The Watchdog HAL API provides a low-level interface to the Independent Watchdog Timer of a target. Implementing the Watchdog API is not mandatory, but by implementing it, you can use the hardware watchdog timer to detect and recover from computer malfunctions.
Implement the ResetReason API when implementing the Watchdog API. The ResetReason API allows you to detect at boot time whether a watchdog caused the last reset.
- Sleep and debug modes don't stop the watchdog timer from counting down.
- The function
hal_watchdog_initis safe to call repeatedly. The function's implementation must not do anything if
hal_watchdog_inithas already initialized the hardware watchdog timer.
- Maximum supported timeout is
UINT32_MAXmilliseconds; minimum timeout is 1ms.
- The timeout must be accurate to the nearest millisecond.
- Calling any function other than
hal_watchdog_get_platform_featuresbefore you have initialized the watchdog.
- A software reset may not stop the watchdog timer; the behavior is platform specific.
- Timing on most platforms is based on the timeout registers and a prescaler value. They should be accurate to the nearest millisecond but may be off my a several µs.
Hardware Independent Watchdog support.
You can find the API and specification for the Watchdog API in the following header file:
|Public Member Functions|
|watchdog_status_t||start (const uint32_t timeout)|
|Start an independent watchdog timer with specified parameters. More...|
|Refreshes the watchdog timer. More...|
|Stops the watchdog timer. More...|
|uint32_t||reload_value () const|
|Get the watchdog timer refresh value. More...|
|Static Public Member Functions|
|static uint32_t||max_timeout ()|
|Get the maximum refresh value for the current platform in milliseconds. More...|
To enable Watchdog support in Mbed OS, add the
WATCHDOG label in the
device_has option of the target's section in the
The Mbed OS HAL provides a set of conformance tests for Watchdog. You can use these tests to validate the correctness of your implementation. To run the Watchdog HAL tests use the following command:
mbed test -t <toolchain> -m <target> -n "tests-mbed_hal-watchdog*"
You can read more about the test cases here: