Quote Originally Posted by skimask View Post
What does this do on PortD.0?

My point is that it looks like your program 'flow' is jacked up and needs to be reworked.
I've done that. It shows 4330Hz...

Quote Originally Posted by Darrel Taylor View Post
Sylvio,

This may sound silly, but are you sure it's a 20mhz crystal?

A 4mhz crystal with that Timer1 reload value would give ~870 hz.
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Yes, I am sure about it.. It is a 20Mhz Xtal.. Then ~900Hz is the frequency that the block (if flag = 1 ..) is running, but no the timer1 interrupt...

Thanks !