Description of hardware watchdog and software watchdog

[kolban]

I understand that a watchdog timer resets the device if control is given to user code and control is not returned within a given time period.

I am starting to read about the concepts of a "hardware" watchdog and a "software" watchdog. These result in the following questions:

- What is the difference between the hardware and software watchdogs?
- What are the timing values for these separate watchdogs?
- What might go wrong if user code were to keep control for too long?
- Is there a way to "yield" control back to the OS from user code but return control and state/context to where I yielded from?
- Do os_delay_us() timers yield control back to the OS?

Many thanks ... Neil