LPC47M14X datasheet(112/205 Pages) SMSC

112 / 205 page

SMSC DS – LPC47M14X

Page 112

Rev. 03/19/2001

6.14.3

GPIO Control

Each GPIO port has an 8-bit control register that controls the behavior of the pin. These registers are defined in the

“Runtime Registers” section of this specification.

Each GPIO port may be configured as either an input or an output. If the pin is configured as an output, it can be

programmed as open-drain or push-pull. Inputs and outputs can be configured as non-inverting or inverting. Bit[0] of

each GPIO Configuration Register determines the port direction, bit[1] determines the signal polarity, and bit[7]

determines the output driver type select. The GPIO configuration register Output Type select bit[7] applies to GPIO

functions and the nSMI Alternate functions.

The Polarity Bit (bit 1) of the GPIO control registers control the GPIO pin when the pin is configured for the GPIO

function and when the pin is configured for the alternate function for all pins, with the exception of the DDRC function

on GP43, the analog game port pins (J1X, J1Y, J2X, J2Y) and the either edge triggered interrupts. When the

alternate function is selected for the analog joystick pins (GP14, GP15, GP16 and GP17), these pins become open

drain, non-inverted outputs.

The basic GPIO configuration options are summarized in Table 55.

Table 55 – GPIO Configuration Summary

SELECTED

FUNCTION

DIRECTION

BIT

POLARITY

BIT

DESCRIPTION

Pin is a non-inverted output.

Pin is an inverted output.

Pin is a non-inverted input.

GPIO

Pin is an inverted input.

6.14.4

GPIO Operation

FIGURE 8 – GPIO FUNCTION ILLUSTRATION

GPIO

Data Register

Bit-n

SD-bit

GPx_nIOR

GPIO

Configuration

(Polarity)

GPIO

Configuration

(Input/Output)

D-TYPE

Transparent

GPx_nIOW

LPC47M14X Datasheet(PDF) 112 Page - SMSC Corporation

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