I am designing a power-constrained device that has to gather some data, run from a battery for a couple of years and send data periodically. I want to ensure high reliability, because the device will not be easily accessible.
The MCU is an EFM32. Most of the time all sensing is handled by hardware peripherals. RAM is retained. RTC is running and periodically waking the CPU (let's say once every 24h).
I can turn the watchdog on when the CPU is woken up. Maximum watchdog period is around 250 seconds, which is much shorter than my sleep time. I know that it may save the day if the application hangs while CPU is active, but are there any design patterns that improve reliability when the CPU is sleeping? I don't have power budget for another chip or a second MCU.