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???
08/01/05 15:09
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 		 #98610 - which optocouplers
Responding to: ???'s previous message
hi,

Shivani Saini said:
i am using optocoupler to pull down pins of 165 there is 0.7volts when opto pulls it low.
shivani


Oops, this is another case! Depend on optocoupler and your schematic (Vcc, pull-ups etc) its response time may grow up to 100us. I think you should either use fast-response optocouplers or instert much more NOPs into the code.

Regards,
Oleg

List of 28 messages in thread
TopicAuthorDate
74hc165 read problem            01/01/70 00:00      
   pull ps?            01/01/70 00:00      
      external pull up            01/01/70 00:00      
   74LS165 schematic and assembly program            01/01/70 00:00      
      re 74LS165 schematic and assembly progra            01/01/70 00:00      
   connections and timings            01/01/70 00:00      
      Port0 can show very high rise times            01/01/70 00:00      
      thanks oleg and kai            01/01/70 00:00      
      re connections and timings            01/01/70 00:00      
         What pull-ups?            01/01/70 00:00      
            Also....            01/01/70 00:00      
               re also            01/01/70 00:00      
                  Very strange...            01/01/70 00:00      
                     re Very strange...            01/01/70 00:00      
                        Something wrong with 74HC165?            01/01/70 00:00      
                           If you have an oscilloscope..            01/01/70 00:00      
                              re If you have an oscilloscope..            01/01/70 00:00      
            re What pull-ups?            01/01/70 00:00      
               HC vs HCT vs TTL            01/01/70 00:00      
   165 access problem            01/01/70 00:00      
   using opto to pulldown pin of 74hc165            01/01/70 00:00      
      which optocouplers            01/01/70 00:00      
      time for schematics            01/01/70 00:00      
   here is solution            01/01/70 00:00      
   it is working            01/01/70 00:00      
      because of something in your hardware            01/01/70 00:00      
         nop not due to hardware            01/01/70 00:00      
            still could be            01/01/70 00:00      

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