AN1043 Просмотр технического описания (PDF) - Microchip Technology

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AN1043

Unique Features of the MCP23X08/17 GPIO Expanders

Microchip Technology 

AN1043

FIGURE 3:

INTERRUPT-ON-PIN-CHANGE EXAMPLE

GP3

Change cause interrupt.

Port state captured in

INTCAP

No affect on INT pin or

INTCAP

Change cause interrupt.

Port state captured in

INTCAP

Interrupt cleared and

INT

re-enabled

SPI

Read INTCAP or GPIO

Given:

- GP3 configured to “interrupt-on-pin-change”

- INT pin configured for “active low”

Read INTCAP or GPIO

FIGURE 4:

INTERRUPT-ON-CHANGE-FROM-DEFVAL EXAMPLE

GPINTEN – GPIO Interrupt-on-Change Enable Register

GPINT7 GPINT6 GPINT5 GPINT4 GPINT3 GPINT2 GPINT1 GPINT0

X

X

X

X

1

X

X

X

INTCON – Interrupt Control Register

IOC7 IOC6 IOC5 IOC4

X

X

X

X

IOC3

1

IOC2

X

IOC1

X

IOC0

X

DEFVAL – Default Value Register

DEF7 DEF6 DEF5 DEF4

X

X

X

X

DEF3

0

DEF2

X

DEF1

X

DEF0

X

GP3

INT

Change cause interrupt.

Port state captured in

INTCAP

No affect on INT

pin or INTCAP

Interrupt will occur if GP3 logic level = 1

INT remains

because GP3 = 1

(opposite of DEF3)

GP3 = DEF3

INT deactivates

after SPI read

SPI

Read INTCAP or GPIO

Read INTCAP or GPIO

DS01043A-page 4

© 2006 Microchip Technology Inc.

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