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???
03/17/12 15:12
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#186752 - Being pedantic.
Responding to: ???'s previous message
Kai,

Mehdi has never specified 'how' precise the half-way voltage should be.
I got slated for saying that 'most' 8051 ports 'may' have external pull-up arrays.

A strong external resistor will regularise a weak internal pull-up.

Of course an external DAC or op-amp will give a more accurate result.
My money is on Mehdi not requiring perfect values in the first place.

David.

List of 21 messages in thread
TopicAuthorDate
Making a pulse with 3 different voltage level!            01/01/70 00:00      
   No best but consider a voltage divider            01/01/70 00:00      
      derivative with a DAC?            01/01/70 00:00      
   derivative with configurable ports            01/01/70 00:00      
   Thanks Per And Erik            01/01/70 00:00      
      which derivative            01/01/70 00:00      
      with an OPamp            01/01/70 00:00      
         Thanks Erik            01/01/70 00:00      
      So, you need to make -15V, 0V and +15V?            01/01/70 00:00      
         Hi Dear Kai            01/01/70 00:00      
         74hc series            01/01/70 00:00      
            FPGA            01/01/70 00:00      
      I think you can do it wih one resistor.            01/01/70 00:00      
         Most 8051 Systems?????            01/01/70 00:00      
            Well add a pull-up resistor then            01/01/70 00:00      
               Would prefer to not have to match internal resistors            01/01/70 00:00      
               You cannot match the weak internal active pull-up!            01/01/70 00:00      
                  Being pedantic.            01/01/70 00:00      
         Hi David            01/01/70 00:00      
   maybe a couple of mosfets ...            01/01/70 00:00      
      Thanks Richard            01/01/70 00:00      

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