*
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******************************************************************************
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@endverbatim
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@par Example Description
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How to handle the IWDG reload counter and simulate a software fault that generates
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an MCU IWDG reset after a preset laps of time.
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At the beginning of the main program the HAL_Init() function is called to reset
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all the peripherals, initialize the Flash interface and the systick.
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Then the SystemClock_Config() function is used to configure the system
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clock (SYSCLK) to run at 48 MHz.
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The IWDG timeout is set to 1 second.
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First, the TIM14 timer is configured to measure the LSI frequency as the
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LSI is internally connected to TIM14 CH1, in order to adjust the IWDG clock.
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The LSI frequency value could be monitored on debugger in "uwLsiFreq" variable.
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The LSI measurement using the TIM14 is described below:
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- Configure the TIM14 to remap internally the TIM14 CH1 Input Capture to the LSI
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clock output.
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- Enable the TIM14 Input Capture interrupt: after one cycle of LSI clock, the
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period value is stored in a variable and compared to the HCLK clock to get
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its real value.
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Then, the IWDG reload counter is configured as below to obtain 1 second according
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to the measured LSI frequency after setting the prescaler value:
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IWDG counter clock Frequency = LSI Frequency / Prescaler value
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The IWDG reload counter is refreshed each 990 ms in the main program infinite
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loop to prevent a IWDG reset.
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LED2 is also toggling each 990 ms indicating that the program is running.
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An EXTI Line is connected to a GPIO pin, configured to generate an interrupt
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when the User push-button (PC.13) is pressed.
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The EXTI Line is used to simulate a software failure: once the EXTI Line event
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occurs by pressing the User push-button (PC.13), the corresponding interrupt is served.
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In the ISR, a write to invalid address generates a Hardfault exception
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containing an infinite loop and preventing to return to main program (the IWDG
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reload counter is not refreshed).
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As a result, when the IWDG counter reaches 0, the IWDG reset occurs.
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If the IWDG reset is generated, after the system resumes from reset, LED2 turns on for 4 seconds.
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If the EXTI Line event does not occur, the IWDG counter is indefinitely refreshed in the main
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program infinite loop, and there is no IWDG reset.
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If the user button is pressed while LED2 is turned on, another Hardfault exception is triggered.
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In this case, since the IWDG has not been reprogrammed yet, the software ends up
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stuck in the hardfault. All LEDs are turned off in this situation.
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LED2 will turn off if any error occurs.
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@note Care must be taken when using HAL_Delay(), this function provides accurate
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delay (in milliseconds) based on variable incremented in SysTick ISR. This
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implies that if HAL_Delay() is called from a peripheral ISR process, then
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the SysTick interrupt must have higher priority (numerically lower)
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than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
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To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
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@note The application need to ensure that the SysTick time base is always set to 1 millisecond
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to have correct HAL operation.
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@par Directory contents
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- IWDG/IWDG_Reset/Inc/stm32f0xx_hal_conf.h HAL configuration file
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- IWDG/IWDG_Reset/Inc/stm32f0xx_it.h Interrupt handlers header file
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- IWDG/IWDG_Reset/Inc/main.h Header for main.c module
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- IWDG/IWDG_Reset/Src/stm32f0xx_it.c Interrupt handlers
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- IWDG/IWDG_Reset/Src/main.c Main program
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- IWDG/IWDG_Reset/Src/stm32f0xx_hal_msp.c HAL MSP file
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- IWDG/IWDG_Reset/Src/system_stm32f0xx.c STM32F0xx system source file
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@par Hardware and Software environment
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- This example runs on STM32F0xx devices.
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- This example has been tested with STM32F072RB-Nucleo RevC board and can be
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easily tailored to any other supported device and development board.
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@par How to use it ?
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In order to make the program work, you must do the following :
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- Open your preferred toolchain
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- Rebuild all files and load your image into target memory
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- Run the example
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*/
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