Cirrus Logic CS4970x4 - Manual (Page 75)

Introduction
CS4953x4/CS4970x4 System Designer’s Guide
DS810UM6 Copyright 2013 Cirrus Logic, Inc 4-1
Chapter 4
Audio Output Interface
4.1 Introduction
The CS4953x4/CS4970x4 has two output ports - Digital Audio Output port 1 & 2 (DAO1 & DAO2). Each
port can output 8 channels of up to 32-bit PCM data. The Digital Audio Output ports are both implemented
with a modified 3-wire Inter-IC Sound (I
2
S) interface along with an oversampling Master clock (MCLK).
The I
2
S interface includes a frame clock at the current sampling frequency (LRCLK), a bit clock for
clocking the bits of the audio word (SCLK), and 4 audio data output signals (DATA[3:0]). Each of the
output data signals can be connected to the digital stereo input of an audio digital-to-analog converter
(DAC) for up to 8 channels of stereo PCM output per DAO port for a total of 16 digital audio output
channels.
Each DAO port may Slave to an externally generated SCLK and LRCLK or it may Master these clocks if
MCLK is provided. Each port can be configured as having an independent clock domain in Slave mode, or
the ratio of the two clocks can be set to even multiples of each other in Master mode. Additionally, the two
ports can be ganged together into a single clock domain. The port supports data rates from 32 KHz to
192 KHz. Each port can also be configured to provide a 32-KHz to 192-KHz S/PDIF transmitter (XMTA
and XMTB) as an output.
Figure 4-1 illustrates the DAO block diagram.
4.2 Digital Audio Output Port Description
4.2.1 DAO Pin Description
Figure 4-1 identifies the pins associated with the Digital Audio Output Ports (DAO1 and DAO2).
DAO_MCLK is the Master clock and is firmware configurable to be either an input (Slave) or an output
(Master). If MCLK is to be used as an output, the internal PLL must be used. As an output MCLK can be
configured to provide a 128Fs, 256Fs, or 512Fs clock, where Fs is the output sample rate.
Table 4-1. Digital Audio Output (DAO1 & DAO2) Pins
Pin Name Pin Description
LQFP-144
Pin #
LQFP-128
Pin #
Pin Type
DAO1_LRCLK Sample Rate Clock 22 54 I/O
DAO1_SCLK Bit Clock 20 52 I/O
DAO1_DATA0 Digital Audio Output 19 51 Output
DAO1_DATA1 Digital Audio Output 17 49 Output
DAO1_DATA2 Digital Audio Output 16 48 Output
DAO1_DATA3/XMTA Digital Audio Output 15 47 Output
DAO2_LRCLK Sample Rate Clock 14 46 I/O
DAO2_SCLK Bit Clock 12 44 I/O
DAO2_DATA0 Digital Audio Output 11 43 Output
DAO2_DATA1 Digital Audio Output 7 39 Output
DAO2_DATA2 Digital Audio Output 6 38 Output
DAO2_DATA3/XMTB Digital Audio Output 5 35 Output
DAO_MCLK Master Clock 8 40 I/O