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???
06/23/05 03:59
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 		 #95668 - Port 0 to Port 0.
Responding to: ???'s previous message
Tp Ow:

When board A is without power the 10K pullup resistor on the common wire ends up looking like a 10K ohm load into GND when viewed from the powered board B end. The two 10K resistors you have end up making a voltage divider and leave the logic signal at the board B input pin be at some voltage in the no-mans-land between Vil and Vih.

I would encourage you to crack out the oscilloscope to look at the signals to see what is happening. You would see right away what I am talking about.

Michael Karas


List of 49 messages in thread
TopicAuthorDate
Invalid input voltage?            01/01/70 00:00      
   read the specs            01/01/70 00:00      
      Re:read the specs            01/01/70 00:00      
         Noise margins            01/01/70 00:00      
            Re:Noise margins            01/01/70 00:00      
            MAKE the signal determinate            01/01/70 00:00      
   0 or 1            01/01/70 00:00      
      Fuzzy logic...?!            01/01/70 00:00      
         zone between VIL and VIH            01/01/70 00:00      
         zone between VIL and VIH            01/01/70 00:00      
            The 'grey' zone            01/01/70 00:00      
               Illogical signals help us to having...            01/01/70 00:00      
                  Well, I'm lost!            01/01/70 00:00      
                     Re:Well, I'm lost!            01/01/70 00:00      
                        Scopes            01/01/70 00:00      
                           Re:Scopes            01/01/70 00:00      
                     7 or 9 value logic            01/01/70 00:00      
                  I understand what Mehdi is saying.....            01/01/70 00:00      
                     Ah            01/01/70 00:00      
                     excellent, Michael            01/01/70 00:00      
                        triad            01/01/70 00:00      
                     wow, Mike            01/01/70 00:00      
                     There's the rub            01/01/70 00:00      
                     Detect What?            01/01/70 00:00      
                     Absolutely but!            01/01/70 00:00      
                        a question based on a guess            01/01/70 00:00      
               Not debounce. Hysteresis/schmitt            01/01/70 00:00      
                  Re:Not debounce. Hysteresis/schmitt            01/01/70 00:00      
                     Well, then ADC.            01/01/70 00:00      
         It Could be            01/01/70 00:00      
            "undefined operation"            01/01/70 00:00      
               Undefined            01/01/70 00:00      
                  Exactly            01/01/70 00:00      
   Thanks...            01/01/70 00:00      
      based on the above            01/01/70 00:00      
         Erik:Based on mehdi's emphasis            01/01/70 00:00      
            Thanks            01/01/70 00:00      
            Wow.            01/01/70 00:00      
               I describe it!            01/01/70 00:00      
                  Service            01/01/70 00:00      
                  I will never            01/01/70 00:00      
                     I will always            01/01/70 00:00      
            the missing if            01/01/70 00:00      
   Port 0 output when no power            01/01/70 00:00      
      Port 0 to Port 0.            01/01/70 00:00      
         Voltage Divder of 10k            01/01/70 00:00      
            nope            01/01/70 00:00      
               2 line solution            01/01/70 00:00      
                  I do somethimes my thumbs have another o            01/01/70 00:00      

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