I want to add a 4x4 keypad to a 16F877A, i've made the connections to the pins but I don't know how to decode/write the ASM code.
What I want to do is: when I press 3 on the keypad the PIC will scan the keypad and figure it out it was the '3' key and load it in a variable.
So far I wrote the code for:
; RB4 RB5 RB6 RB7
; COL1 COL2 COL3 COL4
; RB0 ROW1 1 2 3 A
; RB1 ROW2 4 5 6 B
; RB2 ROW3 7 8 9 C
; RB3 ROW4 * 0 # D
Setting the pins to the wires.
How to intercept the key pressed ?!
I couldn't find anything on the net that will explain the logistic or how is done step by step.
Could anyone help with a source code explained or some good documentation?