bikash,

With the '51 stack arrangement, an interrupt processes should always careful in regard to stack utilization.

An interrupt can occur withing a deeply nested foreground outine.


If you use multiple priority interrupts then an interrupt can occur within another interrupt within a deeply nested foreground routine.

This is why most folks minimize stack utilization during interrupt. This is also why folks try not to nest to deeply on the '51 in general.

There are many simple ways to watch or profile your stack and if you use them to ensure stack "freeboard", subroutines are ok.

Be careful, unintentional resource contention between foreground and interrupts can result from the use of subroutines characterized for foreground use.

Erik's comment about short routines that set flags to signal additional foreground execution is a very safe technique which keeps interrupts from getting "out of hand" either in time or "path-length".


regards,
p