Camera interference from Serial Com (RS-232)

Discussion in 'Programmer's Corner' started by MCrowe, Sep 11, 2011.

  1. MCrowe

    Thread Starter Member

    May 29, 2011
    69
    0
    OK, I know, prob not really where this sort of questionj should be posted, but everyone in this section has given me such good answers before...

    So, I have set up Serial com (RS-232) between two Pics (16f877a), using max232 chips. And I am running a communication line between the pics, about 30m. One end, I will call the Master is where you have all you controls, the other end, 'slave' has some motors and servos and cameras. Now, my problem is that when the com line is plugged in, I get annoying interference on the screen from my camera. If I unplug the com line, it goes away. I have tried all sorts of things but can't sort this out.

    Does any one have any experience with cameras? I am only running 4 wires for the tether. 12V, Ground, Com, and video. The video intereference looks like what I believe is called 'hum' and from what my research has turned up appears to be caused from having a 'ground loop'. But without much experience in this sort of thing I'm not sure what causes a 'ground loop'. Is there any way, software or hardware wise I could get rid of this? I can't just use serial com without the max232 over 30m can I? Would the problem be from the max232 switching from +12 to -12? AND is it alright to have only one ground wire? For Com, Camera, and servos? Also, to fix it, is there something I could add into one of the lines?
     
  2. MCrowe

    Thread Starter Member

    May 29, 2011
    69
    0
    So... too off topic for the programmers corner? What about if I word it a little different? Is it possible to change the communication to something other than RS-232 using a MAX323. I suspect the +-12v is not that healthy for the video signal. Or do I ned RS-232 to communicate over 30m? Any who, if any one has any suggestions that would be fantastic. Thanks all.
     
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