Universal 4x4 keypad

Keypads

3 predefined keypads and one user definable keypad. Selectable binary, ASCII or key number.

Telephone keypad

1 2 3 A
4 5 6 B
7 8 9 C
* 0 # D

Calculator keypad

7 8 9 +
4 5 6 -
1 2 3 *
0 . E /

User defined keypad

7 8 9 /
4 5 6 *
1 2 3 -
C 0 = +

Interface

• RS-232
  • 16 to 43 478 Baud
  • Data out and inverted data out for generating standard RS-232 voltages
• SPI
  • 83 kHz with enable
• Parallel
  • 4 bit parallel output of key number
• MIDI

Misc

• Selectable beep/LED

Pin assignment

• RB0-3 = Keyboard row output/Parallel data output
• RB4-7 = Keyboard column input
• RA0 = DATA (RS-232, SPI, MIDI)
• RA1 = CLOCK (SPI)
• RA2 = ENABLE (SPI, Parallel)
• RA3 = Beeper/LED
• RA4 = Not connected

Connection diagram for keypad

If the keypad is 3 keys wide; leave RB7 disconnected.

RB0---X---X---X---X--
      |   |   |   |
RB1---X---X---X---X--
      |   |   |   |
RB2---X---X---X---X--
      |   |   |   |
RB3---X---X---X---X--
      |   |   |   |
     RB4 RB5 RB6 RB7