Small Problem
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Posts: 46,084
You should use only one resistor: the pullup.
Low is read with direct contact with GND
ACJacques
At 17:07 11/02/02 +0000, you wrote:
>I am trying to detect whether an input pin is floating or shorted to
>ground. Right now I have a 10k pull-up resistor on the pin so I
>should normally read a HIGH and when it is shorted to ground I should
>read a LOW while pulling 500uA through the resistor. The problem is
>that when it is floating, there is only about 1.5V on the pin, not
>5V. Any suggestions as to how I could get it to read a high when the
>pin is floating?
>
>
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Low is read with direct contact with GND
ACJacques
At 17:07 11/02/02 +0000, you wrote:
>I am trying to detect whether an input pin is floating or shorted to
>ground. Right now I have a 10k pull-up resistor on the pin so I
>should normally read a HIGH and when it is shorted to ground I should
>read a LOW while pulling 500uA through the resistor. The problem is
>that when it is floating, there is only about 1.5V on the pin, not
>5V. Any suggestions as to how I could get it to read a high when the
>pin is floating?
>
>
>To UNSUBSCRIBE, just send mail to:
> basicstamps-unsubscribe@yahoogroups.com
>from the same email address that you subscribed. Text in the Subject and
>Body of the message will be ignored.
>
>
>Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
Comments
ground. Right now I have a 10k pull-up resistor on the pin so I
should normally read a HIGH and when it is shorted to ground I should
read a LOW while pulling 500uA through the resistor. The problem is
that when it is floating, there is only about 1.5V on the pin, not
5V. Any suggestions as to how I could get it to read a high when the
pin is floating?
consigli@p... writes:
> I am trying to detect whether an input pin is floating or shorted to
> ground. Right now I have a 10k pull-up resistor on the pin so I
> should normally read a HIGH and when it is shorted to ground I should
> read a LOW while pulling 500uA through the resistor. The problem is
> that when it is floating, there is only about 1.5V on the pin, not
> 5V. Any suggestions as to how I could get it to read a high when the
> pin is floating?
>
Make sure your pin is in INPUT mode and then double check. It is possible
the pin is damaged. Test your circuit on another pin to confirm.
-- Jon Williams
-- Parallax
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