In this text is explained how to create a matrix keyboard. A matrix keyboard is a keyboard with a X and Y axis. The combination of X and Y is a position and that position has a variable letter or number.

For example a phone has the same keyboard.

In the following figure is shown how a matrix keyboard works. The scanner first scans the columns and then the rows.

Scheme

A state machine scans the colums, if no key pressed with 0.01 sec.

Simulation

The next figure is the Schematic in Realizer simulator. There is shown that the user pressed key 11. As you can see Key 11 is on the 3rd column and on the 4th row. This schematic is made to give keys a coordinate so they can be easily found.

DOWNLOAD

keymap.zip

Prepared for devices: ST72331N4 PIC16F785 other devices possible by reconnecting I/O pins.