SX8674ICSTRT datasheet(41/64 Pages) SEMTECH

41 / 64 page

ADVANCED COMMUNICATIONS & SENSING

Rev 1 – 25

th July 2011

www.semtech.com

SX8674/SX8675/SX8676

Haptics Enabled Multitouch 4/5-Wire

Resistive Touchscreen Controller with Proximity Sensing

INTERRUPT (NIRQ)

8.1

Introduction

The purpose of the NIRQ pin is to indicate to the host (via a falling edge) when any of the events considered

being time-critical has occurred. Non time-critical events can be monitored via I2C by reading regularly the

relevant status bits.

8.2

Registers Overview

8.2.1

RegIrqMsk

This register allows the host to decide which interrupt sources he wants to monitor via the NIRQ signal. Please

note that a reset event will always trigger NIRQ falling edge whatever RegIrqMsk (Cf §10)

8.2.2

RegIrqSrc

This register indicates to the host which of the interrupt sources triggered the NIRQ signal. More than one bit

can be set if several events occurred before host reads the register.

If bit 3 is OFF, reading the register will clear it together with releasing NIRQ signal. Else, if bit 3 is ON and we are

in MAN or PENTRG mode, both register and NIRQ will be cleared only once all channel data have been read. All

ADC related operations (touch conversion, proximity conversion, pen detection) are stopped as long as all

channel data have not been read.

Bits which RegIrqMsk corresponding bits are set to 0 (ie source not monitored) will always read 0 even if the

event actually occurred.

8.2.3

RegStat

This register regroups all status information of the chip and is used by all interrupt sources to detect the relevant

events. For each bit, if the relevant block is ON its value is constantly updated, else it is set to 0. This register

update is completely independent from RegIrqMsk.

8.3

Host Procedure

Configure the different blocks parameters(TS, Proximity, etc)

Program RegIrqMsk to start monitoring what is considered to be “time-critical” events

Enable the blocks to start RegStat update and hence NIRQ process.

Each time NIRQ falling edge occurs, read RegIrqSrc to know which “time-critical” event occurred (+ read

channel data if relevant)

In addition, RegStat can be read anytime to get the whole picture including also what is considered to be

“non time-critical” information.

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