CS494002 datasheet(78/100 Pages) CIRRUS

78 / 100 page

10. HARDWARE CONFIGURATION

After download or soft reset, and before kickstart,

the host has the option of changing the default

hardware configuration. (Please see the Audio

Manager in the Application Messaging Section of

any Application Code User’s Guide for more

information on kickstarting.)

Hardware configuration messages are used to

physically reconfigure the hardware of the audio

decoder, as in enabling or disabling address

checking for the serial communication port.

Hardware configuration messages are also used to

initialize the data type (i.e., PCM or compressed)

and format (e.g., I2S, left justified, etc.) for digital

data inputs, as well as the data format and clocking

options for the digital output port.

In general, the hardware configuration can only be

changed immediately after download or after soft

reset

and

before

kickstart.

However,

some

applications provide the capability to change the

input ports without affecting other hardware

configurations, after sending a special Application

Restart message. (Please see the Audio Manager in

any Application Code User’s Guide to determine

whether the Application Restart message is

supported.)

11. DIGITAL INPUT AND OUTPUT

DATA FORMATS

The CS49400 supports a wide variety of data input

and output data formats through various input and

output ports. Hardware availability is entirely

dependent on whether the software application

code being used supports the required mode. This

data sheet presents most of the modes available

with the CS49400 hardware. This does not mean

that all of the modes are available with any

particular

piece

application

code.

The

Application Code User’s Guide for the particular

code being used should be referenced to determine

if a particular mode is supported. In addition if a

particular mode is desired that is not presented,

please contact your local FAE as to its availability.

11.1 Digital Audio Formats

This subsection will describe some common audio

formats that the CS49400 supports. It should be

noted that the input ports use up to 24-bit PCM

resolution and 16-bit compressed data word

lengths. The output port of the CS49400 provides

up to 24-bit PCM resolution.

11.1.1 I2S

Figure 55, "I2S Format" on page 79 shows the I2S

format. For I2S, data is presented most significant

bit first, one FSCLKN1 delay after the transition of

FLRCLKN1, and is valid on the rising edge of

FSCLKN1. For the I2S format, the left subframe is

presented when FLRCLKN1 is low; the right

subframe is presented when FLRCLKN1 is high.

FSCLKN1 is required to run at a frequency of 48Fs

or greater on the input ports.

11.1.2 Left Justified

Figure 56, "Left Justified Format (Rising Edge

Valid SCLK)" on page 79 shows the left justified

format with a rising edge FSCCLK. Data is

presented most significant bit first on the first

FSCLKN1 after an FLRCLKN1 transition and is

valid on the rising edge of FSCLKN1. For the left

justified format, the left subframe is presented

when FLRCLKN1 is high and the right subframe is

presented when FLRCLKN1 is low. The left

justified format can also be programmed for data to

be valid on the falling edge of FSCLKN1.

FSCLKN1 is required to run at a frequency of 48Fs

or greater on the input ports.

11.2 Digital Audio Input Port

The digital audio input port (DAI) on DSPAB, is

used for both compressed and PCM digital audio

data input. In addition this port supports a special

clocking mode in which a clock can be input to

directly drive the internal 33 bit counter. Table 18,

“Digital Audio Input Port,” on page 79 shows the

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