AN2421 Datasheet, PDF (1/6 Pages) STMicroelectronics – Using the STMPE801 as a keypad controller

AN2421
Application note
Using the STMPE801 as a keypad controller
Introduction
STMPE801 is an 8-bit general purpose port expander device in the STMicroelectronics Port
Expander Logic family. Its eight GPIOs (General Purpose Input Output) are connected to the
host system using a standard I2C connection.
This application note explains how to control an 8*8 (64-key) matrix keypad using the 8
internal GPIOs of a base-band processor and the 8 GPIOs of the STMPE801 port expander.
The simplified schematic is shown below.
Schematic for using STMPE801 as a keypad controller
Baseband
BB_GPIO
SDAT
SCLK
INT
STMPE801
801_GPIO
RST
November 2006
8*8
Keypad
Rev 1
1/6
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