Matrix keyboard with State Machine

[Ioannis]

Thanks to all!

Ioannis

[peterdeco1]

I did this a long time ago with a 4X4 membrane switch to play messages on an ISD chip.

Low PORTC.7
Pause 1
IF PORTB.4 = 0 Then MESSAGE1
IF PORTB.2 = 0 Then MESSAGE9
High PORTC.7

Low PORTC.6
Pause 1
IF PORTB.4 = 0 Then MESSAGE2
IF PORTB.2 = 0 Then MESSAGE10
High PORTC.6

Low PORTC.2
Pause 1
IF PORTB.4 = 0 Then MESSAGE3
IF PORTB.2 = 0 Then MESSAGE11
High PORTC.2

Low PORTC.1
Pause 1
IF PORTB.4 = 0 Then MESSAGE4
IF PORTB.2 = 0 Then MESSAGE12
High PORTC.1

Low PORTC.0
Pause 1
IF PORTB.4 = 0 Then MESSAGE5
IF PORTB.2 = 0 Then MESSAGE13
High PORTC.0

Low PORTA.0
Pause 1
IF PORTB.4 = 0 Then MESSAGE6
IF PORTB.2 = 0 Then MESSAGE14
High PORTA.0

Low PORTA.1
Pause 1
IF PORTB.4 = 0 Then MESSAGE7
IF PORTB.2 = 0 Then MESSAGE15
High PORTA.1

Low PORTC.4
Pause 1
IF PORTB.4 = 0 Then MESSAGE8
IF PORTB.2 = 0 Then MESSAGE16
High PORTC.4