Hi Steve and Jay,

but only in the transition triggered mode !!!

In the level triggered mode, the interrupt flag looks like read only and represent always the inverted state of the interrupt pin.
So it can only be set by driving the pin low (external or internal) and was cleared automatically, if the pin goes high.

The level triggered mode is useful with external peripherals, e.g. a CAN controller (SJA1000).
So, if during handling an interrupt a second interrupt event occur, the pin remains still low and after RETI the interrupt was entered again to handle this second event.
But on transition triggered interrupts, the second event was lost !


Peter