I like this method...seems simple enough even for me to understand. Does
anyone have any comments about the method itself or changing the
leading/falling edge setting in the middle of the program? I'd assume
I'd have to disable the interrupt before I changed it. Can I change it
from inside the ISR?

Josh

Mahmood Elnasser wrote:
>
> You can set the interrupt on both rising edge and falling edge , first set
> it on rising edge , when the interrupt occurs set it on falling edge in the
> rising edge interrupt routine and vice versa  , I think I did my reception
> this way and I recall that the ir stream has a start bit of 20 us then 16
> bit code  then 16 bit key code , depending on your remote control of course
> . and the output is always hi the pulses are low. first you have to check
> that the start bit is the right length otherwise you just ignore the rest
> and the hi is 4 usec pulse and the low is 7 u sec , check it with a DSO or
> logic analyzer . if u keep the key on the remote pressed down you get just
> the start bit and 1 pulse  of certain duration and not the rest of the code
> , this is useful for things like volume up and volume down etc .
>
> ----- Original Message -----
> From: "Josh Koffman" <listsjosh@3MTMP.COM>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Sunday, December 02, 2001 9:56 PM
> Subject: [PIC]: What's the best way to decode IR?
>
> > Ok, since I can't seem to find anyone that's really done exactly what I
> > want to do, I seem to be forging new ground. Unfortunately, I'm not that
> > great at it, so I have a few questions. I plan on using one of the
> > little IR modules to decode the actual IR signal and give me a ttl out.
> > The question now is, what's the best way to deal with it?  I'd like to
> > stay away from just polling, because the PIC will be doing a bunch of
> > other things, and I don't want to run the risk of missing IR pulses. I
> > could use the external interrupt, so that every time there is a pulse
> > I'd check a TMR. The problem I see there is that I have to set the
> > interrupt to trigger on rising edge or falling edge, I can't do both. I
> > don't want to mess with portB interrupt on change. I was thinking I
> > could use the CCP module, but I don't really know how. I guess it would
> > trigger when it receives a pulse from the IR module, then captures the
> > value in the TMR. Then I could check the value of that against what my
> > high and low timings should be, and go from there. Again I think I run
> > into the rising/falling edge thing though. I'm really confused here. I'm
> > sure that there is a solution somewhere, I just can't quite figure it
> > out.
> >
> > If you have any ideas or suggestions, they will be appreciated!
> >
> > Thanks,
> >
> > Josh
> > --
> > A common mistake that people make when trying to design something
> > completely foolproof is to underestimate the ingenuity of complete
> > fools.
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> >
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> >
> >
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