Datasheet

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MCP23018/MCP23S18

1.5 GPIO Port

The GPIO module is a general purpose 16-bit wide

bidirectional port which is functionally split into two (2)

8-bit wide ports.

The outputs are open-drain.

The GPIO module contains the data ports (GPIOn),

internal pull up resistors and the Output Latches

(OLATn).

The pull up resistors are individually configured and

can be enabled when the pin is cofigured as an input or

output.

Reading the GPIOn register reads the value on the

port. Reading the OLATn register only reads the

latches, not the actual value on the port.

Writing to the GPIOn register actually causes a write to

the latches (OLATn). Writing to the OLATn register

forces the associated output drivers to drive to the level

in OLATn. Pins configured as inputs turn off the associ-

ated output driver and put it in high-impedance.

TABLE 1-2: SUMMARY OF REGISTERS ASSOCIATED WITH THE GPIO PORTS (BANK = 1)

TABLE 1-3: SUMMARY OF REGISTERS ASSOCIATED WITH THE GPIO PORTS (BANK = 0)

Name

Address

(hex)

bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

POR/RST

value

IODIRA 00 IO7 IO6 IO5 IO4 IO3 IO2 IO1 IO0 1111 1111

IPOLA 01 IP7 IP6 IP5 IP4 IP3 IP2 IP1 IP0 0000 0000

GPINTENA 02 GPINT7 GPINT6 GPINT5 GPINT4 GPINT3 GPINT2 GPINT1 GPINT0 0000 0000

GPPUA 06 PU7 PU6 PU5 PU4 PU3 PU2 PU1 PU0 0000 0000

GPIOA 09 GP7 GP6 GP5 GP4 GP3 GP2 GP1 GP0 0000 0000

OLATA 0A OL7 OL6 OL5 OL4 OL3 OL2 OL1 OL0 0000 0000

IODIRB 10 IO7 IO6 IO5 IO4 IO3 IO2 IO1 IO0 1111 1111

IPOLB 11 IP7 IP6 IP5 IP4 IP3 IP2 IP1 IP0 0000 0000

GPINTENB 12 GPINT7 GPINT6 GPINT5 GPINT4 GPINT3 GPINT2 GPINT1 GPINT0 0000 0000

GPPUB 16 PU7 PU6 PU5 PU4 PU3 PU2 PU1 PU0 0000 0000

GPIOB 19 GP7 GP6 GP5 GP4 GP3 GP2 GP1 GP0 0000 0000

OLATB 1A OL7 OL6 OL5 OL4 OL3 OL2 OL1 OL0 0000 0000

Name

Address

(hex)

bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

POR/RST

value

IODIRA 00 IO7 IO6 IO5 IO4 IO3 IO2 IO1 IO0 1111 1111

IODIRB 01 IO7 IO6 IO5 IO4 IO3 IO2 IO1 IO0 1111 1111

IPOLA 02 IP7 IP6 IP5 IP4 IP3 IP2 IP1 IP0 0000 0000

IPOLB 03 IP7 IP6 IP5 IP4 IP3 IP2 IP1 IP0 0000 0000

GPINTENA 04 GPINT7 GPINT6 GPINT5 GPINT4 GPINT3 GPINT2 GPINT1 GPINT0 0000 0000

GPINTENB 05 GPINT7 GPINT6 GPINT5 GPINT4 GPINT3 GPINT2 GPINT1 GPINT0 0000 0000

GPPUA 0C PU7 PU6 PU5 PU4 PU3 PU2 PU1 PU0 0000 0000

GPPUB 0D PU7 PU6 PU5 PU4 PU3 PU2 PU1 PU0 0000 0000

GPIOA 12 GP7 GP6 GP5 GP4 GP3 GP2 GP1 GP0 0000 0000

GPIOB 13 GP7 GP6 GP5 GP4 GP3 GP2 GP1 GP0 0000 0000

OLATA 14 OL7 OL6 OL5 OL4 OL3 OL2 OL1 OL0 0000 0000

OLATB 15 OL7 OL6 OL5 OL4 OL3 OL2 OL1 OL0 0000 0000