WM8750BL Datasheet, PDF (26/59 Pages) Wolfson Microelectronics plc – Stereo CODEC for Portable Audio Applications

WM8750BL
Pre-Production
3D STEREO ENHANCEMENT
The WM8750BL has a digital 3D enhancement option to artificially increase the separation between
the left and right channels. This effect can be used for recording or playback, but not for both
simultaneously. Selection of 3D for record or playback is controlled by register bit MODE3D.
Important:
Switching the 3D filter from record to playback or from playback to record may only be done
when ADC and DAC are disabled. The WM8750BL control interface will only allow MODE3D to
be changed when ADC and DAC are disabled (i.e. bits ADCL, ADCR, DACL and DACR in reg.
26 / 1Ah are all zero).
The 3D enhancement function is activated by the 3DEN bit, and has two programmable parameters.
The 3DDEPTH setting controls the degree of stereo expansion. Additionally, one of four filter
characteristics can be selected for the 3D processing, using the 3DVC and 3DLC control bits.
REGISTER
ADDRESS
R16 (10h)
3D enhance
BIT
LABEL
7
MODE3D
6
3DUC
5
3DLC
4:1 3DDEPTH
[3:0]
0
3DEN
Table 15 3D Stereo Enhancement Function
DEFAULT
DESCRIPTION
0
0
0
0000
0
Playback/Record 3D select
0 = 3D selected for Record
1 = 3D selected for Playback
Upper Cut-off frequency
0 = High (2.2kHz at 48kHz
sampling)
1 = Low (1.5kHz at 48kHz sampling)
Lower Cut-off frequency
0 = Low (200Hz at 48kHz sampling)
1 = High (500Hz at 48kHz sampling)
Stereo depth
0000: 0% (minimum 3D effect)
0001: 6.67%
....
1110: 93.3%
1111: 100% (maximum 3D effect)
3D function enable
1: enabled
0: disabled
When 3D enhancement is enabled (and/or the graphic equaliser for playback) it may be necessary to
attenuate the signal by 6dB to avoid limiting. This is a user selectable function, enabled by setting
ADCDIV2 for the record path and DACDIV2 for the playback path.
REGISTER
ADDRESS
R5 (05h)
ADC and DAC
control
BIT
8
7
LABEL DEFAULT
ADCDIV2 0
DACDIV2 0
Table 16 ADC and DAC 6dB Attenuation Select
DESCRIPTION
ADC 6dB attenuate enable
0 = disabled (0dB)
1 = -6dB enabled
DAC 6dB attenuate enable
0 = disabled (0dB)
1 = -6dB enabled
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Pre-Production Rev 3.3 January 2007
26