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Topic: membrane 1x4 keypad (Read 1 time) previous topic - next topic

bobrosco

I just want to check something because for some reason it wont work like i think it should.
I have this  keypad
It has 5 connections. And if im right 1 should be 5v from the arduino and all the others should be outputting 5v when pressed. And according to the tutorials i have read you should connect it to ground trough a resistor and to the arduino. And thats exactly what i did, but for some reason i dont get any response in my arduino.

So the question is did i hook it up right like that? Or is there a different way to use these?

groundFungus

I would connect the common to ground and each digit to a digital input with the internal pull ups enabled.  The key that is pushed will go LOW.   Unpushed keys will read HIGH.  This is the most common and accepted way to wire switches.

DrAzzy

I would connect the common to ground and each digit to a digital input with the internal pull ups enabled.  The key that is pushed will go LOW.   Unpushed keys will read HIGH.  This is the most common and accepted way to wire switches.
Yup - this is absolutely the way to go.

Without seeing how you actually wired it, I can't tell where you went wrong. My guess is you did the external pulldowns wrong - but if you wire it as advised above, you don't need to use external resistors.
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bobrosco

thank you. I got that working now.

JoeN

When working with any circuit like this, use the continuity tester feature on your multimeter and make sure you know the common and what is going on.  Pick pairs of wires and start pressing buttons.  I like buzzing out unknown combinations like that.  You can do the reverse with LED matrices by providing current and ground, one of them through a 470 ohm resistor or so, and simply testing out the combinations.  You don't need no stinkin' datasheet for these types of devices, it's a very easy puzzle to solve.
I will never ask you to do anything that I wouldn't do myself.

Paul__B

When working with any circuit like this, use the continuity tester feature on your multimeter and make sure you know the common and what is going on.
Mind you if you take a look at the picture ("View Image"), it is immediately obvious which is the common in this case.

JoeN

#6
Aug 13, 2015, 03:08 am Last Edit: Aug 13, 2015, 03:09 am by JoeN
Mind you if you take a look at the picture ("View Image"), it is immediately obvious which is the common in this case.
Good point.  And yet I still believe I correctly inferred the original poster (a "newbie") could use some general advice in addition to the specific advice given.
I will never ask you to do anything that I wouldn't do myself.

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