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Arduino Input pin Mode

Former Member

I would like to know, if a pin needs to be used as an input, is it necessary to use

 

digitalWrite (pin,HIGH).

 

 

Is it better to define the pin to be used as input as an integer type or using #define ??

 

 

The reason why I'm asking is, I need to send a message whenever, pin 9 become high (or low) , but the problem, I'm facing is that the message is sent as soon as the program is uploaded to the board.

 

Pls help!!!

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  • If a pin is input, wouldn't you want to read it's state rather than attempt to write to it? I agree with Mark - a little show and tell could help.

     

    ~Gtr_Stitch

  • in reply to Former Member

    Please see my comments at http://arduinoadventurer.wordpress.com/errata/ .

     

    The OrigPoster is entirely correct!

     

    digitalWrite (pin,HIGH) is a completely wrong headed way of doing what may be needed.

     

    pinmode(pinX,  INPUT_PULLUP);  is by far the preferred rational syntax when wanting to activate the chip's internal pullup resistor.

     

    Step by Step:

         pinmode(pinX,  INPUT_PULLUP);

         watch for a logic zero on pinX

         send message when logic zero is detected

     

    The alternative is what Mark said.  Using an external pulldown resistor:

         pinmode(pinX,  INPUT);

         watch for a logic one on pinX

         send message when logic one is detected

                       

    Hope that helps.

    -=SyntaxMatters=-

    Happy Trails

Reply
  • in reply to Former Member

    Please see my comments at http://arduinoadventurer.wordpress.com/errata/ .

     

    The OrigPoster is entirely correct!

     

    digitalWrite (pin,HIGH) is a completely wrong headed way of doing what may be needed.

     

    pinmode(pinX,  INPUT_PULLUP);  is by far the preferred rational syntax when wanting to activate the chip's internal pullup resistor.

     

    Step by Step:

         pinmode(pinX,  INPUT_PULLUP);

         watch for a logic zero on pinX

         send message when logic zero is detected

     

    The alternative is what Mark said.  Using an external pulldown resistor:

         pinmode(pinX,  INPUT);

         watch for a logic one on pinX

         send message when logic one is detected

                       

    Hope that helps.

    -=SyntaxMatters=-

    Happy Trails

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