CS4201 Datasheet, PDF (40/68 Pages) Cirrus Logic – CrystalClear Audio Codec 97 with headphone Amplifier

CS4201
5. SERIAL DATA PORTS
5.1 Overview
The CS4201 implements two serial data output
ports that can be used for multi-channel expansion.
Each serial port consists of 4 signals: MCLK,
SCLK, LRCLK, and SDATA. The existing 256 Fs
BIT_CLK will be used as MCLK. The clock pins
are shared between all the serial ports with only the
SDATA pins being separate; SDOUT for the first
output port, and SDO2 for the second output port.
Serial data is transmitted on these ports every
AC-link frame.
The serial data port is controlled by the SDEN,
SDSC,and SDO2 bits in the Serial Port Control
Register (Index 6Ah). All the serial data port pins
are multiplexed with other functions and cannot be
used unless the other function is disabled or pow-
ered down; see Section 7, Exclusive Functions.
Some audio DACs can run in an internal SCLK
mode where SCLK is internally derived from
MCLK and LRCLK. In this case, SCLK generation
in the CS4201 is optional.
A feature has been designed into the CS4201 that
allows the phase of the internal DACs to be re-
versed. This DAC phase reversal is controlled by
the DPC bit in the Misc. Crystal Control Register
(Index 60h). This feature is necessary since the
phase response for external DACs is unknown and
the phase response of the internal DACs can vary
depending on the path determined by the POP bit in
the General Purpose Register (Index 20h), the
DDM bit in the AC Mode Control Register
(Index 5Eh), and the output (LINE_OUT or
HP_OUT) being used. This feature guarantees that
all DACs in a system have the same phase re-
sponse, maintaining the accuracy of spatial cues.
Please note the data sent to the serial ports is
straight from the AC-link. There is no SRC and no
volume control available on this data, so it is the re-
sponsibility of the controller or host software to
provide this functionality if desired.
5.2 Multi-Channel Expansion
For multi-channel expansion, the two serial data
output ports are used to send AC-link data to one or
two external stereo DACs to support up to a total of
six channels. The first serial port takes the digital
audio data from the SDOUT slots. The second seri-
al port takes the digital audio data from the SDO2
slots. See Table 10 on page 35 for the actual slots
used depending on configuration. Figure 10 shows
a six channel application using the CS4201.
LINE_OUT_L ³⁵
LINE_OUT_R ³⁶
GPIO1/SDOUT
EAPD/SCLK
GPIO0/LRCLK
BIT_CLK
SPDO/SDO2
44
47
43
6
48
10uF
+ ELEC
10uF
+ ELEC
Left Front
Right Front
1000pF 1000pF
CS4334
1
2
3
4
SDATA
DEM#/SCLK
LRCK
MCLK
AOUTL
AOUTR
8
5
AGND
+
10uF
ELEC
10uF
+ ELEC
270K 270K
47K
220K 220K
AGND
560
560
Left Surround
Right Surround
47K
2700pF 2700pF
CS4334
1
2
3
4
SDATA
AOUTL
DEM#/SCLK
LRCK
MCLK
AOUTR
8
5
AGND
10uF
+ ELEC
10uF
+ ELEC
AGND
560
560
270K 270K
47K 47K
AGND
Center
LFE
2700pF 2700pF
AGND
AGND
AGND
Figure 10. Serial Data Port: Six Channel Circuit
40
DS483PP3