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???
02/28/08 16:02
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#151604 - Paranoia medicine
Responding to: ???'s previous message
So, you could put a Schmitt trigger gate of 74HC14 directly at the sensor, using a pull-up of 4k7, unless the data sheet intervenes. At microcontroller side another 74HC14 gate could act as a receiver. Now you can also place some filtering in front of receiver in order to remove noise or to protect against ESD, etc.

Even better, you could put a RS-485 transmitter directly at the sensor, using a pull-up of 4k7, unless the data sheet intervenes. At microcontroller side a RS-485 receiver would be the receiver. Now, using modern 485 chips you will have "protection against ESD" and with differential signalling you will be virtually immune to noise.

Erik

List of 40 messages in thread
TopicAuthorDate
P3.5 input problem            01/01/70 00:00      
   100k is way too large            01/01/70 00:00      
      Yup            01/01/70 00:00      
      ports1-3 vs. port0            01/01/70 00:00      
      a small correction            01/01/70 00:00      
   Page 4 datasheet says            01/01/70 00:00      
      Calculating the maximum resistor            01/01/70 00:00      
         Calculating the ...            01/01/70 00:00      
   80uA is not a maximum specification            01/01/70 00:00      
      re:resistor            01/01/70 00:00      
   Resistor            01/01/70 00:00      
      I would not            01/01/70 00:00      
         Resistor            01/01/70 00:00      
            Resistor ... again ...            01/01/70 00:00      
      basic troubleshooting first            01/01/70 00:00      
         the sensor and its application            01/01/70 00:00      
            Oh, max frequency is ~4kHz :-)            01/01/70 00:00      
         Please ignore the "basic troubleshooting"            01/01/70 00:00      
         pray tell why            01/01/70 00:00      
            Capacitance problems ...            01/01/70 00:00      
   You have totally misunderstood the situation            01/01/70 00:00      
      thank you Kai            01/01/70 00:00      
         maybe it is            01/01/70 00:00      
            Link in original post            01/01/70 00:00      
            datasheet            01/01/70 00:00      
         Being paranoid is a good attitude...            01/01/70 00:00      
            Paranoia medicine            01/01/70 00:00      
               Yes, perfect, i also thought about this...            01/01/70 00:00      
                  the "industrial strength" 485 transciever            01/01/70 00:00      
                     But they gaurantee this            01/01/70 00:00      
      But the micro port shouldn't be driving anything            01/01/70 00:00      
         Missing the boat.            01/01/70 00:00      
            Waving at the boat.....            01/01/70 00:00      
               wrong place (in some instances)            01/01/70 00:00      
            More about the P3.5 pull-up issue            01/01/70 00:00      
               one simple way            01/01/70 00:00      
               AT89S8252            01/01/70 00:00      
         Please read this...            01/01/70 00:00      
   ABS & Safety            01/01/70 00:00      
      safety concerns            01/01/70 00:00      

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