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7.4

Interface a 4x4 keypad with a PIC

Asked by navaru in Signal Processing, Programming Languages, Processor Programming for Specific Platforms

Tags: keypad, pic, 4x4

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?

Thanks for your time!
[+][-]12/05/07 11:23 PM, ID: 20417849Accepted Solution

Your question has an Asker Certified™ answer! navaru verified that this solution worked for them--which means it will likely work for you, too. Click to view the solution free for 30-days now.

About this solution

Zones: Signal Processing, Programming Languages, Processor Programming for Specific Platforms
Tags: keypad, pic, 4x4
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Solution Provided By: jaime_olivares
Participating Experts: 3
Solution Grade: B
 
[+][-]12/05/07 11:32 PM, ID: 20417873Author Comment

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[+][-]12/06/07 08:37 AM, ID: 20420951Expert Comment

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