will an interrupt mess up my arduino serial out

Hi, I'm in the process of using 3 or 4 74hc595 shift registers to control a pov display I'm trying to make. I use a hall effect sensor (finally working!) to keep track of rotations.

I haven't hooked both systems up together yet (leds AND hall effect), so I'm not sure how this is going to work. if I use attachInterrupt on the hall effect sensor to call a function that adjusts for any small change in motor speed (it seems to vary between 900-1000rpm), will that completely destroy the data going out to the shift registers at that point? because, well, its interrupted... :)

also, I have 27 leds. If I use 3 shift registers for the first 24, will hooking the last 3 directly up to the arduino alter their timing any? I don't know if there's a noticeable delay between turning on an arduino pin, or sending data out through 3 daisy-chained shift registers

if there's a noticeable delay between turning on an arduino pin, or sending data out through 3 daisy-chained shift registers

The data doesn't get transferd to the output of a shift register until you change the load pin, then all the shift registers outputs change at once. If you follow this by three digitalWrites the delay will be less than a millisecond.

will that completely destroy the data going out to the shift registers at that point? because, well, its interrupted

Any time in an interrupt service routine will be subtracted from the main running code. However it won't destroy the data, at worst it will give a small visible glitch.