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.
from PGA2
03h
09h
0Eh
DMICDAT1
DMICCLK
MIC1
MIC1 Mux
Port-D
from S/PDIF Tx 2
15h
16h
DMICDAT2/
SPDIFOUT2
MIC2
Port-H
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.
PP, April 2011, Rev 3.2
48
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
