Comparator - tracking the high low condition more robustly.

[HankMcSpank]

I've set a PIC Internal comparator up to interrupt when a signal goes below a preset VRef level.

Here's what happens in the interrupt routine...

(in the code below, 'above_threshold' is a variable to monitor whether comparator is above or below the preset Vref threshold)

Comp1_Int:
@ INT_DISABLE CMP1_INT
If above_threshold = 1 then ; 
above_threshold = 0             
else 
above_threshold = 1
endif

@ INT_ENABLE CMP1_INT
@ INT_RETURN

Essentially it's toggling between a 1 or a 0 each time the comparator interrupts. (btw: please excuse the n00b type coding - is there a more elegant way to toggle a variable?)

Have I got the jist of how this should be approached? I'm actually now thinking as I've typed this out, that maybe the comparator only trips/interrupts in one direction?

It seems to be working, but occasionally it gets 180 degrees out of sync ...ie if the signal is above threshold it's variable is a 0 (wrong!) & if below it's a 1 (also wrong!)

How can I make this routine more robust?