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.
- RAISE: WatchDogMode
Raise an exception when the
WatchDogTimerexpires.
- RESET: WatchDogMode
Reset the system when the
WatchDogTimerexpires.
- 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.Access the sole instance through
microcontroller.watchdog.- feed() None
Feed the watchdog timer. This must be called regularly, otherwise the timer will expire. Silently does nothing if the watchdog isn’t active.
- deinit() None
Stop the watchdog timer.
- Raises:
RuntimeError – if the watchdog timer cannot be disabled on this platform.
- timeout: float
The maximum number of seconds that can elapse between calls to
feed(). Setting the timeout will also feed the watchdog.
- mode: WatchDogMode | None
The current operating mode of the WatchDogTimer
watchdog.WatchDogModeorNonewhen the timer is disabled.Setting a
WatchDogModeactivates the WatchDog:from microcontroller import watchdog from watchdog import WatchDogMode watchdog.timeout = 5 watchdog.mode = WatchDogMode.RESET
Once set, the
WatchDogTimerwill perform the specified action if the timer expires.