H Paul,
Thank you very much for your input - truthfully, I was was getting too wrapped up in this over the weekend, but after drawing a blank with every avenue explored, I'm taking a self enforced mini break from that particular problem (I often find coming back to a project after a rest sparks new ideas & approaches). re your specific idea...I'll freely admit that I'm sort of out my depth when it comes to the inner working of interrupts (ie Picbasic interrupts vs ASM interrupts vs DT interrupts), but at one stage I do recall getting intensely intimate with the datasheet & having a "what the hell" pop at something *very* similar to what you mention - I saw no difference (but I will revisit in the light of your input)
I could really do with some interrupt big hitters to chime in & outline a little a bit about how to get such time sensitive interrupt timings down to the bare minimum (assuming your suggestion isn't the only attack) ....becuase as it stands right now, I have *NO* (zilch, nada, zero, scratch) idea why that comparator2 interrupt count will not register below 336 when I feed a very slightly phase lagged signal into comp2 ...and alas, the my future (parked) status as a multimillionaire who invented widget X depends on getting that count to reflect the time lag between comp1 & comp2 tripping
I'm in part slightly reticent to even push this one too much in the (highly possible) case there's something inherently wrong in my PIC /PICBasic approach - what I am convinced about is that the inputs to the comparators are without question correct - I may be pants at programming, but I know how to drive a scope, sig gen etc! (I think my youtube video illustrates the issue seems to be a valid one)
if anyone out their in the global 'PIC interest land' feels up to the challenge - they could see themselves what happens when they feed near identically phased signals (ie a clock?) into comparator1 & comparator2 (that said an identical signal might cause problems with a race scenario?...but I concede that most don't have the faciilities or interest to setup an all pass to phase shift the two signals!)...in principle, with identical (phase) signals into both comparators, the count for comparator 2 ought to be very close to zero (like single digits)
But I will come back to this (& first on the list will be your suggestion..if for no other reason thatn your is the only suggestion I have, lol) - I'm presently now working on Project Y - it's not gonna be the blockbuster that Widget X will be ...but got to keep keep my kids in Nike trainers somehow or other
Edit: While I'm publicily declaring my woeful lack of grasp of time sensitive h/w & corresponding code....I also wonder if changing my PIC might help to get that comp2 count down? (I'm using a 16F690 not becuase it's necessarily the most suitable - but it came bundled with my PIKIT2 starter kit & I've stuck with it from new and have started to get the hang of it a little - when your grappling in the dark as often as am, you need a torch that's familiar!), but I see a chart like this http://www.microchip.com/en_us/technology/xlp/ & then wonder, is there a more efficient PIC for doing this type of stuff out there...??? (eg pics optimised for single instructions - not even sure what that means but the bar chart looks like a shocker!)
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