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.
UINT32_MAXmilliseconds is the maximum allowed max_timeout
hal_watchdog_get_platform_features()returns; minimum timeout is 1 ms.
- The uncalibrated watchdog should trigger at or after the timeout value multiplied by the frequency accuracy ratio of its oscillator (typical_frequency divided by max_frequency).
- The calibrated watchdog should trigger at or after the timeout value.
- The watchdog should trigger before twice the timeout value.
- The watchdog may trigger as late as twice the timeout value in deep sleep mode.
- 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.
Hardware Independent Watchdog support.
You can find the API and specification for the Watchdog API in its HAL API reference:
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*"
For more details, please see: