Did you ever come across a µController on which every part of
your program works fine, except the Timer2-ISR?

I wanted to measure distance with a US-sensor and show the
result on a LCD. Everything worked fine when I triggered the
US-sensor by a simple press of a button. Next, I tried to
use Timer 2 interrupt for continuos triggering every 50 to
60 ms. At first I thought of a mistake in initializing Timer 2:
Some mysterious bit would not be set properly. I wrote little
test routines, but to no avail.

Tomorrow morning I took another 89S52 from an existing project:
And Timer 2 gives an interrupt! Then I tested every feature on
the first chip - ISP, ports, timers, external interupts, all
of them is o.k., except Timer 2.

Maybe Atmel has sold me a '51 chip in a '52 case ? ;-)
But I suppose there is no such thing as a 89S51.

Thank You Erik for Your interest in my problem.

Greetings from old Germany

Jack Braun