MCP23008-ESLASHSS datasheet(13/40 Pages) MICROCHIP

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DS21919B-page 13

MCP23008/MCP23S08

1.6.6

CONFIGURATION (IOCON)

The

IOCON

contains

several

bits

for

configuring the device:

• The Sequential Operation (SEQOP) controls the

incrementing function of the address pointer. If

the address pointer is disabled, the address

pointer does not automatically increment after

each byte is clocked during a serial transfer. This

feature is useful when it is desired to continuously

poll (read) or modify (write) a register.

• The Slew Rate (DISSLW) bit controls the slew

rate function on the SDA pin. If enabled, the SDA

slew rate will be controlled when driving from a

high to a low.

• The Hardware Address Enable (HAEN) control bit

enables/disables the hardware address pins (A2,

A1) on the MCP23S08. This bit is not used on the

MCP23008. The address pins are always enabled

on the MCP23008.

• The Open-Drain (ODR) control bit

enables/disables the INT pin for open-drain

configuration.

• The Interrupt Polarity (INTPOL) control bit sets

the polarity of the INT pin. This bit is functional

only when the ODR bit is cleared, configuring the

INT pin as active push-pull.

IOCON – I/O EXPANDER CONFIGURATION REGISTER (ADDR 0x05)

U-0

R/W-0

U-0

—

SEQOP

DISSLW

HAEN

ODR

INTPOL

—

bit 7

bit 0

bit 7-6

Unimplemented: Read as ‘0’.

bit 5

SEQOP: Sequential Operation mode bit.

= Sequential operation disabled, address pointer does not increment.

= Sequential operation enabled, address pointer increments.

bit 4

DISSLW: Slew Rate control bit for SDA output.

= Slew rate disabled.

= Slew rate enabled.

bit 3

HAEN: Hardware Address Enable bit (MCP23S08 only).

Address pins are always enabled on MCP23008.

= Enables the MCP23S08 address pins.

= Disables the MCP23S08 address pins.

bit 2

ODR: This bit configures the INT pin as an open-drain output.

= Open-drain output (overrides the INTPOL bit).

= Active driver output (INTPOL bit sets the polarity).

bit 1

INTPOL: This bit sets the polarity of the INT output pin.

=Active-high.

=Active-low.

bit 0

Unimplemented: Read as ‘0’.

Legend:

R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

- n = Value at POR

‘1’ = Bit is set

‘0’ = Bit is cleared

x = Bit is unknown

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