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???
05/18/06 05:54
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 		 #116462 - standard
Responding to: ???'s previous message
Richard,

why are so emotions?

There is word called "specification". This document indicates negative voltage requirement and it is good practice to follow standards. I hope that you do not ask yourself "why do I cross a street at green light only?", do you?

Once again: this is standard. It means that any vendor may rely on the fact of negative voltage presence. For example, it may be used as "line fail" detector: if at passive state there is no negative voltage then it means that line is broken.

More info about EIA/TIA may be found, for example, here: http://www.interfacebus.com/Design_Co...RS232.html

Regards,
Oleg

List of 68 messages in thread
TopicAuthorDate
hardware setup of AT89C51ED2            01/01/70 00:00      
   RTFM            01/01/70 00:00      
   board's setup            01/01/70 00:00      
   has been discussed            01/01/70 00:00      
   AT89C51ED2 in ISP            01/01/70 00:00      
      no 'unique' schematc needed            01/01/70 00:00      
      thanks joel            01/01/70 00:00      
    I sent for your email the schematic!            01/01/70 00:00      
   FLIP            01/01/70 00:00      
      sample code            01/01/70 00:00      
         program in assembly?            01/01/70 00:00      
            sample code in c            01/01/70 00:00      
   ISP without MAX232            01/01/70 00:00      
      that old gem again            01/01/70 00:00      
         A gem is always a gem            01/01/70 00:00      
            it does not help that you respond s..t a            01/01/70 00:00      
      Re: ISP without MAX232            01/01/70 00:00      
         To stop an urban legend ... seems imposs            01/01/70 00:00      
            just for the sake of argument ...            01/01/70 00:00      
               very clearly stated            01/01/70 00:00      
                  That's GREEN cheese!            01/01/70 00:00      
            from old time...            01/01/70 00:00      
               there you go            01/01/70 00:00      
               How about the 1488/1489?            01/01/70 00:00      
                  this all started with            01/01/70 00:00      
                     well, I read that, but ...            01/01/70 00:00      
                        but            01/01/70 00:00      
                           the standard still deserves a look            01/01/70 00:00      
            reminds me of the burden cap argument.            01/01/70 00:00      
         RS232 without -V explained            01/01/70 00:00      
            There is two ways to do things: by desig            01/01/70 00:00      
            Do never do            01/01/70 00:00      
               Answer in shematic of your post            01/01/70 00:00      
            I wouldn't rely on that ...            01/01/70 00:00      
               true, if you have no noise margin worrie            01/01/70 00:00      
                  What??? You imply the 1489 won't work?            01/01/70 00:00      
                     what is a 1489? and what is the issue            01/01/70 00:00      
                        it's what we used before the Max-xxxx            01/01/70 00:00      
                           who said 'require'?            01/01/70 00:00      
                              I think you're dreaming.            01/01/70 00:00      
                                 yes, I 'dream' noise immunity            01/01/70 00:00      
                                    and you're prepared to show ...            01/01/70 00:00      
                                       I can't            01/01/70 00:00      
                                          Try this link            01/01/70 00:00      
                                             I hope the datasheet is wrong            01/01/70 00:00      
                                                Nope, it isn't wrong ...            01/01/70 00:00      
                                                   Another gem? Well explained!            01/01/70 00:00      
                                                      so, now the crap is "justifued"            01/01/70 00:00      
                                                   hy do you keep beating a desd horse            01/01/70 00:00      
                                                      I'm not the one doing the beating            01/01/70 00:00      
                                                         I never said that            01/01/70 00:00      
                                                            Hysteresis, ... sure ...            01/01/70 00:00      
      Interesting ...            01/01/70 00:00      
          Just wait, next time it may very            01/01/70 00:00      
   you keep hammering 'needed'            01/01/70 00:00      
      No, in fact you haven't            01/01/70 00:00      
         standard            01/01/70 00:00      
            Of course I adhere to standards            01/01/70 00:00      
               I did not make the standard            01/01/70 00:00      
                  As long as you're arguing with me ...            01/01/70 00:00      
                     I directly quoted you, so who started th            01/01/70 00:00      
                        Erik, you need some practice            01/01/70 00:00      
                           That should settle it, you get your chip            01/01/70 00:00      
                        Chill brothers            01/01/70 00:00      
                           Time for a rendezvous            01/01/70 00:00      
                           to the two above            01/01/70 00:00      
                              Where's the science?            01/01/70 00:00      
                                 science            01/01/70 00:00      

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