Microchip Technology Inc

AN1081

Title:
Interfacing a 4x4 Matrix Keypad with an 8-Bit GPIO Expander
Name:
AN1081
Date:
04/12/2007
Author:
Mike Curran
Description:
This application note discusses interfacing a 4x4 matrix keypad with MCP23X08 8-Bit GPIO Expander. This application note references the MCP23X08/17 GPIO Expander Keypad/LCD Demo Board (GPIODM-KPLCD). GPIO Expanders provide easy I/O expansion using standard serial interfaces such as I2C and SPI. They are especially useful in applications where pin count is limited on the microcontroller unit (MCU) or if remote inputs / outputs (I/O's) are needed. It is best to think of an 8-bit GPIO Expander like adding another 8-bit wide digital port to the MCU. This application note does not detail all of the features of the MCP23X08. Refer to the MCP23008/MCP23S08 Data Sheet, "8-Bit I/O Expander with Serial Interface" (DS21919) for more information.
Keywords:
GPIO, 4x4 Matrix, 8-Bit, keypad
 
 Application Notes & Source Code
 Last Updated
Size
 
  AN1081
  04/12/2007
  478KB
 Silicon Products
Last Updated
  MCP23008
  12/20/2004
  MCP23017
  05/07/2009
  MCP23S08
  01/25/2005
  MCP23S17
  06/24/2005