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???
02/28/05 02:39
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#88596 - connecting a keypad
Responding to: ???'s previous message
Yogesh:
Here is the basic scheme to attach a keypad to a microcontroller. This example shows a 16 key matrix organized as 4 rows by 4 columns. The example shows port 1 being used. As shown the software would scan the rows as outputs, one at a time being low and then monitor on the column pins as inputs. The resistors keep the column pins high when there is no low from a row output via a closed switch.



You could look at the various software source codes on this web site for a sample of how to implement a keypad scanning algorithm. Here is a link to some C code I posted a while back. Note that in that example the "rows" and "columns" are interchanged with regard to which set of 4 pins are the outputs and which 4 are used to monitor as inputs.

Karas's Keypad Scanner Code In C

Michael Karas




List of 10 messages in thread
TopicAuthorDate
Connecting LCD and Keypad to 8051            01/01/70 00:00      
   No problem            01/01/70 00:00      
      Beats me.            01/01/70 00:00      
         74C992            01/01/70 00:00      
            Will the real encoder please stand up...            01/01/70 00:00      
               Part Cost            01/01/70 00:00      
                  Or One Part.....            01/01/70 00:00      
   Connecting LCD & Keyboard            01/01/70 00:00      
      connecting a keypad            01/01/70 00:00      
      selling antiques as new            01/01/70 00:00      

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