WM8772EDS – 28 LEAD SSOP
Production Data
ADC AND DAC DIGITAL AUDIO INTERFACE CONTROL REGISTER
Interface format is selected via the FMT[1:0] register bits:
REGISTER ADDRESS
0000011
BIT
LABEL
FMT
DEFAULT
DESCRIPTION
1:0
00
Interface Format Select:
00 : Right justified mode
01: Left justified mode
10: I2S mode
Interface Control
[1:0]
11: DSP mode A or B
In left justified, right justified or I2S modes, the LRP register bit controls the polarity of LRC. If this bit
is set high, the expected polarity of LRC will be the opposite of that shown Figure 23, Figure 24 and
Figure 25. Note that if this feature is used as a means of swapping the left and right channels, a 1
sample phase difference will be introduced. In DSP modes, the LRP register bit is used to select
between mode A and mode B.
REGISTER ADDRESS
0000011
BIT
LABEL
DEFAULT
DESCRIPTION
In left/right/I2S Modes:
2
LRP
0
Interface Control
LRC Polarity (normal)
0 : Normal LRC polarity
1: Inverted LRC polarity
In DSP Mode:
0 : DSP mode A
1: DSP mode B
By default, LRC and DIN1/2/3 are sampled on the rising edge of BCLK and should ideally change on
the falling edge. By default, LRC and DOUT are sampled on the rising edge of BCLK and should
ideally change on the falling edge. Data sources that change LRC and DOUT on the rising edge of
BCLK can be supported by setting the BCP register bit. Data sources that change LRC and DIN1/2/3
on the rising edge of BCLK can be supported by setting the BCP register bit. Setting BCP to 1
inverts the polarity of BCLK to the inverse of that shown in Figure 23 to Figure 33.
REGISTER ADDRESS
0000011
BIT
LABEL
DEFAULT
DESCRIPTION
BCLK Polarity (DSP Modes):
0: Normal BCLK polarity
1: Inverted BCLK polarity
3
BCP
0
Interface Control
The IWL[1:0] bits are used to control the input word length.
REGISTER ADDRESS
0000011
BIT
LABEL
IWL
DEFAULT
DESCRIPTION
Input Word Length:
00 : 16 bit data
5:4
00
Interface Control
[1:0]
01: 20 bit data
10: 24 bit data
11: 32 bit data
Note: 32-bit right justified mode is not supported.
In all modes, the data is signed 2's complement. The digital filters always input 24-bit data. If the
DAC is programmed to receive 16 or 20 bit data, the WM8772EDS pads the unused LSBs with
zeros. If the DAC is programmed into 32 bit mode, the 8 LSBs are ignored.
Note: In 24 bit I2S mode, any width of 24 bits or less is supported provided that LRC is high for a
minimum of 24 BCLKs and low for a minimum of 24 BCLKs.
A number of options are available to control how data from the Digital Audio Interface is applied to
the DAC channels.
PD Rev 4.2 October 2005
32
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
