WM8850 View Datasheet(PDF) - Wolfson Microelectronics plc

Part Name

Description

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WM8850

Multi-Channel High Definition Audio CODEC

Wolfson Microelectronics plc 

WM8850

Pre-Production

DIGITAL MICROPHONE RECORD

Digital microphone input is supported using the DMICDAT1, DMICDAT2 and DMICCLK pins; these

allow up to four independent digital microphones to be connected through the MIC1 and MIC2 nodes.

The digital microphone interface accepts unfiltered PDM on the DMICDAT1 and DMICDAT2 pins and

can recover data from both the high and low periods of the DMICCLK. Two microphone channels are

interleaved on DMICDAT1; another two channels are interleaved on DMICDAT2. The timing is

illustrated in Figure 9. Each microphone must tri-state its data output when the other microphone is

transmitting.

Note that the DMICDAT2 pin also supports the SPDIFOUT2 function, which is described in the

“S/PDIF Transmit” section.

Figure 9 Digital Microphone Interface Protocol for One (left) or Four (right) Microphones

The WM8850 nodes associated with this function are shown in Figure 10.

03h

MIC1

09h

MIC1 Mux

from PGA2

0Eh

Port-D

15h

MIC2

from S/PDIF Tx 2

16h

Port-H

DMICDAT1

DMICCLK

DMICDAT2/

SPDIFOUT2

from S/PDIF In

Figure 10 Digital Microphone Record Path

This section provides a summary of the Port-D, Port-H and MIC2 nodes, and describes the vendor-

specific verb functions associated with each.

The MIC1 Mux and MIC1 nodes are described in the “Stereo Analogue Microphone Record” section.

w

PP, April 2011, Rev 3.2

48

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