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???
06/26/07 06:15
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 		 #141254 - Hardware design
Responding to: ???'s previous message
My hardware design for probable serial keyboard is

4x6 MATRIX KEYPAD------IIC(I2C)DEVICE PCF8575---------MCU
SDA connected to INT0
SCL connected to T0

any key pressed on 24 key keypad will generate respective 16-bit code .This code will be sent to MCU by 8575.Now the question is

1)have I to latch 16-bit data for 8575
2)what will interrupt routine
3) How to store 16-bit data in 89c51 (may use two loops of 8-bits storage)
4)How to handle SCL for data transfer (have reffered datasheet)



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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