Zero cross detect - switching audio

[HankMcSpank]

Inside ISR, wait for the signal to cross zero (in either direction, max time here would be .3333mS?)

Hi Bert...thanks for the confirmation - yes, you understand what I'm trying to do ...what I would add at this point is the full sequence of events really needs to be like this...

1. Switch gets pressed
2. IOC interrrupt routine Entered

hang around at this point, until....


3. comparator toggles (zero cross) -> Audio switch control voltage get's 'enabled' as quickly as possible thereafter.

hang around at this point, until....

4.Switch gets released (finger removed!)
5. comparator toggles (another zero cross)-> Audio switch control voltage get's 'disabled' as quickly as possible thereafter.
6. exit the IOC switch interrupt routine.

where did your .333mS number come from?

I don't need to trap the initial switch press too quick (anything sub 4mS will likely be ok), but from the comparator flipping state to the audio switch control voltage changing needs to be as blisteringly fast as I can make it (as obviously, the longer this bit takes the 'further' the AC signal is going to be away from 'zero') ..... 333us seems like a long time!