WM8904ECSSLASHR datasheet(117/188 Pages) WOLFSON

117 / 188 page

Pre-Production

WM8904

PP, Rev 3.3, September 2012

117

BCLK/GPIO4

The BCLK/GPIO4 pin is configured using the register bits described in Table 78. By default, this pin

provides the BCLK function associated with the Digital Audio Interface. The BCLK function can

operate in slave mode (BCLK input) or in master mode (BCLK output), depending on the BCLK_DIR

It is possible to configure the BCLK/GPIO4 pin to provide various GPIO functions; in this case, the

BCLK function is provided using the MCLK pin. Note that the BCLK function is always in slave mode

(BCLK input) in this mode.

To select the GPIO4 functions, it is required to set BCLK_DIR = 0 (see Table 56) and to set

GPIO_BCLK_MODE_ENA = 1 (see Table 78 below). In this configuration, the MCLK input is used as

the bit-clock (BCLK) for the Digital Audio Interface.

When the BCLK/GPIO4 pin is configured as GPIO4, then the pin function is determined by the

GPIO_BCLK_SEL register field.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R124 (7Ch)

GPIO

Control 4

GPIO_BCLK_MODE_

ENA

Selects BCLK/GPIO4 pin function

0 = BCLK/GPIO4 is used as BCLK

1 = BCLK/GPIO4 is used as GPIO.

MCLK provides the BCLK in the AIF

in this mode.

3:0

GPIO_BCLK_SEL

[3:0]

0000

GPIO_BCLK function select:

0000 = Input Pin (default)

0001 = Clock output

(f=SYSCLK/OPCLKDIV)

0010 = Logic '0'

0011 = Logic '1'

0100 = IRQ

0101 = FLL Lock

0110 = Mic Detect

0111 = Mic Short

1000 = DMIC clock out

1001 = FLL Clock Output

1010 to 1111 = Reserved

Table 78 BCLK/GPIO4 Control

WM8904ECS/R 数据表(PDF) 117 Page - Wolfson Microelectronics plc

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