In most keypads, pressing a key closes a contact that bridges two lines in an xy matrix. If you use a microcontroller to detect a key closure, checking the states of (x+y) lines requires an equal ...

A PIC16877 microcontroller is used to connect in particular to a 4X5 keypad which can also be connected with logic and analogue circuits. A PIC16877 microcontroller is used to connect in particular to ...