WM8991 datasheet(83/174 Pages) WOLFSON

83 / 174 page

Pre-Production

WM8991

PP, May 2008, Rev 3.1

GPIO CONTROL REGISTERS

Table 45 shows how the dual-function GPIO pins are configured to operate in their different modes.

Note that the order of precedence described earlier applies.

and GPIO functions. Register field ALRCGPIO1 enables the GPIO functionality on GPIO1. Register

field MCLK_SRC enables the GPIO functionality on GPIO2. Register field ALRCGPIO6 enables the

inverted ADCLRC output on GPIO6. Register bit AIF_TRIS, when set, takes precedence over

AIF_SEL, ALRCGPIO1, MCLK_SRC and ALRCBGPIO6 and tri-states all GPIO pins.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R7 (07h)

MCLK_SRC

MCLK Source Select

0 = MCLK pin

1 = GPIO2/MCLK2 pin

R8 (08h)

AIF_SEL

Audio Interface Select

0 = Audio interface 1

1 = Audio interface 2 (GPIO3/BCLK2,

GPIO4/DACLRC2, GPIO5/DACDAT2)

ALRCGPIO1

ADCLRC/GPIO1 Pin Function Select

0 = ADCLRC

1 = GPIO1 (ADCLRC connected to

DACLRC internally)

ALRCBGPIO6

GPIO6/ADCLRCB Pin Function Select

0 = GPIO6

1 = Inverted ADCLRC clock output

R9 (09h)

AIF_TRIS

Audio Interface and GPIO Tristate

0 = Audio interface and GPIO pins

operate normally

1 = Tristate all audio interface and GPIO

pins

Table 45 GPIO and GPI Pin Function Select

The GPIO pins are also controlled by the register fields described in Table 46. Note the order of

precedence described earlier applies.

Pull-up and pull-down resistors may be enabled on any of GPIO1 to GPIO6. If enabled, these

settings take precedence over all other GPIO selections for that pin. Note that, by default, the pull-

down resistors on GPIO2, GPIO3, GPIO4, GPIO5 and GPIO6 are enabled.

When the GPIO pins are used as inputs, de-bounce and interrupt masking may be controlled on all

GPIO pins (including GPI7 and GPI8) using GPIOn_DEB_ENA and GPIOn_IRQ_ENA bits as shown

in Table 47.

For each of GPIO1 to GPIO6, the register field GPIOn_SEL is used to select the pin functions of the

individual GPIO pins as shown in Table 47. Note that this control has the lowest precedence and is

only effective when GPIOn_PU, GPIOn_PD, AIF_TRIS, AIFSEL, MCLK_SRC, ALRCGPIO1 and

ALRCBGPIO6 are set to allow GPIO functionality on that GPIO pin.

WM8991 Datasheet(PDF) 83 Page - Wolfson Microelectronics plc

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