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Hi.. How to scan this keyboard?

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sajeev

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Hi,
I got a keyboard like this.The board uses a pic16f628 and keyboard is connected to it as in figure.Whats the logic to scan all of the keys?

It is easy to scan 3x3 matrix keyboard.But what about the last row named k2 ?







Regards....
 

syrax

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i thinks the lasr row is unusable may be this is a standart keyboard , if you wanna scan 4x3 keypad you need 7 free pins

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blueroomelectronics

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It's an odd design for a matrix keyboard. Use a smaller matrix or a processor with more I/O

There is a way to decode a keypad with an A/D it's posted in Tips & Tricks on Microchips website.
 

sn_burki

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hi

in this desing 7pins are engaged, then what is the use??? you can design same keyboard in 4x3 matrix with 7pins.

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sztibi82

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You should rearrange the circuit by using a scanning method. For example in your case put diodes with anode towards pin 11, 12 and 13.
The cathodes will be connected to the matrix's columns.
The rows should be connected to 10,9,8 and 7.

By scanning with a successively, you can figure out which button was pressed.

This samples what I told you above, you can find in picbasic books.
In picbasic you have all functions already written, you have to use them only.
 

Code Warrior

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It is a matrix keyboard. Read Ayala for the same.
 

syrax

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i think it will be better if the pin who is conected to bi LED to conect to last row GND
and then it will be standart matrix k. 4x3 why some put LED? :)))) the keyboard is for typing not for blinking

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sajeev

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Its board of security system.I havent seen the working of the whole board.I think last row is a fake one, and the leds are for indicating correct password.

REGARDS...
 

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