CDB8420 datasheet(3/14 Pages) CIRRUS

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CDB8420

DS245DB4

OVERVIEW

The CDB8420 evaluation board contains a CS8420

and the supporting circuitry necessary for it to op-

erate. The input and output options include AES3

and S/PDIF in optical and coaxial formats. In soft-

ware mode, the control registers of the CS8420 are

set by an Atmel AVR RISC micro-controller. A

Windows 98 based program communicates with

the micro through an RS232 port to control the con-

figuration.

1.1

CS8420

The features and functions of the CS8420 are de-

scribed in its data sheet.

1.2

Micro-Controller and Memory

The functions of the board are controlled by an At-

mel AVR RISC micro-controller. The board is

equipped with 512 kilobytes of static RAM so that

Channel Status and User bits from the AES stream

may be captured and uploaded to the host PC. The

micro-controller communicates with the CS8420

through its SPI port. The Atmel AVR RISC micro-

controller may be bypassed in order to utilize an

external micro-controller through header J10. Ad-

ditional software development tools and applica-

tions information for the Atmel micro-controller

are available at http://www.atmel.com.

1.3

Crystal Oscillators

There are two crystal oscillators on the board, both

are mounted in pin sockets that allow them to be re-

placed. The oscillator labeled U10 provides the 6

MHz clock for the micro-controller and should not

be changed.

U3 is the oscillator that provides the Output Master

Clock for the CS8420. The board is shipped with a

12.288 MHz crystal oscillator stuffed at U3 which

sets the output sampling rate to 48 kHz.

Oscillators are also provided for the frequencies of

11.2896 and 24.576 MHz. These allow the SRC to

be operated at output sampling frequencies of 44.1

and 96 kHz.

1.4

RS232 Port

The RS232 port on the upper right hand side of the

board should be connected to the serial port of the

PC running the CDB8420 control software. Follow

the software instructions to properly configure the

serial port for use with the evaluation board.

1.5

LED Function Indicators

LEDs D8 and D9 on the upper right hand corner of

the board allow the user to determine when data is

being transmitted over the RS232 link. The red

LED D4 is the reset indicator and the red LED D1

is connected to the RERR pin of the CS8420. The

two remaining LEDs on the board are not currently

of use to the end user.

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