Zero cross detect - switching audio

[cncmachineguy]

Then I will have to agree with you. Now you could do it in reverse, on EVERY ZC, call ISR, Check for switch pressed or released, if it is, turn on thingy, of not leave.
Or use the ZC as the timing for main.

while not ZC :WEND
switch pressed do stuff
released do other stuff
continue to twiddle bits, flash LED's, whatever
goto main

As long as main takes less then 333uS (for a 1.5K period) you will never miss a beat, and I don't think you can get any faster

[HankMcSpank]

Hi Bert,

Apologies for the delay in coming back..... I don't really want to trigger an interrupt on every zero cross, as that will bog things down (there'll be heaps of them)...even though my main isn't doing much...it may get bigger & I'm still reeling from a similar thing with cap touch interrupts (basically to have a cap touch sensor feel 'zippy' you've got to generate a lot of interrupts ....I found to my cost how having a fairly modest interrupt rate quickly brought my main loop to its knees!)

I'd rather not go with the zero cross/switch close detect in the main loop, because as mentioned, it's not doing much at the moment...but I'm a terrible one for lobbing things into my main & making it bloaty in short order ...at least an interrupt will get priority no matter I may/may not do in my main!

Many thanks for everyone's input.