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#### brent4669

##### New Member
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

#### blueroomelectronics

##### Well-Known Member
4x4 is only 4 bits, post your schematic.

#### Mike_2545

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

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#### brent4669

##### New Member
Thanks for the suggestion Mike

#### brent4669

##### New Member
Manners are nice, have you heard of them. In case you didnt read the post properly I didnt mention anything about Pic/Microcontrollers

#### Mike_2545

##### Super Moderator
Manners are nice, have you heard of them. In case you didnt read the post properly I didnt mention anything about Pic/Microcontrollers

#### ParkingLotLust

##### Member
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

#### Mike_2545

##### Super Moderator
How would you interpret the data without one?

With the solution I gave you could have either serial or parallel output.

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#### Mike_2545

##### Super Moderator
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.

#### duffy

##### Well-Known Member
brent4669 is clearly the one lacking in manners.

Where did you get that nice keypad, Mike?

#### duffy

##### Well-Known Member
THANK YOU! I've been looking for one EXACTLY like that!

#### Mike_2545

Used to be, those keypads were about $5.00, until they realized everyone with a micro controller would be buying one, or two. #### duffy ##### Well-Known Member$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!

#### blueroomelectronics

##### Well-Known Member
brent4669 you still haven't posted your schematic.

#### Mike_2545

##### Super Moderator
brent4669 you still haven't posted your schematic.
I think he tucked his tail and ran

#### jakeselectronics

##### Member
Yep... 6 months later and he's still gone...

For anyone whos is interested I have designed a PCB to use as a keypad interface. and it outputs 8 bits.

Now i know 4x4 matrix is only 4 bits.. but if you press 2 buttons succesively you will get 8 bits of data from my PCB (It uses a 74HC164).

Jake's Electronics - Kits, Tutorials, Projects and More.

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