This is a basic 12 button keypad that has been designed for easy user input and functionality.
The buttons are set up in a matrix format. This allows a microcontroller to ‘scan’ the 7 output pins to see which of the 12 buttons is being pressed.
Each of the keypad’s 12 buttons has been labeled 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, *, and # and has been formatted to into the same layout as a telephone keypad with each keypress resistance ranging between 10 and 150 Ohms.