watchdog – Watchdog Timer¶
The watchdog module provides support for a Watchdog Timer. This timer will reset the device
if it hasn’t been fed after a specified amount of time. This is useful to ensure the board
has not crashed or locked up. Note that on some platforms the watchdog timer cannot be disabled
once it has been enabled.
The WatchDogTimer is used to restart the system when the application crashes and ends
up into a non recoverable state. Once started it cannot be stopped or
reconfigured in any way. After enabling, the application must “feed” the
watchdog periodically to prevent it from expiring and resetting the system.
Example usage:
from microcontroller import watchdog as w
from watchdog import WatchDogMode
w.timeout=2.5 # Set a timeout of 2.5 seconds
w.mode = WatchDogMode.RAISE
w.feed()
Available on these boards
- exception watchdog.WatchDogTimeout¶
Bases:
ExceptionException raised when the watchdog timer is set to
WatchDogMode.RAISEand expires.Example:
import microcontroller import watchdog import time wdt = microcontroller.watchdog wdt.timeout = 5 while True: wdt.mode = watchdog.WatchDogMode.RAISE print("Starting loop -- should exit after five seconds") try: while True: time.sleep(10) # Also works with pass except watchdog.WatchDogTimeout as e: print("Watchdog expired") except Exception as e: print("Other exception") print("Exited loop")
Initialize self. See help(type(self)) for accurate signature.
- class watchdog.WatchDogMode¶
run state of the watchdog timer
Enum-like class to define the run mode of the watchdog timer.
- RAISE :WatchDogMode¶
Raise an exception when the WatchDogTimer expires.
- RESET :WatchDogMode¶
Reset the system if the WatchDogTimer expires.
- class watchdog.WatchDogTimer¶
Timer that is used to detect code lock ups and automatically reset the microcontroller when one is detected.
A lock up is detected when the watchdog hasn’t been fed after a given duration. So, make sure to call
feedwithin the timeout.Not currently dynamically supported. Access the sole instance through
microcontroller.watchdog.- timeout :float¶
The maximum number of seconds that can elapse between calls to feed()
- mode :WatchDogMode¶
The current operating mode of the WatchDogTimer
watchdog.WatchDogMode.Setting a WatchDogMode activates the WatchDog:
import microcontroller import watchdog w = microcontroller.watchdog w.timeout = 5 w.mode = watchdog.WatchDogMode.RAISE
Once set, the WatchDogTimer will perform the specified action if the timer expires.