Hi Jacek,

again, your code was not fully wrong. I miss only the right detection of the start and the stop point.
Thus, why you get wrong results.

Please make a plan like this:

- first 1-0 transition: start T0
- first 0-1 transition: stop T0, start T1
- second 1-0 transition: stop T1
- read T0
- read T1

You can see, that your routine not meet this scheme, since:

A transition triggerd interrupt was not served immediately after the transition, if disabled. So enabling 1 year later causes, that it was also served 1 year later.
Thus a typical enabling sequence was:

clr IE0 ;reset, if it was already set on earlier trigger events
setb EX0 ;enable to detect the next trigger event

Also all other interrupts should be enabled in this way. Since in most cases it was not desired to serve events, which happens long time ago.



Peter