Cirrus Logic CS4953xx - Manual (Page 69)

7-3 Copyright 2010 Cirrus Logic, Inc. DS732UM10
Digital Audio Output Port Description
CS4953xx Hardware User’s Manual
7.1.2 Supported DAO Functional Blocks
As mentioned earlier in the previous section, two DAO ports, DAO1_DATA3 and DAO2_DATA3, are
unique in that they are designed to serve as either an output for I
2
S or left-justified PCM data or as S/PDIF
transmitters (XMTA and XMTB). When configured as S/PDIF transmitters, the ports encode digital audio
data according to the Sony
®
/Philips
®
Digital Interface Format (S/PDIF), also known as IEC60958, or the
AES/EBU interface format. Please see Figure 7-1 for a block diagram of the supported functional blocks
for the DAO on the CS4953xx
7.1.3 DAO Interface Formats
The DAO interface has 8 stereo data outputs that are fully configurable including support for I
2
S, left-
justified, and multichannel (one-line data mode) formats. This section describes some common audio
formats that the CS4953xx DAO interface supports. It should be noted that the digital output ports provide
up to 32-bit PCM resolution.
Note: DAO1_DATAx is valid with respect to DAO1_SCLK/DAO1_LRCK and DAO2_DATAx is valid
with respect to DAO2_SCLK/DAO2_LRCK
7.1.3.1 I
2
S Format
In this format, data is presented most-significant bit (MSB) first, one DAO_SCLK delay after the transition
of DAO_LRCLK, and is valid on the rising edge of DAO_SCLK. The left subframe is presented when
DAO_LRCLK is low, and the right subframe is presented when DAO_LRCLK is high.
Figure 7-2 provides
details on I
2
S compatible (maximum of 32 bits) serial audio formats.
Figure 7-2. I
2
S Compatible Serial Audio Formats (Rising Edge Valid)
7.1.3.2 Left-Justified Format
Figure 7-3 illustrates the left-justified (LJ) format with a rising edge DAO_SCLK. Data is presented most-
significant bit first on the first DAO_SCLK after a DAO_LRCLK transition and is valid on the rising edge of
DAO_SCLK. The left subframe is presented when DAO_LRCLK is high and the right subframe is
presented when DAO_LRCLK is low. This format can also be programmed for data to be valid on the
falling edge of DAO_SCLK.
Figure 7-3. Left-justified Digital Audio Formats (Rising Edge Valid DAO_SCLK)
DAO_LRCLK
DAO_SCLK
Left Channel Right Channel
DAO_DATA +3 +2 +1 LSB +5 +4 MSB-1 -2 -3 -4 -5 +3 +2 +1 LSB +5 +4 MSB-1 -2 -3 -4
DAO_LRCLK
DAO_SCLK
L e ft C h a n n e l R i g ht C h a n n el
DAO_DATA +3 +2 +1 LSB +5 +4 MSB -1 -2 -3 -4 -5 +3 +2 +1 +5 +4 -1 -2 -3 -4 LSB MSB