The minimum is 1 millisecond, but you should never set it that short since it will frequently fire as the thread scheduler works at 1 millisecond timeslices, and any delays caused by high priority threads or disabled interrupts will exceed that limit.
The maximium varies by platform:
- Boron, B Series SoM, Argon, Tracker SoM (nRF52840): 131,071,999 milliseconds
- P2 and Photon 2 (RTL872x): 8,190,000 milliseconds (around 2 hours and 15 minutes)
On nRF52840 (Boron, B Series SoM, Argon, Tracker SoM) devices, you can optionally keep the watchdog running during sleep by using a capabilities flag:
Watchdog.init(WatchdogConfiguration() .capabilities(WatchdogCap::SLEEP_RUNNING) .timeout(20min)); Watchdog.start();