How can I detect if pin is floating or shorted to ground?

Archiver

I just have a situation where an input port will either be shorted to
ground or floating. I need to monitor that to determine when it gets
shorted. Shouldn't be too tough, but I am new at this. Any help
would be greatly appreciated. Thanks

Archiver

Put a pull up resistor (say 10K or 22K) from +5V to the input pin. Now,
if the pin is floating, you will read a '1'. If the short to ground
occurs, the pin goes to '0' and you draw (at 10K) 500uA through the
resistor.

Al Williams
AWC
* Easy RS-232 Prototyping
http://www.al-williams.com/awce/rs1.htm



>

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Original Message

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> From: jconsiglio [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=B4Pld3ftE23B2sbPQNkn44wDxQCONPzRDR0ekdkpjjv1rHpHLMhugCrONlC-tk9FpkEmGqU1MXkdpQ]consigli@p...[/url
> Sent: Friday, February 08, 2002 9:31 PM
> To: basicstamps@yahoogroups.com
> Subject: [noparse][[/noparse]basicstamps] How can I detect if pin is floating or
> shorted to ground?
>
>
> I just have a situation where an input port will either be shorted to
> ground or floating. I need to monitor that to determine when it gets
> shorted. Shouldn't be too tough, but I am new at this. Any help
> would be greatly appreciated. Thanks
>
>
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