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???
07/06/11 06:12
Modified:
  07/06/11 09:04
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 		 #182809 - Totally missing the point
Responding to: ???'s previous message
Richard Erlacher said:
... serial memory ... certainly had both commands/status to/from the device and data from master to/from slave. IIRC, it had to be told on which edge to operate as well

But that has nothing to do with SPI itself - that is entirely specified by the slave in question.

it certainly wasn't like communicating with one or more '595 or '597 registers

SPI is just communicating with shift registers - nothing more!

Look again at the diagram on the Wikipedia page that you cited:


(for a read-only or write-only connection, the MOSI or MISO connection can be omitted)

It is just shift registers - there is nothing required that is not also required to use "discrete" shift registers.

Of course, if you were building a memory interface with "discrete" shift registers, you would still have to define your clock phasing (the SPI "mode"), and some "protocol" for reading the memory, writing the memory, and specifying the address(es) at which to read/write.

I simply don't see the advantage of using SPI

The advantage is that it is very widely used, so there is loads of support available.

There is no significant burden or disadvantage.



List of 49 messages in thread
TopicAuthorDate
problem rgarding uln and udn            01/01/70 00:00      
   They are different in every sense!            01/01/70 00:00      
      problem rgarding uln and udn            01/01/70 00:00      
         You forgot your links            01/01/70 00:00      
         Basic electronics            01/01/70 00:00      
            Clarification - more Basic Electronics            01/01/70 00:00      
            probelems regarding udn 2892            01/01/70 00:00      
               Still Basic electronics            01/01/70 00:00      
                  Links            01/01/70 00:00      
                     That'll be why he's still struggling after all these weeks!            01/01/70 00:00      
               open emitter            01/01/70 00:00      
                  Open collector            01/01/70 00:00      
         RE: i am not getting you            01/01/70 00:00      
   Did you really read datasheets?            01/01/70 00:00      
      problem rgarding uln and udn            01/01/70 00:00      
         relay matrix???            01/01/70 00:00      
         This doesn't make sense!            01/01/70 00:00      
            8x8 relay matrix?            01/01/70 00:00      
               relay matrix?            01/01/70 00:00      
                  not quite            01/01/70 00:00      
                  one interesting thing I learned            01/01/70 00:00      
               Unless...            01/01/70 00:00      
                  problem rgarding uln and udn            01/01/70 00:00      
                     lightning fast relays            01/01/70 00:00      
                        problems regarding uln and udn            01/01/70 00:00      
                           both            01/01/70 00:00      
                           None of this makes sense!            01/01/70 00:00      
                           It appears you need latching relays            01/01/70 00:00      
                              Latching relay is still slow            01/01/70 00:00      
                                 You're right, but the relay spec's should reveal that            01/01/70 00:00      
                              well, if he does ...            01/01/70 00:00      
                                 use toggle types ... they were around once ...            01/01/70 00:00      
                                    SPI + latched shift registers are good choices            01/01/70 00:00      
                                       The protocol is good ... but not necesary here            01/01/70 00:00      
                                          SPI is excellent for driving long shift registers            01/01/70 00:00      
                                             tell us, Per, what data types does SPI support?            01/01/70 00:00      
                                                Making Mountain Out Of Mole Hill            01/01/70 00:00      
                                                   protocol and/or command structure            01/01/70 00:00      
                                                No, SPI does *not* have both commands and data!            01/01/70 00:00      
                                                   Where you sit determines what you see            01/01/70 00:00      
                                                      Totally missing the point            01/01/70 00:00      
                                                         The major advantage            01/01/70 00:00      
                                                      Where Richard Sits......            01/01/70 00:00      
                                                         From where I sit...            01/01/70 00:00      
                                                      Always important to follow up the progress of technology            01/01/70 00:00      
                     Language barrier?            01/01/70 00:00      
                        Further question            01/01/70 00:00      
                     Sorry, double posting...            01/01/70 00:00      
   Cross-Post?            01/01/70 00:00      

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