Overview; Cs8427; Micro-Controller And Memory; Crystal Oscillators - Cirrus Logic Crystal CDB8427 Manual

1. OVERVIEW

The CDB8427 evaluation board contains a CS8427
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 CS8427 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

CS8427

The features and functions of the CS8427 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 CS8427
through its SPI port. The Atmel AVR RISC micro-
controller may be bypassed in order to utilize an
external micro-controller through header J10.
Header J9 allows the micro-controller on the board
to be programmed with the programmer that is sup-
plied in the Atmel STK-300 development kit. Ad-
ditional software
DS477DB1
development tools
applications information for the Atmel micro-con-
troller are available at http://www.atmel.com.
1.3

Crystal Oscillators

There are positions for two crystal oscillators on
the board. Both locations are equiped with pin
sockets that allow the oscillators to be removed.
The oscillator labeled U10 provides the 6 MHz
clock for the micro-controller and should not be
changed unless you plan on reprogramming the mi-
cro.
U3 is the oscillator that provides the Output Master
Clock for the CS8427. The board is shipped with a
12.288 MHz crystal oscillator that can be stuffed at
U3 to set the output sampling rate to 48 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 CDB8427 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 CS8427. The
and
two remaining LEDs on the board are not currently
of use to the end user.
CDB8427
3