Cirrus Logic CDB5529 User Manual

CDB5529

CDB5529 Evaluation Board and Software

Features

l

RS-232 Serial Communication with PC

l

On-board 80C51 Microcontroller

l

On-board Voltage Reference

l

Lab Windows/CVITM Evaluation
Software

- Register Setup & Chip Control

- FFT Analysis

- Time Domain Analysis

- Noise Histogram Analysis

l

Integrated RS-232 Test Mode

General Description

The CDB5529 is an inexpensive tool designed to evalu­ate the performance of the CS5529 16-bit Analog-to­Digital Converter (ADC).

The evaluation board includes an LT1019 voltage refer­ence, an 80C51 microcontroller, an RS232
driver/receiver, and firmware. The 8051 controls the se­rial communication between the evaluation board and
the PC via the firmware, thus, enabling quick and easy

access to all of the CS5529’s registers.
The CDB5529 also includes software for Time Domain

Analysis, Histogram Analysis, and Frequency Domain
Analysis.

ORDERING INFORMATION: CDB5529

+5/+2.5 ANALOG -2.5 ANALOG AGND DGND +5/3.3 DIGITAL

VOLTAGE

REFERENCE

J1

REF+

AIN+

AIN-

REF-

AIN+

AIN-

CRYSTAL
32768Hz

Cirrus Logic, Inc.
Crystal Semiconductor Products Division

P.O. Box 17847, Austin, Texas 78760
[phone] FAX: [phone]
http://www.crystal.com

CS5529

CS

SDI

SDO

SCLK

D3
D2
D1

D0

A1
A0

XINXOUT

LEDs

80C51

MICROCONTROLLER

123

ON

OFF

TEST

SWITCHES

HDR6

Copyright  Cirrus Logic, I nc. 1997

(All Rights Reserv ed)

+5 DIGITAL

RS232

CONNECTOR

RS232

DRIVER/RECEIVER

CRYSTAL

11.0592MHz

RESET

CIRCUITRY

AUG ‘97

DS246DB1

1

CDB5529

PART I: HARDWARE

Introduction

The CDB5529 evaluation board provides a quick
means of testing the CS5529 Analog-to-Digital
Converter (ADC). The board interfaces the

TM

CS5529 to an IBM
RS-232 interface while operating from either a sin-

gle +5 V supply or dual ±2.5 volt supplies. To ac­complish this, the board comes equipped with an
80C51 microcontroller and a 9-pin RS-232 cable
which physically interfaces the evaluation board to
the PC. Additionally, analysis software provides
easy access to the internal registers of the convert­er, and provides a means to display the converter’s
time domain, frequency domain, and noise histo­gram performance. The evaluation board’s soft­ware includes debug algorithms to trouble shoot
the evaluation board. Refer to the Trouble Shoot -
ing the Evaluation Board section for more details.

compatible PC via an

The evaluation board provides two voltage refer­ence options, on-board and external. With HDR5’s
jumpers in positions 1 and 4, the LT1019 provides
an absolute voltage level of 2. 5 volts (the LT1019
was chosen for its low drift, typically 5ppm/°C). By
setting HDR5’s jumpers to position 2 and 3, the
user can supply an external voltage reference to
J1’s REF+ and REF- inputs (Application Note 4 on
Crystal Semiconductor’s web site details various
voltage references).

TM

The ADC serial interface is SPI

TM

MICROWIRE

lines (CS
the 80C51 microcontroller via port one. To inter­face an external microcontroller, these control lines
are also connected to HDR6. However to accom­plish this, the evaluation board must be modified in
one of three ways: 1) cut the interface control traces
going to the microcontroller, 2) remove resistors
R1-R8, or 3) remove the microcontroller.

, SDI, SDO, and SCLK) are connected to

compatible. The interface co ntrol

and

Evaluation Board Overview

The board is partitioned into two sections: analog
and digital. The analog section consists of the
CS5529 and a precision voltage reference. The dig­ital section consists of the 80C51 microcontroller,
the hardware test switches, the reset circuitry, and
the RS-232 interface.

The CS5529 is designed to digitize signals while
operating from a 32.768 KHz crystal. As shown in
Figure 1, a signal can be connected to the convert­er’s inputs via J1’s AIN+ and AIN- inputs. Note
that a simple RC network filters the input to reduce
broadband noise.

Figure 2 illustrates the schematic of the digital sec­tion. It contains the microcontroller, a Motorola
MC145407 interface chip, and test swit ches. The
test switches aid in debugging communication
problems between the CDB5529 and the PC. The
microcontroller derives its clock from an 11.0592
MHz crystal. From this, the controller is configured
to communicate via RS-232 at 9600 baud, no pari­ty, 8-bit data, and 1 stop bit.

2 DS246DB1

REF+

AIN+

AIN-

REF-

+5V / 2.5V Analog

-2.5V Analog

J1

JP4

R16

Ω

301

R18

301

R17

301

Ω

Ω

JP3

R15

301

0.1µF

HDR8

C2

4700pF

Ω

4700pF

C16

C1

HDR1

7

HDR2

1, AGND

2, AIN+

1, AIN­2, AGND

1,LT1019

2,REF+
3,REF­4,VA-

VA-

C30

10µF

0.68µF

HDR5

C3

0.68µF

C4

20

19

2

1

3

4

VA+

VA­AIN+

AIN-

REF+

REF-

R21

Ω

10

U4

CS5529

VD+

DGND

CS

SDI

SDO

SCLK

D3
D2

D1

D0

A1
A0

DGND

13

C31

10µF

8

15

14

9

18
17
16

7
6
5

12

CS

CDB5529

HDR3

HDR9

D0D1D2

D3

+5V / 3.3V Digital

To

Figure 2

HDR6

C11

0.1µF

A1

A0

SDI

SDO

SCLK

+5V / 2.5V Analog

VA-

C21

0.1µF

U3

LT1019

2.5V

R22

50

Ω

C15

0.1µF

XOUT

10

Y2
32768Hz

Figure 1. Analog Schematic Section

XIN

11

DS246DB1 3

4 DS246DB1

From

Figure 1

+5V Digital

1N4148

750k

C26

10µF

VCC VDD

3

C2-

1

C2+

MC145407
2

+

R14

Ω

C25

10µF

10k

TXD

RXD

RTS

CTS

DTR

DSR

DCD

J2

RI

9

3

2

7

8

4

6

1

5

17

18

C1-

+

20

C1+

5

6

7

8

9

10

U1

4

C28

10µF

+

CDB5529

+5V Digital

+5V Digital

1

HDR10

Ω
Ω

Y1

+5V Digital

C19

1 2

3 4

5

9

11

13

14

17

R1

Ω

200
R2

Ω

200
R3

Ω

200
R4

Ω

200
R5

Ω

200
R6

Ω

200

R19

Ω

200

R20

Ω

200

6

8

10

12

U5
SN74HC14N

2
3
4
5
6
7
8

18

19

9

TP65

TP64

TP63

TP62

TP61

P1.0
P1.1
P1.2
P1.3
P1.4
P1.5
P1.6
P1.7
P3.5
P3.6

XTAL1

XTAL2

RST

UM1

80C51

VSS

20

CS

SDI

SDO

SCLK

D1
D0

Bypass

Cap

C18

R7
200
R8
200

C23

33pF

C0G

11.0592MHz

C24

33pF

C0G

0.1µF

A1
A0

D2
D3

D4

0.1µF

R9

RESET

Ω

VDD

P0.0

P3.0
P3.1

P3.2
P3.3

P3.4

P2.0

P2.1

P2.2

P2.3

40
39

10
11

12
13
14

5.11k

21

22

23

24

R12

10k

Ω

R13

Ω

JP2

+

R11

5.11k

C7

47µF

Ω

C17

0.1µF

R10

Ω

5.11k

6

5

LED_555_5003

S1

Test Switch 1
Test Switch 2
Test Switch 3

+18

+27

+3

+4

D1

HDR7

From RS-232

To RS-232

RESET

COMM

GAINCAL

OFFSETCAL

Normal

Loopback

C27

10µF

RXD

TP71

TXD

TP721615

+

14

13

12

11

Figure 2. Digital Schematic Section

Register Read Command Byte Write Command Byte

Offset Register 0x90 (H) 0x80 (H)

Gain Register 0x92 (H) 0x82 (H)

Configuration Register 0x94 (H) 0x84 (H)

Conversion Data Register 0x96 (H) ---

Table 1. Microcontroller Command via RS-232

CDB5529

Table 1 lists the RS-232 commands used to com­municate between the PC and the microcontroller.
To develop additional code to communicate to the
evaluation board via RS-232, the following ap­plies: to write to an internal A DC register, choos e
the appropriate write command byte (See Table 1),
and transmit it LSB first. Then, transmit the three
data bytes, lowest order byte (bit s 7-0) first, with
the LSB of each byte transmitted first. These three
data bytes provide the 24-bits of information to be
written to the desired register. To read from an in­ternal register, choose the appropriate read com­mand byte and transmit it LSB first. Then, the

microcontroller automatically acquires the ADC’s
register contents and returns the 24-bits of informa­tion. The returned data is transmitted lowest order
byte first with the LSB of each byte transmitted
first.

The CS5529 A/D converter is designed t o operate
from a single +5V or a dual ±2. 5V analog supply.
Figure 3 illustrates the power supply connections to
the evaluation board. The +2.5/5V Analog supplies
the positive analog section of the evaluation board,

the LT1019 and the ADC. The -2.5V Analog sup­plies the negative. HDR8 (see Figure 1) can be used
to bypass VA- to ground. The +5V Digital supplies
the digital section of the evaluation board. It pow­ers the 80C51, the reset circuitry, and the RS-232
interface circuitry.

Using the Evaluation Board

The CS5529 is a highly integrated ADC. It contains
coarse/fine charge buffers and programmable out­put word rates (OWR). The buffers provide charge
to the modulator reducing the dynamic current de­mand from the signal being digitized and from the
external reference. The ADC’s digital filter allows
the user to select output word rates (OWR’s) from

1.88 Hz up to 101.1 Hz (assum ing a 32.768 kHz
clock). 303 Hz output word rates can be attained
when a 100kHz clock source is used. Since the
CS5529 has such a high degree of integration and
flexibility, the CS5529 data sheet should be read
thoroughly before and consulted during the use of
the CDB5529.

+2.5V / 5V Analog

Z2

P6KE6V8P

Z5

P6KE6V8P

-2.5V Analog

DS246DB1 5

Z3

P6KE6V8P

C6
47µF

+

C5
47µF

+

C20

0.1µF

C14

0.1µF

Figure 3. Power Supplies

R21

Ω

10

AGND

To HDR8

To HDR3

To µC VD+

DGND

C12

0.1µF

C12

0.1µF

C8
47µF

+

C8
47µF

+

+5V / 3.3V A/D Digital

Z4

P6KE6V8P

Z1

P6KE6V8P

+5V Digital

CDB5529

Name Function Description

HDR1 Used to switch AIN+ between J1 input

and AGND.

HDR2 Used to switch AIN- between J1 input

and AGND.

HDR3 Used to switch digital power for the

converter (VD+) from positive analog
supply header (+5V/2.5V Analog) to
the positive digital supply header

(+5V/3.3V Digital).
HDR4 Does not exist.
HDR5 Used to switch VREF+ and VREF-

pins from external J1 connection

header to the on board LT1019 refer-

ence.
HDR6 Used to connect external micro-con-

troller.
HDR7 Used in conjunction with the self test

modes to test the UART communica-

tion between the microcontroller and

the PC.
HDR8 Used to switch the analog compo-

nent’s (LT1019 and converter) nega-

tive potential between the -2.5V

Analog header and AGND.
HDR9 Used in conjunction with HDR3 to

switch the digital ground of the con-

verter (DGND) from the AGND header

to the DGND header.

HDR10 Used to switch the A0 and A1 output

switches of the converter into the

microcontroller. These shunts must be

disconnected when the converter

powered from bipolar supplies.

Software

The evaluation board comes with software and an
RS-232 cable to link the evaluation board to the
PC. The executable software was developed with

TM

Lab Windows/CVI

TM

dows

3.1 or later. After installing the software,

read the readme.txt file for last minute changes in
the software. Additionally, Part II: Software fur­ther details how to install and use the software.

IBM, AT and PS/2 are trademarks of International Busi­ness Machines Corporation.

Windows is a trademark of Microsoft Corporation.
Lab Windows and CVI are trademarks of National

Instruments.
SPI is a trademark of Motorola.
MICROWIRE is a trademark of National Semiconduc-

tor.

and meant to run under Win-

6 DS246DB1