WM8959 datasheet(112/155 Pages) WOLFSON

112 / 155 page

WM8959

Pre-Production

PP, May 2008, Rev 3.1

112

CONTROL INTERFACE

The WM8959 is controlled by writing to its control registers. Readback is available for certain

registers, including device ID, power management registers and some GPIO status bits. The control

interface can operate as either a 2-, 3- or 4-wire control interface, with additional variants as detailed

below:

2-wire

- open-drain

3-wire

- push 0/1

- open drain

4-wire

- push 0/1

- wired-OR

Readback is provided on the bi-directional pin SDIN in 2-/3-wire modes and on a GPIO pin in 4-wire

mode.

SELECTION OF CONTROL MODE AND 2-WIRE MODE ADDRESS

MODE pin determines the 2- or 3-/4-wire mode as shown in Table 66.

MODE

INTERFACE FORMAT

Low

2 wire

High

3- or 4- wire

Table 66 Control Interface Mode Selection

2-WIRE SERIAL CONTROL MODE

The WM8959 is controlled by writing to registers through a 2-wire serial control interface. A control

word consists of 24 bits. The first 8 bits (B23 to B16) are address bits that select which control

each control register. Many devices can be controlled by the same bus, and each device has a

unique 7-bit address (this is not the same as the 8-bit address of each register in the WM8959). The

default device address is 0011010 (0x34h).

The WM8959 operates as a slave device only. The controller indicates the start of data transfer with

a high to low transition on SDIN while SCLK remains high. This indicates that a device address and

data will follow. All devices on the 2-wire bus respond to the start condition and shift in the next eight

bits on SDIN (7-bit address + Read/Write bit, MSB first). If the device address received matches the

address of the WM8959, then the WM8959 responds by pulling SDIN low on the next clock pulse

(ACK). If the address is not recognised or the R/W bit is ‘1’ when operating in write only mode, the

WM8959 returns to the idle condition and wait for a new start condition and valid address.

The WM8959 supports a multitude of read and write operations, which are:

•

Single write

•

Single read

•

Multiple write using auto-increment

•

Multiple read using auto-increment

WM8959 Datasheet(PDF) 112 Page - Wolfson Microelectronics plc

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