Pre-Production
WM8850
STEREO HEADPHONE PLAYBACK
Stereo headphone playback is supported using the VOUT1L and VOUT1R pins; these provide a
ground-referenced stereo output through the DAC1 node. This output is intended for headphones,
but can be used as a single-ended line output if required. This path can provide two channels of a
multi-channel playback system, operating alongside the other two DAC paths.
It is possible to configure the stereo headphone outputs to select the S/PDIF Rx node as the data
source. This signal path is enabled using a vendor-specific verb, and is illustrated by the dotted line in
Figure 11.
The WM8850 nodes associated with this function are shown in Figure 11.
from S/PDIF Rx
06h
11h
VOUT1L
VOUT1R
DAC1
Port-A
Figure 11 Stereo Headphone Playback Path
This section provides a summary of the DAC1 and Port-A, and describes the vendor-specific verb
functions associated with each.
DAC1 (NID = 06H)
Table 20 gives a summary of the DAC1 node:
NODE SUMMARY INFORMATION
NID
06h
Widget Type
Audio Converter
Supported Get Verbs
Supported Set Verbs
Unsolicited Responses
Vendor-Specific Verbs
Ah, Bh, F00h, F05h, F06h, F08h, F73h, F8Eh
2h, 3h, 705h, 706h, 708h, 773h, 78Eh
Stream Error
F73h, 773h : Internal Path Verb
F8Eh, 78Eh : Unsolicited Response Priority Control Verb
Table 20 DAC1 Node Summary Information
DAC1 is a high performance stereo DAC that supports all common sample rates from 8kHz to
192kHz and data widths of 16, 20, 24 and 32-bit (Float-32).
The sample rate and word length of the data played back by the DAC1 node is set using the Stream
Format Verb. Table 9 below shows the required settings for Base, Mult and Div as part of the Stream
Format Verb to obtain the required sample rate.
PP, April 2011, Rev 3.2
51
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
