PC87393F datasheet(76/148 Pages) NSC

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3.0 General-Purpose Input/Output (GPIO) Port (Continued)

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3.4.1

GPIO Pin Configuration (GPCFG) Register

This is a group of eight identical configuration registers, each of which is associated with one GPIO pin. The entire set is

mapped to the PnP configuration space. The mapping scheme is based on the GPSEL register that functions as an index

register, and the specific GPCFG register that reflects the configuration of the currently selected pin. For details on the

GPSEL register, refer to the

Device Architecture and Configuration chapter.

Bits 4-6 are applicable only for the enhanced GPIO port with event detection support. In the basic port, these bits are re-

served, return 0 on read and have no effect on port functionality.

Location:

Device specific

Type:

R/W (bit 3 is set only)

Bit

76543210

Name

Reserved

Event

Debounce

Enable

Event

Polarity

Event Type

Lock

Pull-Up

Control

Output

Type

Output

Enable

Reset

01000100

Bit

Description

Reserved

Event Debounce Enable

0: Disabled

1: Enabled (default)

Event Polarity. This bit deﬁnes the polarity of the signal that causes a detection of an event from the

corresponding GPIO pin (falling/low or rising/high).

0: Falling edge or low level input (default)

1: Rising edge or high level input

Event Type. This bit deﬁnes the signal type that causes detection of an event from the corresponding GPIO pin.

0: Edge input (default)

1: Level input

Lock. This bit locks the corresponding GPIO pin. Once this bit is set to 1 by software, it can only be cleared to

0 by system reset or power-off. Pin multiplexing is functional until the Multiplexing Lock bit is 1. (Refer to the

Device Architecture and Configuration chapter.)

0: No effect (default)

1: Direction, output type, pull-up and output value locked

Pull-Up Control. This bit is used to enable/disable the internal pull-up capability of the corresponding GPIO pin.

It supports open-drain output signals with internal pull-ups and TTL input signals

0: Disabled

1: Enabled (default)

Output Type. This bit controls the output buffer type (open-drain or push-pull) of the corresponding GPIO pin.

0: Open-drain (default)

1: Push-pull

Output Enable. This bit indicates the GPIO pin output state. It has no effect on input.

0: TRI-STATE (default)

1: Output enabled

PC87393F Datasheet(PDF) 76 Page - National Semiconductor (TI)

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