internal watchdog

There is no need for an external watchdog as there are two watchdogs already built in:

• IWDG - Independent Watchdog, comparable to an external one due to the independent clock
• WWDG - Windowed Watchdog, flexible due to with two time limits, but supplied with normal clock source

You will find more information in RM0433.

Regards

Peter

Most stm32 ('h743 included) have two internal watchdogs that can be used to reset the uC.

There is the Window Watchdog WWDG that runs from the APB bus clock. This watchdog is fairly sophisticated and has means for detecting "spurious" refreshes (in case the program might have crashed in a way that is accidentally refreshing the watchdog) and resetting under those circumstances as well.

This has the disadvantage that if the APB clock is stopped, so is the watchdog.

And the Independent Watchdog. This is relatively simple, but has its own hardware oscillator so once it is started, it can't be turned off without a reset.

External HW watchdog?

I tend to put MAX823 as a power-on-reset with built-in watchdog (from the days when power-on-reset built into microcontrollers wasn't very reliable). I haven't had cause to stop putting it in (which might be down to cost or board area) so I still put it in.

Hope this helps,

Danish