Hi Al,

please look at my example:

http://www.specs.de/~danni/training/reti.a51
http://www.specs.de/~danni/training/reti.hex

If, as you assumed, the count of RETI was unimportant, it must end with the value 6 on port P1.
But in reality it stops already with the value 5.

I hope this improve you 8051 skills about interrupts.


Hi Stefleus,

this example works exactly, as you asked for, but it is not easy to understand for beginners.
You should simulate it step by step and review all sections in the data sheet about the interrupt logic.


Peter