WM8904ECSSLASHR datasheet(115/188 Pages) WOLFSON

115 / 188 page

Pre-Production

WM8904

PP, Rev 3.3, September 2012

115

GENERAL PURPOSE INPUT/OUTPUT (GPIO)

The WM8904 provides four multi-function pins which can be configured to provide a number of

different functions. These are digital input/output pins on the DBVDD power domain. The GPIO pins

are:



IRQ/GPIO1



GPIO2



GPIO3



BCLK/GPIO4

Each general purpose I/O pin can be configured to be a GPIO input or configured as one of a number

of output functions. Signal de-bouncing can be selected on GPIO input pins for use with jack/button

detect applications. Table 74 lists the functions that are available on each of the GPIO pins.

GPIO Pin Function

GPIO PINS

IRQ / GPIO1

GPIO2

GPIO3

BCLK / GPIO4

GPIO input

(including jack/button detect)

Yes

GPIO output

Yes

BCLK

Yes

Interrupt (IRQ)

Yes

MICBIAS current detect

Yes

MICBIAS short-circuit detect

Yes

Digital microphone interface

(DMIC clock output)

Yes

FLL Lock output

Yes

FLL Clock output

Yes

Table 74 GPIO Functions Available

IRQ/GPIO1

The IRQ/GPIO1 pin is configured using the register bits described in Table 75. By default, this pin is

IRQ output with pull-down resistor enabled.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R121 (79h)

GPIO

Control 1

GPIO1_PU

GPIO1 pull-up resistor enable

0 = pull-up disabled

1 = pull-up enabled

GPIO1_PD

GPIO1 pull-down resistor enable

0 = pull-down disabled

1 = pull-down enabled

3:0

GPIO1_SEL [3:0]

0100

GPIO1 Function Select

0000 = Input pin

0001 = Clock output

(f=SYSCLK/OPCLKDIV)

0010 = Logic '0'

0011 = Logic '1'

0100 = IRQ (default)

0101 = FLL Lock

0110 = Mic Detect

0111 = Mic Short

1000 = DMIC clock out

1001 = FLL Clock Output

1010 to 1111 = Reserved

Table 75 IRQ/GPIO1 Control

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