Computer Keyboard Matrix Circuit

Thus allowing it to determine which key is pressed.

Computer keyboard matrix circuit. The key matrix is a grid of circuits underneath the keys. The trick is to use a keyboard matrix e g. When you press any particular key it completes this circuit thus enabling the processor to determine the location of the key that was pressed. A keyboard matrix circuit is a design used in most electronic musical keyboards and computer keyboards in which the key switches are connected by a grid of wires similar to a diode matrix for example 16 wires arranged in 8 rows and 8 columns can connect 64 keys sufficient for a full five octaves of range 61 notes.

The keyboard is a typical scanning matrix of keys so i suspected a problem with one of the column wires. You can read more about how that. A keyboard is a lot like a miniature computer. Of course this isn t real od but it solves the current loop problem in a keyboard matrix.

There is a tiny flexible cap at every key position. This way the pin set to 1 will never source current and this nearly makes it an od pin. More on that to follow. It has its own processor and circuitry that carries information to and from that processor.

A keyboard matrix is a great way to add buttons without using up all of your i o pins. By scanning these crossings a keyboard controller can determine which. Keyboard matrix circuits contain a scanner that s constantly scanner the grid. The keyboard switch matrix is wired to its inputs and it processes the incoming keystrokes and sends the results down a serial cable the keyboard cord to a receiver in the main computer box.

A large part of this circuitry makes up the key matrix. When we lift off the matrix take great care. It also controls the illumination of the caps lock num lock and scroll lock lights. My latest project has 64 buttons.

Look carefully for any discoloration that would possibly indicate the problem area. Dave dribin has an excellent description about how these keyboards work. 5 rows x 15 columns and quickly cycle through each row column allowing you to use 2n pins only for a n x n matrix. The key matrix is a collection of circuits under the keyboard which is broken at a specific point under every key which results in making the circuit incomplete.

Go back to the first matrix circuit but take into account the green overlay this time to see how this solution looks. In this keyboard matrix tutorial i showed how a 9 button matrix works. These are the actual matrix of the keyboard. In all keyboards except for capacitive models.

This same code and circuit are what i m using for a new project.