Why don't my PORTB pulse? (The level is constant in all BITS of PORTB...
  )

Can you see what i'm doing wrong?
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(code snipped, I hate crossposting)

The code looks good to me. Your PORTB levels are constant looking with an
oscilloscope? or too fast to detect with your detection device? Maybe is a
bit silly anwer but if you are using a multimeter or something like this,
you never will detect changes, if your clock is in the MHz range..

Hope it helps

Sebastian Dols