How this works
Timeout = (prescaler × reload) / Fclk, matching the common independent-watchdog model (e.g. STM32 IWDG) where the effective tick rate is Fclk/prescaler and the counter counts down from the reload value. Exact formulas vary by peripheral (some watchdogs use a fixed reference clock, others count up), so confirm against your MCU's reference manual before relying on this for a safety-critical timeout.