2 Replies Latest reply on Feb 16, 2012 4:20 AM by srinath.vardae

    interfacing keypad to psoc1

    srinath.vardae
    srinath.vardae Feb 16, 2012 7:29 AM

       I' ve been trying to write the code for a 8 by 7 keypad using polling method . The problem is that I have all the coloumns connected to 4.7K external pull up resistors. And I cant able to find out which drive mode to be set for both cols. & rows. I have tried every possible combination. Pls suggest which should be used and also pls verify my code. The project is attached below.  

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        • 1. Re: interfacing keypad to psoc1
          srinath.vardae
          srinath.vardae Feb 16, 2012 4:20 AM (in response to srinath.vardae)

           My only problem is I cannot able to make a key's  coloumn low and row high at the same time. Help me with the driving mode for the coloumn and row of the keys

          • 2. Re: interfacing keypad to psoc1
            user_1377889
            user_1377889 Feb 16, 2012 7:29 AM (in response to srinath.vardae)

            I would suggest not to use external resistors (if that is possible), otherwise you have a voltage divider between the internal pullup resistor and the external. This will result in a voltage that is neither High nor Low.

               

            Bob

               

             

               

            PS: I've posted some time ago a solution for a 3x4 matrix keyboard for PSoC3 and PSoC5. Just for your understanding have a look at it (with PSoC Creator 2.0) Search for "matrix" here or in the PSoCDeveloper forum.