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???
06/19/06 06:38
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 		 #118513 - Serial I/O Expanders
Responding to: ???'s previous message
As many have already said, 8255 is not a good choice. Search the forum for "Serial I/O Expander" and you will find good information. Many companies offer such devices. If hard to find in local market, you can use CD4094 like shift register for output exapnsion and CD4021 for input.

As Kai said, it is easy to route PCB for serial expanders than parallel ones since serial expanders can be cascaded for expansion and they require just 2 to 3 lines from micro.

You are doing an interesting project. What sensors you are planning to use to acquire traffic data?



List of 30 messages in thread
TopicAuthorDate
can P0 of c51input/output at same time            01/01/70 00:00      
   Why the 8255 ?            01/01/70 00:00      
      how to interface 8155            01/01/70 00:00      
         what does that have to do with this thread ?            01/01/70 00:00      
         Clearly, you should read the datasheet(s)            01/01/70 00:00      
   input/output            01/01/70 00:00      
      That's a very good put it!            01/01/70 00:00      
   Hints...            01/01/70 00:00      
      is 8255 really a bad idea???            01/01/70 00:00      
         Maybe            01/01/70 00:00      
            possibilities            01/01/70 00:00      
         Depends on your actual needs            01/01/70 00:00      
         Have you really considered the economics?            01/01/70 00:00      
            not all of us            01/01/70 00:00      
               the REAL question is ...            01/01/70 00:00      
                  answers            01/01/70 00:00      
                  8255 main drawback            01/01/70 00:00      
      Sorry, wrong link!            01/01/70 00:00      
      74HC595            01/01/70 00:00      
         As long as we must guess...            01/01/70 00:00      
            a little correction kai            01/01/70 00:00      
   Serial I/O Expanders            01/01/70 00:00      
      laser diodes/ldr sensors            01/01/70 00:00      
         Inductive loops            01/01/70 00:00      
            need little more info on inductive loop            01/01/70 00:00      
               Inductive loop            01/01/70 00:00      
                  basically an inductive loop is the same            01/01/70 00:00      
   I2C I/O expander            01/01/70 00:00      
      echo            01/01/70 00:00      
   60LEDs: MAX7219            01/01/70 00:00      

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