Production Data
WM8750L
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) ADCLRC, DACLRC and BCLK are by
default configured as inputs and only ADCDAT will be tri-stated, (see Table 35).
REGISTER
ADDRESS
BIT
LABEL DEFAULT
TRI
DESCRIPTION
R24(18h)
Additional
Control (2)
Tristates ADCDAT and switches ADCLRC,
DACLRC and BCLK to inputs.
3
0
0 = ADCDAT is an output, ADCLRC, DACLRC
and BCLK are inputs (slave mode) or outputs
(master mode)
1 = ADCDAT is tristated, ADCLRC, DACLRC
and BCLK are inputs
Table 35 Tri-stating the Audio Interface
MASTER MODE ADCLRC AND DACLRC ENABLE
In Master mode, by default ADCLRC is disabled when the ADC is disabled and DACLRC is disabled
when the DAC is disabled. Register bit LRCM, register 24(18h) bit[2] changes the control so that the
ADCLRC and DACLRC are disabled only when ADC and DAC are disabled. This enables the user to
use e.g. ADCLRC for both ADC and DAC LRCLK and disable the ADC when DAC only operation is
required, (see Table 36).
REGISTER
ADDRESS
BIT
LABEL DEFAULT
LRCM
DESCRIPTION
R24(18h)
Additional
Control (2)
Selects disable mode for ADCLRC and
DACLRC
2
0
0 = ADCLRC disabled when ADC (Left and
Right) disabled, DACLRC disabled when
DAC (Left and Right) disabled.
1 = ADCLRC and DACLRC disabled only when
ADC (Left and Right) and DAC (Left and
Right) are disabled.
Table 36 ADCLRC/DACLRC Enable
BIT CLOCK MODE
The default master mode bit clock generator produces a bit clock frequency based on the sample rate
and input MCLK frequency as shown in Table 40. When enabled by setting the appropriate BCM[1:0]
bits, the bit clock mode (BCM) function overrides the default master mode bit clock generator to
produce the bit clock frequency shown in the table below:
REGISTER
ADDRESS
BIT
LABEL DEFAULT
00
DESCRIPTION
R8 (08h)
BCLK Frequency
8:7 BCM[1:0]
Clocking and
Sample Rate
Control
00 = BCM function disabled
01 = MCLK/4
10 = MCLK/8
11 = MCLK/16
Table 37 Master Mode BCLK Frequency Control
The BCM mode bit clock generator produces 16 or 24 bit clock cycles per sample. The number of bit
clock cycles per sample in this mode is determined by the word length bits (WL[1:0]) in the Digital
Audio Interface Format register (R7). When these bits are set to 00, there will be 16 bit clock cycles
per sample. When these bits are set to 01, 10 or 11, there will be 24 bit clock cycles per sample.
Please refer to Figure 25.
PD, Rev 4.4, August 2012
45
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
