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05/28/06 18:14
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 		 #117203 - passive matrix keyboard readout
hey guys

I'm looking for a passice way to read out a matrix keyboard. I know normally you keep scanning it but I do want it to react when I pres a key. So one way or the other trigger an interrupt and prosess the input without keeping my uC occupied.

does anyone have an idea?

it is an 4x4 matrix keyboard on a AT89S8253

regars
jeroen

List of 28 messages in thread
TopicAuthorDate
passive matrix keyboard readout            01/01/70 00:00      
   yep use the dallas switch debouncers            01/01/70 00:00      
      really, you can't have it both ways            01/01/70 00:00      
   Keypad            01/01/70 00:00      
      what???long weekend maybe            01/01/70 00:00      
         dedicated HW in some '51s            01/01/70 00:00      
   watch human reaction speed            01/01/70 00:00      
   derivative with interrupt on pin change            01/01/70 00:00      
      Or use a maxim 6816            01/01/70 00:00      
         I use SW debouncing...            01/01/70 00:00      
   Can reduce time spent in ISR Key Scan            01/01/70 00:00      
   Use tiny slave micro            01/01/70 00:00      
      Makes sense!            01/01/70 00:00      
         Programming the slave micro            01/01/70 00:00      
            $0            01/01/70 00:00      
               Non-zero cost            01/01/70 00:00      
                  who cares            01/01/70 00:00      
                     The folks who pay will care            01/01/70 00:00      
                        You apply what I said about apples to or            01/01/70 00:00      
                           you missed my meaning            01/01/70 00:00      
                              OK, I'll clarify            01/01/70 00:00      
            Costs? He needs to solve it anyway...            01/01/70 00:00      
               Tme is money            01/01/70 00:00      
                  contradictory            01/01/70 00:00      
         Key bounce.            01/01/70 00:00      
            use a LPC            01/01/70 00:00      
               any MCU will work            01/01/70 00:00      
                  with a LPC you can do either            01/01/70 00:00      

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