Cirrus Logic CDB8420 User Manual

Evaluation Board for CS8420

CDB8420

Features



Asynchronous Sample Rate Conversion



Input to output conversion ratio as large as
1:3 or 3:1



Receives and transmits AES/EBU, S/PDIF
and EIAJ-340 compatible digital audio



Runs from a single 5 Volt supply.



Crystals are supplied to allow operation at

44.1 kHz, 48 kHz, and 96 kHz output sample
rates.



Digital patch area.

I

Description

The CDB8420 is de signed to allow rapid evaluation of
the CS8420. Because of the high performance of the
CS8420, the board is set up for e asy connection to an
Audio Precision or a Rohde and Schwarz test system.
Currently available A/D and D/A converters are not ade­quate to test the full performance of the device.

Input and output data may independently be set to either
AES/EBU or S/PDIF in optical or coaxial physical
formats.

Windows 98 PC software provides a GUI interface to
make configuration easy. The software communicates
through the PC’s RS232 port to a micro-controller on the
evaluation board that controls the CS8420. All the possi­ble software modes of the CS8420 may be tested.

ORDERING INFORMATION

CDB8420 Evaluation Board

Amtel

µC

Optical In

S/PDIF In

AES 3 In

Preliminary Product Information

http://www.cirrus.com

RS232 port to PC

Optical Out

CS8420

S/PDIF Out
AES 3 Out

This document contains information for a new product.
Cirrus Logic reserves the right to modify this product without notice.

Copyright  Cirrus Logic, Inc. 2003

(All Rights Reserved)

Dec ‘03

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TABLE OF CONTENTS

1. OVERVIEW ...............................................................................................................................3

1.1 CS8420 ............... .......... ................ .......... ......... ................. ......... .......... ................ ..............3

1.2 Micro-Controller and Memory ............................................................................................3

1.3 Crystal Oscil lators ......... ................................. .......... ......... ......... ................. ......... .............. 3

1.4 RS232 Port ......... .......... ................................. .......... ......... ................. ......... .......................3

1.5 LED Function Ind icators ..... ......... ................................. .......... ......... ................. ......... .........3

2. CDB8420.EXE QUICK START GUIDE ....................................................................................5

2.1 Setting up th e hard wa r e : ............... ................. .......... ......... ................. ......... .......................5

2.2 Installing the software: ....................................................................................................... 5

2.3 Starti ng u p the s of twar e : .................... ................. ......... .......... ................................. ...........5

2.4 Starti ng u p the Hardwa r e : ..................... ......... ................................. .......... ......... .......... ......5

3. CDB8420.EXE USER'S GUIDE ................................................................................................6

3.1 Main Window ........................................................................... ....... ....... ....... ..... ....... .........6

3.2 Board Setup .................... .......... ................ .......... ......... ................. ......... ............................7

3.3 Script fi l e synt ax .......................... .......... ......... ................. ......... .......... ....................... .........7

LIST OF FIGURES

Figure 1. CDB8420 Control Panel Main Window ............................................................................6

Figure 2. Board Setup Panel................................................................... .......... ......... ....... .............. 7

Figure 3. CS8420 Sample Rate Converter......................................................................................8

Figure 4. Atmel AVR RISC Micro-controller....................................................................................9

Figure 5. Power Supplies and Reset Circuit..................................................................................10

Figure 6. Silkscreen............... ................. ......... .......... ................................. ......... .......... ................11

Figure 7. Top PCB.........................................................................................................................12

Figure 8. Botto m PCB.................. ................................. .......... ......... ................. ......... .......... .........13

CDB8420

LIST OF TABLES

Table 1. System Connec tions ............. ................. ......... .......... ................ .......... ......... .....................4

Table 2. CDB8420 Jumper Settings................................................................................................4

Table 3. Script file syntax description..............................................................................................7

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1. OVERVIEW

CDB8420

The CDB8420 evaluation board contains a CS8420
and the supporting circuitry necessary for it to op­erate. The input and output options include AES3
and S/PDIF in optical and coaxial formats. In soft­ware 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 t o control the con­figuration.

1.1 CS8420

The features and functions of the CS8420 are de­scribed in its data sheet.

1.2 Micro-Controller and Memory

The functions of the board are controlled by an At­mel 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 . T he Atmel AVR RISC micro­controller may be bypassed in order to utilize an
external micro-controller through header J10. Ad­ditional software development tools and applica­tions information for the Atmel micro-controller
are available at http://www.atmel.com.

1.3 Crystal Oscillators

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 M aster
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.

There are two crystal oscillators on the board, both
are mounted in pin sockets that allow them to be re-

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CDB8420

CONNECTOR INPUT/OUTPUT SIGNAL PRESENT

+5V Input +5 Volt power

GND Input Ground connection from power supply

OPTICAL INPUT Input Digital Audio Interface optical input

S/PDIF INPUT Input Digital Audio Interface coaxial input

AES3 INPUT Input Digital Audio Interface XLR input

RS232 Input/Output Parallel RS232 port for connection to serial port of PC

OPTICAL OUTPUT Output Digital Audio Interface optical output (always active)

S/PDIF OUTPUT Output Digital Audio Interface coaxial output

AES3 OUTPUT Output Digital Audio Interface XLR output

J5 Input/Output I/O for RMCLK, ISCLK,ILRCK, and SDIN
J6 Input/Output I/O for OLRCK, OSCLK, OMCK, and SDOUT
J9 Input 10-pin header for external programming of Atmel AVR µC

J10 Input/Output 12-pin header for CS8420 control by external µC

Table 1. System Connections

JUMPER PURPOSE POSITION FUNCTION SELECTED

J11 Selects physical format of digital

audio interface input

J12 Enables AES3 INPUT ENABLE

J13 Enables S/PDIF INPUT ENABLE

J14 Enables OPTICAL INPUT ENABLE

J16 Selects physical format of digital

audio interface output

J17 Enables S/PDFIF OUTPUT ENABLE

J15 Enables HARDWARE MODE MUTE ENABLE

Table 2. CDB8420 Jumper Settings

AES3 & S/PDIF

OPTICAL

DISABLE

DISABLE

DISABLE

AES3

S/PDIF

DISABLE

DISABLE

Specifies input as either AES3 or S/PDIF type
Specifies input as OPTICAL type
AES3 INPUT enabled
AES3 INPUT disabled
S/PDIF INPUT enabled
S/PDIF INPUT disabled
OPTICAL INPUT enabled
OPTICAL INPUT disabled
Specifies output as AES3 XLR
Specifies output as coaxial S/PDIF

S/PDIF OUTPUT enabled
S/PDIF OUTPUT disabled
Enables MUTE when in hardware mode 1
Disables MUTE when in hardware mode 1

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CDB8420

2. CDB8420.EXE QUICK START GUIDE

2.1 Setting up the hardware:

1) Connect the CDB8420 to a 5V DC power sup­ply.

2) Set: J11 to Optical, J16 to S/PDIF, enable J13
(S/PDIF), and disable J15 (MUTE).

3) Connect the CDB8420 to the PC COM port us­ing RS232 cable.

4) Apply power to the board.

5) Press the RESET switch (S5).

At this point, the RERR and PROC should be lit.
The hardware is now ready!

2.2 Installing the software:

1) Create a directory called CDB8420 anywhere
on your system.

2) Copy CDB8420.exe into this directory.

3) If you do not already have them, copy the in­cluded DLLs msvcrt.dll and mfc42.dll into
your \Windows\System directory.

4) If desired, create a sho rtcut to CDB8420.exe on
your desktop.

At this point, you are ready to start up the software.

2.3 Starting up the software:

1) Double-click on CDB8420.exe or its shortcut.

2) If you get errors right away, the COM port
needs to be set properly.

3) Click anywhere but inside one of the boxes, this
brings up the Board Setup control panel.

4) Select the COM port you are using to connect
to the CDB8420.

5) Shut down the application, reset the board, and
then restart the application.

2.4 Starting up the Hardware:

1) Click anywhere but inside one of the boxes, this
brings up the Board Setup control panel.

2) Click on the Reset button. You should see the
TX and RX leds light up briefly.

3) Click on the Sample Rate Converter tab, then
set the SRC data source to AES3 Receiver.

4) Click on the Clock Sources tab, uncheck the
Stop Internal Clocks box and click on RMCK
derived from AES3 input frame.

5) Check the performance of the board by doing
an FFT with a -1dBFS 1kHz sine w ave for in­put at 44.1kHz and 48kHz sample rates using
the optical input and optical output.

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