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How to program a keypad exactly like the mobile phone keypad using PIC?

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shanishp

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May i know how could i programming a keypad extractly like the mobile phone keypad using PIC? For instance, when we first press the 2 button, it is an 'a', second press is a 'b' den is 'c',finally is '2', then it repeat the routine. Same for other buttons. So, the 4x3 keypad can have output for 0-9 and a-z. Please kindly give me the code if anyone of you have it, or at least give me an idea how to program it. Thx in advance.

it will be helpful if the code is in c
 

Re: keyboard scanning

It is simple, you will have to bring this into your coding and keep three different routines for each, keep in coding when any key pressed a counter from 1-4 should be updated on each press and keep a very short time delay in between each two presses in such a way that you coding should check that if any key is pressed the next key (if presses in next short time) then it should update the counter 1-3 but if next key is not pressed in that short time it means that the user this want a letter (a-z or 0-9) then the program should jump on the selected rountine.

Here you have to control key bouncing too. I hope I could explain that you want.

regards
 
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