ROW0          =>       PIN_X0
ROW1          =>       PIN_X1
ROW2          =>       PIN_X2
ROW3          =>       PIN_X3
COL0          =>       PIN_X4
COL1          =>       PIN_X5
COL2          =>       PIN_X6
COL3          =>       PIN_X7

     R  ROW0  {'1' ,'2' ,'3' ,'A'}
     R  ROW1  {'4' ,'5' ,'6' ,'B'}
     R  ROW2  {'7' ,'8' ,'9' ,'C'}
     R  ROW3  {'*' ,'0' ,'#' ,'D'}
              COL0 COL1 COL2 COL3
               |    |     |   |
               R    R     R   R
               |____|_____|___|___+VCC
