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???
08/22/06 03:39
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 		 #122749 - Try this one
Responding to: ???'s previous message
Tercio said:
A difference is thah i put a pull ups of 4.7K Ohms in ins and outs of buffer.

To achieve what? With many printer ports pull-ups are not at all suited to make a CMOS signal from TTL, because they use a 3.3V supply, like mine! You cannot increase the signal level by pull-ups then!! This is a typically made mistake, "solving" a problem by making false assumptions... Forget pull-ups in combination with a printer port, do only use a 74LS244 compatible buffer to handle printer port signals.

Have a look at this thread:

http://www.8052.com/forumchat/read.phtml?id=122673

Kai

List of 53 messages in thread
TopicAuthorDate
AT89s52 error with programmers            01/01/70 00:00      
   the 'weekly' question get the weekly answer            01/01/70 00:00      
   Add some pull up resistors (4.7K\'s) on LS device.            01/01/70 00:00      
      risque business            01/01/70 00:00      
   Home made JTAG            01/01/70 00:00      
      It is so refreshing to see thing like this instead            01/01/70 00:00      
         Tested!            01/01/70 00:00      
            have you 'tested' that the flash caps are fully            01/01/70 00:00      
               Atmel does that            01/01/70 00:00      
                  I think you are wrong            01/01/70 00:00      
                     I don't think so            01/01/70 00:00      
                        yes, and no            01/01/70 00:00      
                           Bah, shoot that designer :-)            01/01/70 00:00      
                              not the chip designer            01/01/70 00:00      
                                 JTAG x Flash Data Retention            01/01/70 00:00      
                                    nope            01/01/70 00:00      
   Tnx for answers...!            01/01/70 00:00      
   89s52 programmer            01/01/70 00:00      
      Only LS chips            01/01/70 00:00      
         there is the mail            01/01/70 00:00      
            here is world´s end            01/01/70 00:00      
               However far it from nowhere, I am sure you have ma            01/01/70 00:00      
                  You can buy here!            01/01/70 00:00      
                     he can do it himself...            01/01/70 00:00      
            What more fast than 9 ns?!            01/01/70 00:00      
               I do not understand. What I said is not to find s            01/01/70 00:00      
         Then stop doing in electronics!            01/01/70 00:00      
   re: AT89S52 error            01/01/70 00:00      
   Somebody test buffer CD4010?            01/01/70 00:00      
      the CD40 is sloooooooow compared to HC            01/01/70 00:00      
         What more fast than 9 ns?!            01/01/70 00:00      
            Not the speed is reason only            01/01/70 00:00      
   But and the pull ups in buffer´s out?            01/01/70 00:00      
      Does that suggest anything to you?            01/01/70 00:00      
      Type "74VHC244" into the search window            01/01/70 00:00      
         show the calculations            01/01/70 00:00      
      Schematic of programmer using 74LS244            01/01/70 00:00      
         Circuit that i am using            01/01/70 00:00      
            the very reason            01/01/70 00:00      
               Right...!            01/01/70 00:00      
                  have you conmsidered a 'radical' approach            01/01/70 00:00      
                     RX2...?!            01/01/70 00:00      
                        Rx2            01/01/70 00:00      
            Try this one            01/01/70 00:00      
               a full circle            01/01/70 00:00      
                  Time for a decision...            01/01/70 00:00      
               I did it...!            01/01/70 00:00      
                  Can\'t you order the parts by mail?            01/01/70 00:00      
      the old STUPID "It is tested"            01/01/70 00:00      
         Gee, another BS answer from Erik.            01/01/70 00:00      
            I can BE QUITE specific about what I post            01/01/70 00:00      
         "tested" does not mean tested            01/01/70 00:00      
            and even then ...            01/01/70 00:00      

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