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.