Home     Forum     Projects     Experiments     Circuits     Theory     BLOG     PIC Tutorials     Time for Science

### Author Topic: help with - KEYPAD,12-BUTTON NUMERIC,BLACK 10-PIN 2 WIRES(10)  (Read 2889 times)

0 Members and 1 Guest are viewing this topic.

• Guest
##### help with - KEYPAD,12-BUTTON NUMERIC,BLACK 10-PIN 2 WIRES(10)
« on: March 17, 2012, 04:09:01 AM »
Looking for help in configuring a breadboard that utilizies the following keypad:

Need a unique way to determine which key was pressed...
Having issue w/ ghosting... i.e., - if black, white, purple input/wires are hot ("+") - blue wire output will be hot ("+") - if keys 1, 4, 7 are pressed...

KEYPAD,12-BUTTON NUMERIC,BLACK 10-PIN 2 WIRES(10)FOR CONNECTN
Manufacturer   JAMECO VALUEPRO
Manufacturer no. 10-PINKP-2

-Matrix Layout-
{Blk –Bwn Wire}
[1  2  3]
[4  5  6]
[7  8  9]
[*  0  #]

[Wire Layout]
Brown (Bwn) -------
Red ------------------
Orange --------------
Yellow --------------
Green ----------------
Blue  ----------------
Purple ---------------
Gray -----------------
White ----------------
Black (Blk) ---------

-Output Combinations-

1 = Black,   Blue
2 = Black,   Green
3 = Black,   Yellow
4 = White,   Blue
5 = White,   Green
6 = White,   Yellow
7 = Purple,   Blue
8 = Purple,   Green
9 = Gray,   Yellow
* = Red,   Orange
0 = Purple,   Yellow
# = Red,   Brown

Thanks in advance for any help in configuring a breadboard for a solution to this issue...

thx

#### kam

• Hero Member
• Posts: 1849
##### Re: help with - KEYPAD,12-BUTTON NUMERIC,BLACK 10-PIN 2 WIRES(10)
« Reply #1 on: March 17, 2012, 09:31:39 AM »
I suppose you will add a microcontroller on that breadboard, right? Otherwise it will be a real pain to make it on a breadboard. with a micro you might find some pre-made routines (usually exist for arduino staff).

if microcontrollers is not your best, you will need a 4017 and some AND gates. Here is how it works. The 4017 outputs are connected to the horizontal matrix wires (in your case black white purple grey red).  So as it scrolls, it gives HIGH to one row every time.  The same output gives also high to one input of 3 AND gates. The other 3 inputs of these gates are connected to the vertical rows of your matrix, in your case blue green yellow (the orange needs a 4th AND gate).  This configuration requires 4x3 AND gates (12 total). So, if no button is pressed, only the first input of all AND gates is high, thus getting NO output. But if you press one button then there will be one AND gate which will have both inputs HIGH and this gate will be high
Keep in mind  that the HIGH on this AND output will last only as long as the clock duration lasts. (i forgot to tell you that there is a clock connected to the clock input of the 4017). That is because the 4017 scrolls around the 4 rows so the output is high only as long as the key is presses AND the 4017 output points to this row. You may wanna add an one-shot circuit to the outputs of the AND gates to get a constant output...