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???
07/02/04 23:44
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 +2 Underrated		 #73556 - RE: key pad verification at boot up time
Responding to: ???'s previous message
Raghunathan said:
1. Reserve two pins (A, B )in the connector.
2. Short them ( loop them )both on the keypad side.
3. Connect A to a port pin and B to ground on MCU side of connector.
4. Poll the port pin to know if the key pad is connected.

Farhan Arshad said:
Can u (sic) explain all the points in more detail.

Raghu has already given you a pretty clear & complete description - you want even more, and yet you can't even be bothered to to type "you" properly!

What Raghu's saying is:
Save This Code
-----------+
8051       |
           |
  Port Pin +----------> A >--+
           |                 |
           |       +--> B >--+
           |       |
           |      -+-
           |      GND
           |
    other  +---------->   >---
    keypad :          :   :     to key
    port   :          :   :     matrix
    pins   +---------->   >---
           |
-----------+
You will need a pullup on the port pin; it should be clear that the port pin will then be high unless the keyboard is connected

List of 7 messages in thread
TopicAuthorDate
key pad verification at boot up time            01/01/70 00:00      
   RE: key pad verification at boot up time            01/01/70 00:00      
      RE: key pad verification at boot up time            01/01/70 00:00      
         RE: key pad verification at boot up time            01/01/70 00:00      
            RE: key pad verification at boot up time            01/01/70 00:00      
   RE: key pad verification at boot up time            01/01/70 00:00      
      RE: key pad verification at boot up time            01/01/70 00:00      

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