Thread: 4x4 keypad problems

Hi, I have a keypad 74C922 encoder and a pic18f4520.
how do i integrate it into my c program??
it must be able to recognize numbers in sequence eg.1-2-3-4

Originally Posted by data sheet

Each of the PORTB pins has a weak internal pull-up. A
single control bit can turn on all the pull-ups. This is
performed by clearing bit, RBPU (INTCON2<7>). The
weak pull-up is automatically turned off when the port
pin is configured as an output. The pull-ups are
disabled on a Power-on Reset.

Originally Posted by data sheet

Four of the PORTB pins (RB<7:4>) have an interrupton-
change feature. Only pins configured as inputs can
cause this interrupt to occur (i.e., any RB<7:4> pin
configured as an output is excluded from the interrupton-
change comparison).

Originally Posted by data sheet

The interrupt-on-change feature is recommended for
wake-up on key depression operation and operations
where PORTB is only used for the interrupt-on-change
feature. Polling of PORTB is not recommended while
using the interrupt-on-change feature.

Link to a similar discussion on the Microchip forum: How to interface 4x4 keypad with PIC microcontroller

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