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Keypad Matrix - help with circuitry needed

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H

howie

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Keypad Matrix

Hello to all..

Can someone give me an idea on how to construct a circuit given the attached 5x3 keypad matrix below. I need to minimize GPIOs into "4" from the given 8 GPIOs?

Regards to all.
 

Re: Keypad Matrix

Hi

You will not be able to control 15 switches using 4 I/O lines (direct digital)!

There are several ways to solve the problem:

1) easy but costly to use keypad control IC like the MAX7360

2) Use an ADC and resistor network as suggested else ware by smd_lover.

3)use low cost shift register IC like the 74HC165 and its counter part

All the best

B0bi
 

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