Watchdog module¶
The watchdog module is responsible for controlling the watchdog timer.
The watchdog timer is used to prevent hangs caused by software or hardware faults. When the system hangs, it is automatically restarted by the watchdog timer.
Module events¶
Source Module |
Input Event |
This Module |
Output Event |
Sink Module |
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Note
See the Overview: Firmware architecture for more information about the event-based communication in the nRF Desktop application and about how to read this table.
Configuration¶
The module uses Zephyr’s Watchdog driver.
For this reason, set the CONFIG_WATCHDOG option.
The module is enabled by the CONFIG_DESKTOP_WATCHDOG_ENABLE option.
You must define CONFIG_DESKTOP_WATCHDOG_TIMEOUT.
After this amount of time (in ms), the device will be restarted if the watchdog timer was not reset.
Note
The module is used only in the release configurations (ZRelease, ZReleaseB0).
For the debug configurations (ZDebug, ZDebugWithShell, ZDebugB0), enabling watchdog timer can cause losing logs, for example when the logger is in the panic mode.
Implementation details¶
The watchdog timer is started when the Basic module (main) is ready (which is reported using module_state_event).
The module periodically resets the watchdog timer using k_work_delayable.
The work resubmits itself with delay equal to CONFIG_DESKTOP_WATCHDOG_TIMEOUT / 3.
In case of the system hang, the work will not be processed, the watchdog timer will not be reset on time, and the system will be restarted.