Hi all,

Can anyone tell me how to work out how long an instruction takes to execute when running at 20MHz?

I have some software for firing a 3 phase bridge rectifier using thyristors. It now needs modifying to work on 50 or 60Hz. working with 50Hz just required a simple pauseus. Now it needs an if then else.

if frequency = 50 then
pauseus 1533 'delay for 60 degrees on 50Hz
else
pauseus 977 'delay for 60Hz
endif

The way phase angle firing works means that you get 6 peaks of current every mains cycle but the peaks are uneven, by as much as 200A.
I think this is because of the extra time the if then takes to run.

This just got me thinking how can I work out the time it takes to run an instruction, for time sensitive applications.

Regards
Bob...