ST AN2466 APPLICATION NOTE

AN2466

Application note

STMPE801 - Hardware Interface guide

Introduction

STMPE801 is an eight-bit port expander that can be interfaced to the main digital ASIC or processor via the two-line bidirectional I2C bus. The digital engines in mobile multimedia platforms usually come with a limited number of I/Os. The port expander ICs can be used to increase the number of I/Os or control signals in such applications.

STMPE801 can be used in advanced digital platforms such as:

●Portable media players

●Game consoles

●Mobile phones

●Smart phones etc.

This application note explains the setup and hardware interfacing of the device to the main processor.

March 2007

Rev 1

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Contents	AN2466

Contents

1	STMPE801 Device features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		3
2	Pin description of STMPE801 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		4
	2.1	Power Supply - VCC and VIO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	5
	2.2	I2C Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	5
		2.2.1 I2C General call . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	7
	2.3	Reset pin (RESET_N) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	7
	2.4	Interrupt pin (INT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	8
	2.5	GPIO Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	8

2.5.1 Configuring GPIO registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.5.2 GPIO Level shifting feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.5.3 GPIO-Hot Key feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.6 Minimum pulse width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.7 Power saving mode of operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.8 Power-Up sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

3	Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	12
4	Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	12

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AN2466	STMPE801 Device features

1 STMPE801 Device features

Figure 1. Concept of GPIO Port Expander

VCC

VIO

CLOCK

GPIO 0

Hotkey

DATA

GPIO 1

Chip Enable

GPIO 2

Temperature Sensor

Processor

ADDRESS

GPIO 3

Control Signal/Ext.Interrupt

STMPE801

INT

GPIO 4

GPIO 5

GPIO 6

RST_N

GPIO 7

LED BANK

GND

–Low CPU utilization (Interrupts available and so no Polling!)

–Configurable Hotkey Detection on each GPIO

–Flexibility in configuration of each of the eight GPIOs

–Simpler communication with CPU (just two I2C lines)

–Low power consumption with ultra low standby current (< 1 A)

–IO and core voltages from 1.65 V up to 3.6 V

–Interrupt output (open drain) pin

–No external clock input required

–Small package QFN16 - 16 pins 1.8 mm x 2.6 mm, making it optimal for use in portable application like mobile phones with critical space constraints.

The STMPE801 offers great flexibility as each I/O can be independently configured as input or output. The eight GPIOs can be connected externally to different modules like LEDs, temperature sensors, chip selects for other devices, or as interrupt inputs from other devices.

This device has been designed with very low quiescent current in standby mode and includes a Hot Key detection for each I/O to optimize the power consumption of the IC.

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Pin description of STMPE801	AN2466

Figure 2. Block diagram of STMPE801

		GPIO Controller	GPIO
			0-7	GPIO 0-7
				VIO
	ADDRESS			INT
	CLOCK	2
		I C
			POR
	DATA	Interface		RESET_N

VCC GND

2 Pin description of STMPE801

The table below gives a list of all the pins on STMPE801.

	Table 1.	STMPE801 Pin description
	Pin	Name	Type	Description
	1	INT	O	Interrupt output (open drain)
	2	Reset_N	I	External reset input, active LOW
	3	CLOCK	A	I2C Serial clock line
	4	ADDRESS	I	Digital Input for I2C slave address (either High or Low)
	5	DATA	A	I2C Serial data line
	6	VCC	-	Supply voltage for I2C block
	7	VIO	-	Supply voltage for GPIO controller (Note: VIO must always
				be ≥ VCC)
	8	GND	-	GND
	9	GPIO_0	IO	GPIO
	10	GPIO_1	IO	GPIO
	11	GPIO_2	IO	GPIO
	12	GPIO_3	IO	GPIO
	13	GPIO_4	IO	GPIO
	14	GPIO_5	IO	GPIO

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