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???
10/19/08 10:10
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 		 #159192 - Check the write waveform timings!!!!!
Responding to: ???'s previous message
Allow me to assume you are using AT89C51 microcontroller.
Then,
AT28C64B requires a minimum Write pulse width of 100ns.
AT89C51 operating at 12MHz clock would give a write pulse of somewhere in between 43ns to 123nS.
NB: if you are using faster devices then the case is even worse for AT28C64B.
Also i havint checked if there are any other discrepancy.
Solutions:-
1)Underclock AT89C51.
2)Try experimenting with different AT89C51 so that you get a part which has a write pulse width more than 100ns.
3)Device a write instruction yourself.

List of 41 messages in thread
TopicAuthorDate
MOVX doesn't work for writing.            01/01/70 00:00      
   It's a read-only memory            01/01/70 00:00      
      EEPROM            01/01/70 00:00      
         RAM-EPROM            01/01/70 00:00      
            That wouldn't be an EEPROM.            01/01/70 00:00      
            Look at Ferro-electric memory            01/01/70 00:00      
         Not wrong.            01/01/70 00:00      
            An EEPROM is an EPROM            01/01/70 00:00      
               Technically, but not in common usage of the term.            01/01/70 00:00      
                  Common use != Definition            01/01/70 00:00      
               Not quite ...            01/01/70 00:00      
                  No, it's not            01/01/70 00:00      
                  A datasheet that actually calls it a "UVEPROM"            01/01/70 00:00      
                     OK ... I stand corrected ...            01/01/70 00:00      
                        A link with EPROM <= EEPROM            01/01/70 00:00      
                        Not that generic!            01/01/70 00:00      
                           Magnetic core memory            01/01/70 00:00      
                           it is SERIAL EEPROM            01/01/70 00:00      
                              UVEPROM?            01/01/70 00:00      
                                 I think a part number would be the solution            01/01/70 00:00      
                                    Symmetric speed too.            01/01/70 00:00      
                           ta paidia paizei !!!            01/01/70 00:00      
            EEPROM implies EPROM            01/01/70 00:00      
               Today, it's the other way round.            01/01/70 00:00      
                  assumption < implication            01/01/70 00:00      
                  You missed the point!            01/01/70 00:00      
                     As one of my old tutors used to say...            01/01/70 00:00      
         Let's not confuse things further            01/01/70 00:00      
            You have also missed the point            01/01/70 00:00      
      Or...            01/01/70 00:00      
   Some Kind Like....            01/01/70 00:00      
      Non-Volatile Memory            01/01/70 00:00      
         or maybe the AT28C64B will work            01/01/70 00:00      
      You mean you want an NVRAM?            01/01/70 00:00      
   write eeprom            01/01/70 00:00      
      that may not be the problem            01/01/70 00:00      
         EPROM has special write-procedures            01/01/70 00:00      
   Check the write waveform timings!!!!!            01/01/70 00:00      
      How?            01/01/70 00:00      
         Source code to simulate MOVX...            01/01/70 00:00      
         Start with the datasheet ...            01/01/70 00:00      

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