WM8994 datasheet(162/359 Pages) WOLFSON

162 / 359 page

WM8994

Production Data

PD, April 2012, Rev 4.4

162

DIGITAL AUDIO INTERFACE

The WM8994 provides digital audio interfaces for inputting DAC data and outputting ADC or Digital

Microphone data. Flexible routing options also allow digital audio to be switched or mixed between

interfaces without involving any DAC or ADC.

The WM8994 provides two full audio interfaces, AIF1 and AIF2. A third interface, AIF3, is partially

supported, using multiplexers to re-configure alternate connections to AIF1 or AIF2.

The digital audio interfaces provide flexible connectivity with multiple processors (eg. Applications

processor, Baseband processor and Wireless transceiver). A typical configuration is illustrated in

Figure 44.

Figure 44 Typical AIF Connections

In the general case, the digital audio interface uses four pins:



ADCDAT: ADC data output



DACDAT: DAC data input



LRCLK: Left/Right data alignment clock



BCLK: Bit clock, for synchronisation

In master interface mode, the clock signals BCLK and LRCLK are outputs from the WM8994. In slave

mode, these signals are inputs, as illustrated below.

As an option, a GPIO pin can be configured as the Left/Right clock for the ADC. In this case, the

LRCLK pin is dedicated to the DAC, allowing the ADC and DAC to be clocked independently.

Four different audio data formats are supported each digital audio interface:



Left justified



Right justified



DSP mode

All four of these modes are MSB first. They are described in the following sections. Refer to the

“Signal Timing Requirements” section for timing information.

WM8994 Datasheet(PDF) 162 Page - Wolfson Microelectronics plc