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???
04/17/07 01:30
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Msg Score: -1
 -1 Message Not Useful		 #137350 - about P0
Responding to: ???'s previous message
on many 8051 microprocessors (and even microcontrollers), Port 0 is normally float.

It is fine to use them as general purpose data pins, but they really should be tied to a pull-up (or a pull down) resistor as well. 100K for a cmos chip will work well.

If you fail to do this, then there is a good chance that port 0 will float when the program is not running and chances are that there may be a problem using your LCD.

Why not try ports 1 and 3 instead?

List of 78 messages in thread
TopicAuthorDate
LCD Problem            01/01/70 00:00      
   stop shouting - also            01/01/70 00:00      
      Sorry Erik            01/01/70 00:00      
         no need to be 'sorry'            01/01/70 00:00      
            timing            01/01/70 00:00      
               delays aren't necessary if you monitor busy            01/01/70 00:00      
   Pullup resistors on P0            01/01/70 00:00      
      already answered            01/01/70 00:00      
   make sure            01/01/70 00:00      
      Is there any test procedure to test LCD Module?            01/01/70 00:00      
         from the shop            01/01/70 00:00      
   did you try...            01/01/70 00:00      
      tthat is SOME wait            01/01/70 00:00      
         ...            01/01/70 00:00      
            well, maybe is is a good thing            01/01/70 00:00      
               i need a lcd testing procedure            01/01/70 00:00      
                  like this            01/01/70 00:00      
                     lcd testing            01/01/70 00:00      
                        Couple of links            01/01/70 00:00      
                           no datasheet            01/01/70 00:00      
                              Should work the same...            01/01/70 00:00      
                                 +1 for this answer            01/01/70 00:00      
                                    LJMP limits            01/01/70 00:00      
      delays aren't necessary if you monitor busy            01/01/70 00:00      
      May be LCD is damaged!!            01/01/70 00:00      
         Pin 3 may require a negative voltage            01/01/70 00:00      
            PLEASE!!!!            01/01/70 00:00      
               There is a "convention"            01/01/70 00:00      
            to clarify?            01/01/70 00:00      
         two problems with the 'advice' you followed            01/01/70 00:00      
            Only lower line of LCD is showing!            01/01/70 00:00      
               looks like pretty normal behavior to me ...            01/01/70 00:00      
                  'cheap' -5 for a LCD            01/01/70 00:00      
   where is that standard?            01/01/70 00:00      
      It's not an EIA or a DIN standard ...            01/01/70 00:00      
         you said exactly that            01/01/70 00:00      
            We've all told him to read his LCD datasheet            01/01/70 00:00      
               this is getting ridiculous.            01/01/70 00:00      
                  ok, I deserve -1 from before            01/01/70 00:00      
                     why not spell it correctly            01/01/70 00:00      
                  That's why there are datasheets            01/01/70 00:00      
   LCD is workingggg!!!!!!            01/01/70 00:00      
      Now get to work            01/01/70 00:00      
         MISTAKES made            01/01/70 00:00      
   Datasheet, which created a problem.            01/01/70 00:00      
   Can LCD datasheet be uploaded for others referen.?            01/01/70 00:00      
      You have to get the correct datasheet            01/01/70 00:00      
         need lcd testing procedure            01/01/70 00:00      
            You need more data!            01/01/70 00:00      
               addendum to Richards post            01/01/70 00:00      
                  There is a de-facto standard            01/01/70 00:00      
                     lcd problem            01/01/70 00:00      
                        Disconnect d1            01/01/70 00:00      
                        problem with second line of lcd            01/01/70 00:00      
                           program            01/01/70 00:00      
                              your code has a problem?            01/01/70 00:00      
                                 looks like experimenting again ...            01/01/70 00:00      
                                 from hitachi data sheet on HD44780            01/01/70 00:00      
                                    I'm starting to hate these datasheets            01/01/70 00:00      
                                       BULL            01/01/70 00:00      
                                          get it RIGHT before you deviate from spec's            01/01/70 00:00      
                                       OK... I give up...            01/01/70 00:00      
                                    8 bit Initialization            01/01/70 00:00      
                                       lcd problem            01/01/70 00:00      
                                          program i used            01/01/70 00:00      
                                             driving voltage            01/01/70 00:00      
                                                its not the contrast problem            01/01/70 00:00      
                                                   why?            01/01/70 00:00      
                                                   Contrast and Initialization            01/01/70 00:00      
                                             you are, I hope, aware            01/01/70 00:00      
                                       That's the one...thanks            01/01/70 00:00      
   about P0            01/01/70 00:00      
      It shows that you "experiment" instead of reading            01/01/70 00:00      
      gibberish            01/01/70 00:00      
   small correction            01/01/70 00:00      
      thanks a lot            01/01/70 00:00      
         Thanks for informing us.            01/01/70 00:00      
            so, next time            01/01/70 00:00      

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