Interface Ideas for a 25-Key Matrix Keypad

mhammer

Hi All,

Im planning a project and trying to research an interface for a 25-key Keypad.·· The Keypad is set up in a 5x5 Matrix.·· The interface is a 10 pin Connector.


I have looked at·the 74C922 Chip.·· This one supports a 4x4 Matrix and outputs 4 bits to the controller.·· I looked at the Nuts and Volts Column Number 97 for interface ideas.·· Does anyone know of an interface chip that can handle a 5x5 matrix?···Does anyone have any other ideas on how i can interface this keypad to a Stamp?·

JonnyMac

You could use a 74HC595/74HC165 combo with four pins to do the scan -- it would be a little slow, but would work and be very cheap. See StampWorks for a method of connecting the '595 and '165 together using just four I/O pins.

mhammer

Thanks Jonny i will look into this idea.··