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

#include "stm32f7xx_hal.h"

Detailed Description

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

Author: MCD Application Team

Version: V1.1.0

Date

22-April-2016

Initialization and Configuration function

IO operation functions

==============================================================================
                    ##### WWDG specific features #####
==============================================================================
[..]
  Once enabled the WWDG generates a system reset on expiry of a programmed
  time period, unless the program refreshes the counter (T[6;0] downcounter)
  before reaching 0x3F value (i.e. a reset is generated when the counter
  value rolls over from 0x40 to 0x3F).

  (+) An MCU reset is also generated if the counter value is refreshed
      before the counter has reached the refresh window value. This
      implies that the counter must be refreshed in a limited window.

  (+) Once enabled the WWDG cannot be disabled except by a system reset.

  (+) WWDGRST flag in RCC_CSR register informs when a WWDG reset has 
      occurred (check available with __HAL_RCC_GET_FLAG(RCC_FLAG_WWDGRST)).

  (+) The WWDG downcounter input clock is derived from the APB clock divided
      by a programmable prescaler.

  (+) WWDG downcounter clock (Hz) = PCLK1 / (4096 * Prescaler)

  (+) WWDG timeout (ms) = (1000 * (T[5;0] + 1)) / (WWDG downcounter clock)
      where T[5;0] are the lowest 6 bits of downcounter.

  (+) WWDG Counter refresh is allowed between the following limits :
      (++) min time (ms) = (1000 * (T[5;0] - Window)) / (WWDG downcounter clock)
      (++) max time (ms) = (1000 * (T[5;0] - 0x40)) / (WWDG downcounter clock)

  (+) Min-max timeout value @80 MHz(PCLK1): ~51.2 us / ~26.22 ms

  (+) The Early Wakeup Interrupt (EWI) can be used if specific safety 
      operations or data logging must be performed before the actual reset is
      generated. When the downcounter reaches the value 0x40, an EWI interrupt
      is generated and the corresponding interrupt service routine (ISR) can 
      be used to trigger specific actions (such as communications or data 
      logging), before resetting the device.
      In some applications, the EWI interrupt can be used to manage a software
      system check and/or system recovery/graceful degradation, without 
      generating a WWDG reset. In this case, the corresponding interrupt 
      service routine (ISR) should reload the WWDG counter to avoid the WWDG 
      reset, then trigger the required actions.
      Note:When the EWI interrupt cannot be served, e.g. due to a system lock 
      in a higher priority task, the WWDG reset will eventually be generated.

  (+) Debug mode : When the microcontroller enters debug mode (core halted),
      the WWDG counter either continues to work normally or stops, depending 
      on DBG_WWDG_STOP configuration bit in DBG module, accessible through
      __HAL_DBGMCU_FREEZE_WWDG() and __HAL_DBGMCU_UNFREEZE_WWDG() macros

                   ##### How to use this driver #####
==============================================================================
[..]
  (+) Enable WWDG APB1 clock using __HAL_RCC_WWDG_CLK_ENABLE().

  (+) Set the WWDG prescaler, refresh window, counter value and Early Wakeup 
      Interrupt mode using using HAL_WWDG_Init() function.
      This enables WWDG peripheral and the downcounter starts downcounting 
      from given counter value.
      Init function can be called again to modify all watchdog parameters, 
      however if EWI mode has been set once, it can't be clear until next 
      reset.

  (+) The application program must refresh the WWDG counter at regular
      intervals during normal operation to prevent an MCU reset using
      HAL_WWDG_Refresh() function. This operation must occur only when
      the counter is lower than the window value already programmed.

  (+) if Early Wakeup Interrupt mode is enable an interrupt is generated when 
      the counter reaches 0x40. User can add his own code in weak function 
      HAL_WWDG_EarlyWakeupCallback().

   *** WWDG HAL driver macros list ***
   ==================================
   [..]
     Below the list of most used macros in WWDG HAL driver.

    (+) __HAL_WWDG_GET_IT_SOURCE: Check the selected WWDG's interrupt source.
    (+) __HAL_WWDG_GET_FLAG: Get the selected WWDG's flag status.
    (+) __HAL_WWDG_CLEAR_FLAG: Clear the WWDG's pending flags.

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Definition in file stm32f7xx_hal_wwdg.c.

Detailed Description

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