Thank you Allan,

it seems, you are the first, which read my example.


The external interrupt problem must be watched on any using, not only on my example:

- on level sensitive any interrupt must be hold active until the interrupt service routine was entered

- on transition sensitive the interrupt flag was set on any low transition and this cause that the interrupt was serviced, whenever possible.
Since it was cleared on entering the interrupt routine, the next transition can be detected immediately after this and the interrupt routine must not be already finished.


Peter