Datasheet
ADAU1381
Rev. B | Page 53 of 84
SERIAL PORT CONFIGURATION
Register 16405 (0x4015), Serial Port Control 0
Bit 5, LRCLK Mode
This bit sets the serial port frame clock (LRCLK) as either a
50% duty cycle waveform or a pulse synchronization waveform.
When in slave mode, the pulse should be at least 1 BCLK cycle
wide to guarantee proper data transfer.
Bit 4, BCLK Polarity
This bit sets the polarity of the bit clock (BCLK) signal. This
setting determines whether the data and frame clock signals
change on a rising (+) or falling (−) edge of the BCLK signal
(see Figure 57). Standard I
2
S signals use negative BCLK polarity.
Bit 3, LRCLK Polarity
The polarity of LRCLK determines whether the left stereo channel
is initiated on a rising (+) or falling (−) edge of the LRCLK signal
(see Figure 58). Standard I
2
S signals use negative LRCLK polarity.
Bits[2:1], Channels per Frame
These bits set the number of channels contained in the data stream
(see Figure 59). The possible choices are stereo (used in standard
I
2
S signals), TDM 4 (a 4-channel time division multiplexed stream),
or TDM 8 (an 8-channel time division multiplexed stream). The
TDM output modes are simply multichannel data streams, and
the data pin does not become high impedance during periods
when it is not outputting data.
Within a TDM stream, channels are grouped by pair, as shown
in Figure 60.
Bit 0, Serial Data Port Mode
This bit sets the clock pins as either master or slave. Both
LRCLK and BCLK are the bus master of the serial port when
master mode is enabled.
Table 40. Serial Port Control 0 Register
Bits Description Default
[7:6] Reserved
5 LRCLK mode 0
0: 50% duty cycle clock
1: pulse mode; pulse should be at least 1 BCLK wide
4 BCLK polarity 0
0: data changes on falling (−) edge
1: data changes on rising (+) edge
3 LRCLK polarity 0
0: left frame starts on falling (−) edge
1: left frame starts on rising (+) edge
[2:1] Channels per frame 00
00: stereo (two channels)
01: TDM 4 (four channels)
10: TDM 8 (eight channels)
11: reserved
0 Serial data port mode 0
0: slave
1: master