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???
10/22/07 14:22
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#146010 - Assumption
Responding to: ???'s previous message
Erik Malund said:
b) your baudrate will be severely limited since you are relying on a rsistive pullup of a a signal loaded by cable capaitance.

He hasn't actually stated what chip he's using - maybe it has (the option of) push-pull drive...?

A 'cheap' method allowing a limited baudrate would be to use a buffer chip (e.g. a '126) for TxD and a schmitt (such as 2 HC14s in series for the RxD.

Also has the advantage of providing at least some protection for the processor pins against "abuse" on the line...



List of 27 messages in thread
TopicAuthorDate
UART Maximum            01/01/70 00:00      
   Baud rate ?            01/01/70 00:00      
      Baud            01/01/70 00:00      
   RS232?            01/01/70 00:00      
      100m on 4800 BPS            01/01/70 00:00      
         How?            01/01/70 00:00      
            true RS232            01/01/70 00:00      
   you do not say how            01/01/70 00:00      
      a) ----- option only            01/01/70 00:00      
         Twisted Pair            01/01/70 00:00      
            He would not be THAT ignorant, I hope            01/01/70 00:00      
         a much better idea            01/01/70 00:00      
            Assumption            01/01/70 00:00      
               a much better idea            01/01/70 00:00      
                  WRONG            01/01/70 00:00      
                     panacea ---> The Godess of all cure :)            01/01/70 00:00      
                        of course, you need to connect gnd            01/01/70 00:00      
                           ground problem isnt a problem            01/01/70 00:00      
                              Call a spade a spade...            01/01/70 00:00      
                              no, it is not            01/01/70 00:00      
                                 Differential            01/01/70 00:00      
                                    no, it is not            01/01/70 00:00      
                                       Oh yes it is!            01/01/70 00:00      
                                       since you control both ends ...            01/01/70 00:00      
                                          Minimum RS422/485            01/01/70 00:00      
                                             mimum length for 485/422            01/01/70 00:00      
                                                Thanks for the input to all            01/01/70 00:00      

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