WM8716

Production Data

WOLFSON MICROELECTRONICS LTD

PD Rev 3.1 April 2001

10

MODES OF OPERATION

Control of the various modes of operation is either by software control over the serial interface, or

by hard-wired pin control. Selection of software or hardware mode is via MODE pin. The following

functions may be controlled either via the serial control interface or by hard wiring of the

appropriate pins.

HARDWARE CONTROL MODES

When the MODE pin is held ‘low’ the following hardware modes of operation are available. In

Hardware differential mode or 8X mode some of these modes/control words are altered or

unavailable.

DE-EMPHASIS CONTROL

MDDM1

PIN 27

MCDMO

PIN 26

DE-EMPHASIS

LL

Off

L

H

48kHz

H

L

44.1kHz

H

H

32kHz

Table 2 De-Emphasis Control

AUDIO INPUT FORMAT

CSBIIS

PIN 28

CSBIWO

PIN 23

DATA FORMAT

L

L

16 bit normal right justified

L

H

20 bit normal right justified

H

L

16 bit I

H

H

24 bit I

Table 3 Audio Input Format

SOFT MUTE

MUTEB

PIN 25

FUNCTION

L

Mute On (no output)

Z

Automute

H

Mute Off (normal operation)

Table 4 Soft Mute

A logic low on the MUTEB pin will cause the attenuation to ramp to infinite attenuation at a rate of

128/fs seconds per 0.5dB step. Setting MUTEB high will cause the attenuation to ramp back to its

previous value.

Leaving MUTEB undriven allows operation of the automute circuit in both hardware and software

modes. On receiving 1024 consecutive zero value audio samples, the analogue stage output mute is

asserted. This may be overdriven from the MUTEB pin to disable the automute function, or output as

a weak (10kohm) output signal.

SOFTWARE CONTROL INTERFACE

The WM8716 can be controlled using a 3-wire serial interface. MD/DM0 (pin 26) is used for the

program data, MC/DM1 (pin 22) is used to clock in the program data and ML/I2S (pin 28) is use to

latch in the program data. The 3-wire interface protocol is shown in Figure 6. CSB/IWO (pin 23) must

be low when writing.