Pre-Production
WM8850
STEREO ANALOGUE MICROPHONE RECORD
Stereo analogue microphone input is supported using the VIN2LP, VIN2LN, VIN2RP and VIN2RN
pins; these are available for analogue microphone digitisation through the MIC1 node. The MICBIAS
output, controlled via the Port-B node, provides a low noise voltage output suitable for use as a power
supply for analogue or digital microphones.
The WM8850 nodes associated with this function are shown in Figure 7.
03h
09h
0Bh
0Dh
VIN2LP
VIN2LN
VIN2RP
VIN2RN
MIC1
MIC1 Mux
PGA2
Port-B
MICBIAS
from Port-D
Figure 7 Stereo Analogue Microphone Record Path
This section provides a summary of the Port-B, PGA2, MIC1 Mux and MIC1 nodes, and describes the
vendor-specific functions associated with each.
PORT-B (NID = 0DH)
Table 10 gives a summary of the Port-B node:
NODE SUMMARY INFORMATION
NID
0Dh
Widget Type
Pin Complex
Supported Get Verbs
Supported Set Verbs
Bh, F00h, F07h, F08h, F09h, F0Ch, F1Ch, F8Eh, FA3h, FB0h
3h, 707h, 708h, 70Ch, 71Ch, 71Dh, 71Eh, 71Fh, 78Eh, 7A3h,
7B0h
Unsolicited Responses
Vendor-Specific Verbs
Presence Detect Status Change
Impedance Measurement Ready
F8Eh, 78Eh : Unsolicited Response Priority Control Verb
FA3h, 7A3h : Differential Verb
FB0h, 7B0h : Auto-Mute Control Verb
Table 10 Port-B Node Summary Information
Port-B supports three different input configurations, controlled by the EAPD/BTL Verb and the vendor-
specific Differential Verb.
SET VERB
BIT
BITFIELD
NAME
DEFAULT
DESCRIPTION
70Ch
0
BTL
1h
Controls the configuration of the input pins on
Port-E:
0 = Single-ended mode
1 = BTL (balanced) mode
Differential mode:
7A3h
0
Differential
Mode
0h
0 = Differential (microphone)
1 = Pseudo-differential
PP, April 2011, Rev 3.2
43
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
