Create your own matrix keypad

Creating Matrix Keypad
To construct own matrix keypad is very easy. Only you have to know logic of Matrix and keypad. Normal switches are being used for one application. For more, what is necessary? We use keypad applications for micro controller for more useful projects. Keypad is necessary to use our projects for more functions and reliable applications.

MATRIX
we generally remember the showing matrix as [ 3 2 1 ; 2 2 2; 2 2 1] as 3x3 matrix it has 9 elements. It has 3 rows and 3 columns. This basic informations are needed for constructing matrix keypad. 

First of all, you have to know how many buttons do you need? After that we can choose mxn matrix keypad. Then we will construct it. For example I have an project that needs 12 buttons. First question is answered. Next is, which matrix keypad is needed? 3x3, 4x3, 4x4 etc. For 12 buttons, 4x3 (=12) is enough (exactly). And final part is constructing our matrix keypad.

CONSTRUCTION KEYPAD
As you see in matrix, you place elements in an coordinate system. for each element you have to know row and column number. So it gives us an idea to categorise cables as rows and columns. Each switch has 2 pins. One for input cable to the switch, other is output cable from switch. so we make S/C to input pins as one row( or column) on same line. And similarly, we solder the column pins as one column (or row). And we have matrix keypad. 

Attention: Don't forget to check all switches and components are stable before soldering.

Example for 2x2 matrix keypad. Attention on switch's pins. They are regrouped for rows or columns.

R1 and R2 represent rows and C1 and C2 represent columns. As this example you can make mxn matrix keypad. Only you have to regroup columns and rows pins.

If you make your own matrix keypad, you'll have chance to make it as you want. (buttons, dimensions etc. What ever you want. Enjoy it.

TESTING KEYPAD
you bought a new keypad but you don't know which cable is row or column. To learn that you have to check each button from cables. First, use DMM(digital multi meter as diode test) check cable 1 and 2 while use pushing button 1, later 1 and 3 etc. you can find all rows and columns with this way if you have no chance to check soldering way or circuit diagram.

Also you can watch my video about it in http://www.youtube.com/hasansnk . (Subtitle will be added)

My keypad's cost is only near $1

In pictures above, I make my own 4x3 keypad which has 6x6x4.3 (mm) buttons and its dimensions 4.5x3 (cm). I used one core cables. Ethernet cable has 8 small cables inside which is ideal to use for PCB applications. If you buy 1 m ethernet cable (Cat5), you will have 8x1 m one-core cables.

COMPONENTS:
12 pcs 6x6x4.3 mm push button switches, 20cm length one-core cable, solder and soldering iron, 4.5x3 cm PCB, stackable header which is 8 pin female header.