Well, NRST can also output an internally generated reset as a ≥20µs pulse to the outside electronics, but it is still not comparable with a GPIO, which is why no maximum current is specified for it. Typically, you would connect external digital inputs to NRST, for which the current requirement is usually negligible.
However, you can still drive an optocoupler as you have drawn if its LED current is not too large. Since NRST is driven internally by a CMOS transistor, the resulting voltage at NRST depends on the flowing current. This voltage must remain clearly below VIL of internal and external logic so that both can detect the reset. With low current optocouplers, however, this should be easily achievable.
Does it answer your question?
If the problem is solved, please mark this thread as answered by selecting Select as best, as also explained here. This will help other users find that answer faster.
Good luck!
Regards
/Peter
In order to give better visibility on the answered topics, please click on Accept as Solution on the reply which solved your issue or answered your question.
