Zero cross detect - switching audio

[HankMcSpank]

Close enuff is probably using Logic 0 on a falling edge to trigger the switch.

:-)

Bert, ok...just sussed, where you came up with the 333us number!

1.5khz maximum audio frequency expected = 1/1500 = 660us period .....therefore half a period would be 333us.

so 'zero cross to signal peak' (90 degrees) at that frequency would be about 150us..... if I can get within 10% of zero @1.5Khz I'd be very happy.

If I run the PIC at 16Mhz, I reckon I ought to be get reasonably close to zero - even at the maximum expected audio frequency of 1.5Khz - in my mind, 15us is a chunky amount of 'window' to get an audio IC switch after the PIC's comparator has toggled?