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???
06/19/07 11:59
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 		 #141008 - rxd,txd
Responding to: ???'s previous message
1)there are on market numerical PC keypad - right part of
Your PC keyboard.
2)Get cheapest( or some with non-working keys) PC keyboard (5 USD) and open it - You will see
small board with MCU , connected to key matrix and to PCcable.
This is keyboard controller.
3)How You can make keypad? Well, If You can plane receiving from
"serial keypad" (google this), You can plane building of other device - 24 keys, 80c51, 5v regulator.
4)but if You have RX,TX and INTx pins free - simplest way is to
use shift registers and some procedure routine , which scans registers every 10 millisecond. Proble will be PCB, case ...


List of 36 messages in thread
TopicAuthorDate
Serial Keypad for 89c51            01/01/70 00:00      
   what is task ?            01/01/70 00:00      
      Task            01/01/70 00:00      
         use PCkbd controller            01/01/70 00:00      
            RXD and TXD            01/01/70 00:00      
               rxd,txd            01/01/70 00:00      
                  More keys            01/01/70 00:00      
                     What does it matter how many keys?            01/01/70 00:00      
               why not search the www?            01/01/70 00:00      
   I2C; 1-Wire            01/01/70 00:00      
   I2c            01/01/70 00:00      
      So now would be an excellent time to start!            01/01/70 00:00      
         let me complete            01/01/70 00:00      
            right now I need a hammer, but I do not have the            01/01/70 00:00      
               Erik            01/01/70 00:00      
                  I always have regretted            01/01/70 00:00      
                     OK Erik            01/01/70 00:00      
                        I2C or serial            01/01/70 00:00      
                           I2C is serial!            01/01/70 00:00      
                              Asynchronous nature of serial was on my mind!            01/01/70 00:00      
                           there is a philips appnote            01/01/70 00:00      
                           Hardware design            01/01/70 00:00      
                              too many haow-to ,but            01/01/70 00:00      
                              a better idea            01/01/70 00:00      
                                 Hardware I2C addresse            01/01/70 00:00      
                                    I2C is serial!            01/01/70 00:00      
                                       I meant UART            01/01/70 00:00      
                                          many, many flavours!            01/01/70 00:00      
                                    whatever you like            01/01/70 00:00      
                                    select Your own addresses            01/01/70 00:00      
                                       'wrong' is too strong            01/01/70 00:00      
                              Touch screen            01/01/70 00:00      
                                 sure            01/01/70 00:00      
                                 to the O/P ... Stick with one topic, please            01/01/70 00:00      
                                    No side track            01/01/70 00:00      
   Not much information            01/01/70 00:00      

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