Any Faster RMS Value Calculation in C?

Question

I am writing a software for a small 8-bit microcontroller in C. Part of the code is to read the ADC value of a current transformer (ZCT), and then calculate the RMS value. T

Answer 1

Hopefully your project is for measuring "Big" AC voltages ( and not something like 9v motor control. ) If this happens to be the case then you can cheat because your error can then be within accepted limits..

Do all of the maths in integer, and use a simple lookup map for the sqrt operation. ( which you can pre-calculate at startup, you would only REALLY need about ~600 odd values if you are doing 3 phase..

Also this begs the question do you ACTUALLY need VAC RMS or some other measure of power ? (for example can you get away with a simple box mean algorythm? )