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LM555 programming? — Parallax Forums

LM555 programming?

mikeweezermikeweezer Posts: 27
edited 2005-03-06 03:04 in General Discussion
Hello everyone,


I am trying to program my stamp to communicate with an LM555. The reason for this is that I don't want my output pins to get caught up in a PAUSE command. Can anyone give me an idea on how to do this?

Thanks,

Mike

Comments

  • KenMKenM Posts: 657
    edited 2005-03-06 02:15
    I assume you are using the 555 in "one shot" mode, correct?

    Operation is as follows:

    When the stamp pin brings R1 to ground, the 555·will·go high and stay high until it "times out".

    This will enable you to bring the stamp pin low, then immediately high again, allowing the stamp to go on with other tasks all the while the 555 being high until it times out.

    The 555 output will not go high again until the stamp pin goes high then low again.

    Some would suggest about 220 ohms between the stamp pin and R1. This would be to protect a momentary inrush current into the stamp pin when bringing the cap to ground.

    Post Edited (KenM) : 3/6/2005 3:05:35 AM GMT
    555_Single_Trigger.jpg
    217 x 179 - 6K
  • mikeweezermikeweezer Posts: 27
    edited 2005-03-06 02:41
    What do you mean by "times out"? I am looking for the LM555 it to stay high for about 2 seconds.

    Thanks!

    Mike
  • KenMKenM Posts: 657
    edited 2005-03-06 03:04
    What I meant by times out is the output pulse of the 555 going back to low after being high.

    In your case, 2 seconds elapsing.
    ·
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