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Sony IR decode using hi-tech C for PIC16F877A Sony IR decode using hi-tech C for PIC16F877A
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Old 30th May 2009, 01:19 PM   #16
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Thanks guys. Good info'.

Is it important to measure the actual active-low portion of the signal or could you simply measure the time between active-low leading edges?

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Last edited by Mike, K8LH; 30th May 2009 at 06:43 PM.
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Old 30th May 2009, 01:38 PM   #17
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Quote:
Originally Posted by Mike, K8LH View Post
Thanks guys. Good info'.

Is it important to measure the actual active-low portion of the signal or could you simply measure the time from active-low leading edge to active-low leading edge?
It's important to measure the actual active-low time of each pulse, bear in mind it's not just a question of reading SIRC's, it's a question of rejecting all other types of IR signal.
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Old 30th May 2009, 01:54 PM   #18
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Knowing this info its real easy to create your own IR Protocol.

I think ill make one today. Ill call it AIRP or AIRC.

AtomSoft InfraRed Protocol
AtomSoft InfraRed Control

lol. Would be fun to do but would require a custom remote
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Old 30th May 2009, 03:11 PM   #19
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Jason,

I agree but one of the interesting aspects of this research is that I could use one of these very inexpensive "universal remotes" as the control head for some of my projects. There would be more unique key codes than I could ever possibly use.

Nigel,

Thank you for supplementing Pommie's and AtomSoft's excellent examples. I'd like to develop a simpler GetBit routine that qualifies each SIRC bit. Then I could decode the 12 bit style SIRC codes with a very simple routine like this;

Code:
;
;  the GetBit "blocking" sub' only returns on a valid SIRC bit
;
;    C = 1 for a valid <start> bit
;    C = 0 and Z = 1 for a '0' bit
;    C = 0 and Z = 0 for a '1' bit
;
GetSIRC
        call    GetBit          ; a qualified <start> bit?        |B0
        bnc     GetSIRC         ; no, branch, else                |B0
        clrf    irCmd           ; clear 'irCmd' variable          |B0
        bsf     irCmd,6         ; set counter bit for 7 bits      |B0
CmdLoop call    GetBit          ; get <data> bit in Z (C=0)       |B0
        skpz                    ; bit = 0? yes, skip, else        |B0
        bsf     irCmd,7         ; bit = 1                         |B0
        rrf     irCmd,F         ; collected all 7 'Cmd' bits?     |B0
        bnc     CmdLoop         ; no, branch, else                |B0
        clrf    irDev           ; clear 'irDev' variable          |B0
        bsf     irDev,4         ; set counter bit for 5 bits      |B0
DevLoop call    GetBit          ; get <data> bit in Z (C=0)       |B0
        skpz                    ; bit = 0? yes, skip, else        |B0
        bsf     irDev,5         ; bit = 1                         |B0
        rrf     irDev,F         ; collected all 5 'Dev' bits?     |B0
        bnc     DevLoop         ; no, branch, else                |B0
        return                  ;                                 |B0
I'm not sure a "blocking" type subsystem like this will work in most of my projects though so I think I might also research ways to make this a background task.

Thanks again for all the info' guys.

Mike
Last edited by Mike, K8LH; 30th May 2009 at 03:14 PM.
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Old 30th May 2009, 03:46 PM   #20
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A good while back someone emailed me an interrupt driven version of my original receiver code, I meant to add it to my tutorials, but forgot all about it - and can't seem to find it any more.

I'll keep looking.
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Old 30th May 2009, 04:01 PM   #21
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GetBit command would be simple. I would do the same as i did in C which was just wait for a Low or TRIGGER on low then count up until its high then calculate how long it took by reading the count variable. You should know how to do this already lol
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Old 30th May 2009, 04:27 PM   #22
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My code is exactly the same as yours Jason. I'm just having fun trying to make it a bit tighter, cleaner, simpler, and more elegant using assembler (my specialty, grin)...
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Old 30th May 2009, 04:41 PM   #23
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heh cool! I would love to see it when your done.
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Old 30th May 2009, 06:38 PM   #24
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FYI, found a C project with interrupt driven SIRC decoder as a background task which seems reasonably well done (using Interrupt on Change);

PIC RGB Power board with Infrared remote control
Last edited by Mike, K8LH; 30th May 2009 at 07:54 PM.
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Old 30th May 2009, 07:26 PM   #25
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To do SIRC in as background wouldnt be hard with my code. All you have to do is setup a interrupt and have it do the same code as in my "GetSIRC" function. Once you copy my code to the interrupt then you should be able to collect data like that. Just remove the first wait for low. Since it will interrupt on low anyway.
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Old 30th May 2009, 07:27 PM   #26
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ill try to create it in a minute. With a RBG LED with PWM just like that link just my own code
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Old 30th May 2009, 07:38 PM   #27
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Oh don't worry, I know how to unroll functions to make them work as part of an ISR (LOL).
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Old 30th May 2009, 07:42 PM   #28
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heh, i know your one smart dude. You correct me on a daily basis and im grateful. LOL
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