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4 by 4 Keypad

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brent4669

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Hi

I am having trouble designing a 4 by 4 key pad circuit with an 8 bit output. I am using a straight ring counter as the shift register and either a 74LS273 or 74C922 latch for the outputs. I am having trouble connecting my logic gates (andor) to the columns for the key press detect. Any help would be grateful even just a point in the right direction.

Thanks
 
I put together a 4X4 keypad encoder not to long ago. Here is how I did it...
 

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Last edited:
Manners are nice, have you heard of them. In case you didnt read the post properly I didnt mention anything about Pic/Microcontrollers
 
Mike used a uC, the OP doesnt want to use one and is therefore rudely saying that Mike has no manners because he showed the OP a diagram using a uC
 
How would you interpret the data without one?

With the solution I gave you could have either serial or parallel output.
 
Last edited:
Mike used a uC, the OP doesnt want to use one and is therefore rudely saying that Mike has no manners because he showed the OP a diagram using a uC


It's a 4X4 matrix decoder chip. There is no uC involved with that project. You could feed the serial data into a uC or have parallel output.
 
brent4669 is clearly the one lacking in manners.

Where did you get that nice keypad, Mike?
 
THANK YOU! I've been looking for one EXACTLY like that!
 
Used to be, those keypads were about $5.00, until they realized everyone with a micro controller would be buying one, or two.
 
$12 is a GREAT deal as far as I'm concerned. Digikey's least expensive 4x4 keypad is $13.66 and NONE of them have the right legend - alphanumerics for hex entry, arrow keys for the cursor (I use multline LCDs with menus), clear, entry, and even a damn "Help" button! (I include "help" files on my test fixtures so the techs won't bug me so much)

Mike, this is BEAUTIFUL!
 
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