WM8959 datasheet(84/155 Pages) WOLFSON

84 / 155 page

WM8959

Pre-Production

PP, May 2008, Rev 3.1

SERIAL DATA OUTPUT (REGISTER READBACK)

The GPIO pins can be configured to output serial data during register readback in 3-wire (open-drain)

or 4-wire mode. The readback mode is configured using the register bits RD_3W_ENA and

MODE_3W4W as described in Table 48.

Setting the RD_3W_ENA bit to 1 enables 3-wire readback using the SDIN pin in open-drain mode.

Setting the RD_3W_ENA bit to 0 requires the use of a GPIO pin as SDOUT. To enable SDOUT on a

GPIO pin, the following register settings are required:

•

GPIO1_ENA = 1 (only required if using GPIO1)

•

AIF_SEL = 0 (only required if using GPIO3, GPIO4 or GPIO5)

•

AIF_TRIS = 0

•

GPIOn_SEL = 0110 for the selected SDOUT output pin

•

GPIOn_PU = 0 for the selected SDOUT output pin

•

GPIOn_PD = 0 for the selected SDOUT output pin

The register fields used to configure SDOUT on the GPIO pins are described in Table 48. Refer to

“Control Interface” for more details of 3-wire and 4-wire interfacing.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

RD_3W_ENA

3- / 4-wire readback configuration

1 = 3-wire mode

0 = 4-wire mode, using GPIO pin

R22 (16h)

MODE_3W4W

3-wire mode

0 = push 0/1

1 = open-drain

4-wire mode

0 = push 0/1

1 = wired-OR

Table 48 GPIO 3-Wire Readback Enable

WM8959 Datasheet(PDF) 84 Page - Wolfson Microelectronics plc

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