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Radar
09-23-2007, 05:39 PM
:pHi Guys.

:roll:Can someone tell me what this means?


{You will also get 32 Digital Switches using an X/Y matrix
arrangement.}


It's from this board http://www.lbodnar.dsl.pipex.com/joystick/index.html

JBaymore
09-23-2007, 07:15 PM
Radar,

Matrix type connections allow a circuit to get away with fewer components. Any specific location on the matrix is a combination of X and Y coordinates on a grid.

Q R
A-------|--------|---------------------
| |
B-------|--------|--------------------
| |
C-------|--------|---------------------
| |
D-------|--------|---------------------

(Sorry I can't get the lines to line up correctly... but the font is not allowing it. Think of the Q and R as being located OVER the lines running vertically.)

Now, I can connect one leg wiring of a key to the location BR, and have that location when connected to Ground send the keypress "1". I can then connect a wire to location BQ and have it send the keypress "2".

You'll notice that the circuit for the B line already has TWO possible keys that it can send. These kinds of circuits are prone to what is called ""ghosting"....sending keypresses that aren't intended.

A better approach is to have discrete inputs for such work.... but it is more expensive because of the added complexity of doing so.

best,

....................john

andarlite
09-23-2007, 07:22 PM
This device has 6 X inputs and 6 Y inputs. That means you can connect 36 switches to it..... on the web page you provided take a look at the diagram on the right which shows the switch matrix and how the switches are connected together. Because 4 of the switches are reserve for the Hat switch, that leaves you a possible 32 switches.

Regards,
Henry

Westozy
09-23-2007, 07:23 PM
Stay away from matrix boards - old technology, as John says - ghosting issues etc.

Gwyn

Bob Reed
09-23-2007, 07:31 PM
Matrix boards are not that bad.. Just have to use a diode to keep from getting the ghosting....:rolleyes:

JBaymore
09-23-2007, 07:49 PM
By the time you bother with all the time to solder in all the diodes plus the cost of solder and diodes...... why not just spend a couple of bucks more for discrete inputs? My $0.02.

best,

..................john

Radar
09-23-2007, 08:07 PM
By the time you bother with all the time to solder in all the diodes plus the cost of solder and diodes...... why not just spend a couple of bucks more for discrete inputs? My $0.02.

best,

..................john


Discrete inputs? What are they, and can I still use this board with discrete inputs?

THKS JB

Bob Reed
09-23-2007, 08:11 PM
What board do you have?

Radar
09-23-2007, 09:07 PM
http://www.lbodnar.dsl.pipex.com/joystick/index.html
What board do you have?

Michael Carter
09-23-2007, 09:11 PM
Descreet inputs on a board are also called direct inputs. A matrix is not used.

The inputs on a matrix board can in most cases also be used in a direct mode, but will cut down on your inputs dramatically.

If you have 36 imputs for use in matrix mode, I think the inputs get cut down to 12, but my math may be faulty.

I will no longer use a matrixed input board as I don't like dealing with the diodes.

JBaymore
09-23-2007, 09:11 PM
Radar,

No... if you HAVE that board... it is a matrix input setup. That is what ya' got. Boeing above beat me to the explanation.

I thought you were looking at BUYING that board....and was sort of steeing you away from it if possible.

best,

,...................john