interrupt (event)

[trix]

hello,

I have a stepper motor that I steer from left to the right.
1 cm = 100 pulses.
Now I want to send data with the UART to a scanner, every time 1cm is passed (100 pulses).
To prevent sending that data from affecting the stepper movement, I want to do that in an interrupt routine.
so i think i need een "event interrupt".
but i don't no how this works,...maybe someone can help me with this.
thank you.