wm8988 Wolfson Microelectronics plc, wm8988 Datasheet - Page 37

• Manufacturer Part Number: wm8988
• Description: Stereo Codec For Portable Audio Applications
• Manufacturer: Wolfson Microelectronics plc

Production Data
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AUDIO INTERFACE CONTROL
The register bits controlling audio format, word length and master / slave mode are summarised in
Table 31. MS selects audio interface operation in master or slave mode. In Master mode BCLK and
LRC are outputs. The frequency of LRC is set by the sample rate control bits SR[4:0] and USB. In
Slave mode BCLK and LRC are inputs.
Table 31 Audio Data Format Control
AUDIO INTERFACE OUTPUT TRISTATE
Register bit TRI, register 24(18h) bit[3] can be used to tristate the ADCDAT pin and switch ADCLRC,
DACLRC and BCLK to inputs. In Slave mode (MASTER=0) LRC and BCLK are by default configured
as inputs and only ADCDAT will be tri-stated, (see Table 32).
Table 32 Tri-stating the Audio Interface
R24(18h)
Additional
Control (2)
R7 (07h)
Digital Audio
Interface
Format
REGISTER
REGISTER
ADDRESS
ADDRESS
BIT
7
6
5
4
3:2
1:0
BIT
3
LABEL
BCLKINV
MS
LRSWAP
LRP
WL[1:0]
FORMAT[1:0]
TRI
LABEL
DEFAULT
0
0
0
0
0
10
10
DEFAULT
Tristates ADCDAT and switches ADCLRC,
DACLRC and BCLK to inputs.
0 = ADCDAT is an output, LRC and BCLK are
inputs (slave mode) or outputs (master mode)
1 = ADCDAT is tristated, LRC and BCLK are
inputs
BCLK invert bit (for master and slave
modes)
0 = BCLK not inverted
1 = BCLK inverted
Master / Slave Mode Control
1 = Enable Master Mode
0 = Enable Slave Mode
Left/Right channel swap
1 = swap left and right DAC data in
audio interface
0 = output left and right data as normal
right, left and i2s modes – LRCLK
polarity
1 = invert LRCLK polarity
0 = normal LRCLK polarity
DSP Mode – mode A/B select
1 = MSB is available on 1
edge after LRC rising edge (mode B)
0 = MSB is available on 2
edge after LRC rising edge (mode A)
Audio Data Word Length
11 = 32 bits (see Note)
10 = 24 bits
01 = 20 bits
00 = 16 bits
Audio Data Format Select
11 = DSP Mode
10 = I
01 = Left justified
00 = reserved (do not use this setting)
2
S Format
DESCRIPTION
DESCRIPTION
PD, Rev 4.0, October 2008
st
nd
BCLK rising
BCLK rising
WM8988
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