3x4 Matrix Keypad

Punch in your secret key (or Jenny's number) into this numeric matrix keypad. This keypad has 12 buttons, arranged in a telephone-line 3x4 grid. The keys are connected into a matrix, so you only need 7 microcontroller pins (3-columns and 4-rows) to scan through the pad. Check the tutorials tab for links to an Arduino library and example code.