Connect two PICs?


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  1. #1
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    Default Connect two PICs?

    I have a situation where I need to connect two PICs. One is the 'master' and one is the slave. An output on the master goes to an input on the slave (weak pull-up enabled) and I only need to signal two states.

    My question is: Do I need a current limiting resistor on that line? I keep vacillating between the two answers, and thought I'd ask the experts.

    Thanks,

    Andy
    "I have noticed that even those who assert that everything is predestined and that
    we can change nothing about it still look both ways before they cross the street"


    -Stephen Hawking

  2. #2
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    Default Re: Connect two PICs?

    As long as you don't switch the slave pin to output you don't need a current limit resistor.

    /Henrik.

  3. #3
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    Default Re: Connect two PICs?

    Quote Originally Posted by HenrikOlsson View Post
    As long as you don't switch the slave pin to output you don't need a current limit resistor.

    /Henrik.

    That's kind of what I was leaning toward.

    Thanks Henrik
    "I have noticed that even those who assert that everything is predestined and that
    we can change nothing about it still look both ways before they cross the street"


    -Stephen Hawking

  4. #4
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    Default Re: Connect two PICs?

    Personally I would place a 4.7k resistor in series with each line connecting the two. That will limit the current to approx. 1 Ma. incase of the software or other malfunction you will not short ether processor pin to +5 volts or Ground.
    Dave Purola,
    N8NTA
    EN82fn

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