• I/O mapping

    Hari Wiguna10/28/2014 at 02:24 0 comments

    D3, D4, D5, D13 are used by the LCD.
    D6..D9 are keyboard rows.
    A0..A3 are keyboard columns. I intentionally map these backward so the physical wiring would be pretty. :-)

    WARNING: Note that the LCD is 3.3V!!!

  • Figuring out the keypad

    Hari Wiguna10/28/2014 at 02:21 0 comments

    Using a multimeter, I deduced the rows and columns matrix of the keypad.
    Incidentally, there is as much as 2K resistance on they keypress, so I could not use the beeper on the multimeter.