Texas Instruments ADS1254 User manual

 
  
May 2002 Data Acquisition Products
User’s Guide
SLAU083

IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications,
enhancements, improvements, and other changes to its products and services at any time and to discontinue
any product or service without notice. Customers should obtain the latest relevant information before placing
orders and should verify that such information is current and complete. All products are sold subject to TI’s terms
and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI
deems necessary to support this warranty. Except where mandated by government requirements, testing of all
parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for
their products and applications using TI components. To minimize the risks associated with customer products
and applications, customers should provide adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right,
copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process
in which TI products or services are used. Information published by TI regarding third−party products or services
does not constitute a license from TI to use such products or services or a warranty or endorsement thereof.
Use of such information may require a license from a third party under the patents or other intellectual property
of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of information in TI data books or data sheets is permissible only if reproduction is without
alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction
of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for
such altered documentation.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that
product or service voids all express and any implied warranties for the associated TI product or service and
is an unfair and deceptive business practice. TI is not responsible or liable for any such statements.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2002, Texas Instruments Incorporated

EVM IMPORTANT NOTICE
Texas Instruments (TI) provides the enclosed product(s) under the following conditions:
This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION
PURPOSES ONLY and is not considered by TI to be fit for commercial use. As such, the goods being provided
may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective
considerations, including product safety measures typically found in the end product incorporating the goods.
As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic
compatibility and therefore may not meet the technical requirements of the directive.
Should this evaluation kit not meet the specifications indicated in the EVM User’s Guide, the kit may be returned
within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE
WARRANTY MADE BY SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED,
IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY
PARTICULAR PURPOSE.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user
indemnifies TI from all claims arising from the handling or use of the goods. Please be aware that the products
received may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). Due to the open construction
of the product, it is the user’s responsibility to take any and all appropriate precautions with regard to electrostatic
discharge.
EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLE
TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
TI currently deals with a variety of customers for products, and therefore our arrangement with the user is not
exclusive.
TI assumes no liability for applications assistance, customer product design, software performance, or
infringement of patents or services described herein.
Please read the EVM User’s Guide and, specifically, the EVM Warnings and Restrictions notice in the EVM
User’s Guide prior to handling the product. This notice contains important safety information about temperatures
and voltages. For further safety concerns, please contact the TI application engineer.
Persons handling the product must have electronics training and observe good laboratory practice standards.
No license is granted under any patent right or other intellectual property right of TI covering or relating to any
machine, process, or combination in which such TI products or services might be or are used.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2002, Texas Instruments Incorporated

EVM WARNINGS AND RESTRICTIONS
It is important to operate this EVM within the power supply voltage range of 5.5 V to 15 V
(5 V for regulated power inputs) and the analog input range of 0 V to 5 V.
Exceeding the specified supply range may cause unexpected operation and/or irreversible
damage to the EVM. If there are questions concerning the supply range, please contact a TI
field representative prior to connecting the input power.
Applying loads outside of the specified output range may result in unintended operation and/or
possible permanent damage to the EVM. Please consult the EVM User’s Guide prior to
connecting any load to the EVM output. If there is uncertainty as to the load specification,
please contact a TI field representative.
During normal operation, some circuit components may have case temperatures greater than
40°C. The EVM is designed to operate properly with certain components above 40°C as long
as the input and output ranges are maintained. These components include but are not limited
to linear regulators, switching transistors, pass transistors, and current sense resistors. These
types of devices can be identified using the EVM schematic located in the EVM User’s Guide.
When placing measurement probes near these devices during operation, please be aware
that these devices may be very warm to the touch.
Mailing Address:
Texas Instruments
Post Office Box 655303
Dallas, Texas 75265
Copyright 2002, Texas Instruments Incorporated

Information About Cautions and Warnings
iii
Preface
Read This First
About This Manual
This users guide describes the function and operation of the ADS1254EVM
analog-to-digital converter evaluation module. This manual helps you quickly
set up the evaluation module and its accompanying software, so that you can
rapidly test and evaluate the ADS1254. Complete circuit descriptions, as well
as schematic diagrams, PCB layouts, and bill of materials, are also included.
How to Use This Manual
This manual begins with an introductory chapter which describes the EVM and
what it can do. If you are anxious to set things up and start testing, we suggest
you read at least the first two chapters. These two chapters introduce you to
the board and how to set it up to start working with it.
Information About Cautions and Warnings
This book may contain cautions and warnings.
This is an example of a caution statement.
A caution statement describes a situation that could potentially
damage your software or equipment.
This is an example of a warning statement.
A warning statement describes a situation that could potentially
cause harm to you.
The information in a caution or a warning is provided for your protection.
Please read each caution and warning carefully.

Trademarks
iv
Related Documentation From Texas Instruments
Data Sheets Literature Number
ADS1254 SBAS213
MAX3238 SLLS349
MSP430F149 SLAS272
REG1117 SBVS001
REG103 SBVS010O
PA350 SBOS099
SN74LVC1G07 SCES296
SN74LVC1G08 SCES217
SN74LVC1G125 SCES223
FCC Warning
This equipment is intended for use in a laboratory test environment only. It gen-
erates, uses, and can radiate radio frequency energy and has not been tested
for compliance with the limits of computing devices pursuant to subpart J of
part 15 of FCC rules, which are designed to provide reasonable protection
against radio frequency interference. Operation of this equipment in other en-
vironments may cause interference with radio communications, in which case
the user at his own expense will be required to take whatever measures may
be required to correct this interference.
Trademarks
Windows is a trademark of Microsoft Corporation.
If You Need Assistance. . .
If you have questions about this or other Texas Instruments data converter
evaluation modules, feel free to e−mail the data converter application team at
[email protected]. Include the product name in the subject heading.

Contents
v
Contents
1 Introduction 1-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.1 The ADS1254 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 EVM System Overview 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Analog Inputs 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Prototyping Area 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5 Power Requirements 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6 Host Computer Requirements 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Getting Started 2-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.1 Unpacking the EVM 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Default Configuration 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Quick Start 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Operation 3-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1 Jumpers 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.1 JMP1: Reference Source Select 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.2 JMP2, JMP3: Power Source Select 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.3 JMP4: Reference Disconnect 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1.4 JMP5: MCU Disable 3-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Reset Switch 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3 Connectors 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.1 J7: RS-232 Connector 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.2 J6: 3.3-V JTAG Port 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.3 J1, J4, J5, BT1: Power Connectors 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.4 J2: Analog Inputs 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.5 J3: External Reference Input 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.6 J8: External Digital Control 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.7 J9, J10: DSK Motherboard Connectors 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3.8 TP1−6: Test Point 3-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4 Circuit Description 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.1 ADS1254 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.2 Microcontroller 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.3 Clock Generation 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.4 Firmware and Host Communication 3-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4.5 Power Supply 3-11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5 Host PC Software 3-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5.1 Main Window 3-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5.2 Display Modes 3-14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5.3 Setup Dialog 3-15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contents
vi
4 Physical Description 4-1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.1 Board Layouts 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4.2 Schematics 4-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Figures
1−1 ADS1254EVM Block Diagram 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1−2 ADS1254EVM Component Locations 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2−1 Start-Up Display 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−1 Main Window 3-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−2 Setup Dialog 3-16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4−1 Board Layout Top Layer 4-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4−2 Board Layout Bottom Layer 4-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4−3 Schematic (Sheet 1 of 2) 4-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4−4 Schematic (Sheet 2 of 2) 4-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tables
2−1 Factory Jumper Settings 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−1 Jumper/Function Reference 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−2 J7: RS-232 Port Pinout 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−3 J8: 3.3-V JTAG Port 3-5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−4 J1: Unregulated Power Input Connector 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−5 J4: External Digital Power Supply Input Connector 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−6 J5: External Analog Power Supply Input Connector 3-6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−7 BT1: 9-V Battery Connector 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−8 J2: Analog Inputs 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−9 J3: External Reference Input 3-7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−10 J8: 3.3-V JTAG Port 3-8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3−11 TP1−6: Test Points 3-9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

1-1
Introduction
Introduction
This chapter provides an overview of the ADS1254EVM evaluation module
and software.
Topic Page
1.1 The ADS1254 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 EVM System Overview 1-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Analog Inputs 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Prototyping Area 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.5 Power Requirements 1-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6 Host Computer Requirements 1-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 1

The ADS1254
1-2
1.1 The ADS1254
The ADS1254 is a precision 24-bit delta-sigma analog-to-digital converter with
four differential input channels. The delta-sigma architecture employed in the
ADS1254 enables the device to achieve 19 bits of effective resolution (1.8 ppm
RMS noise) at data rates of up to 20 kHz. The part also has a no-missing-codes
characteristic across the full 24 bit range.
The ADS1254 employs an unidirectional two-wire synchronous serial
interface (modified SPI) for communication with the host system. Isolation can
be applied to this interface at minimal cost.
1.2 EVM System Overview
A block diagram of the ADS1254 evaluation module is shown in Figure 1−1.
Figure 1−1.ADS1254EVM Block Diagram
RS-232
Serial Port
MSP430F149
Microcontroller 128 k ×8 SRAM
Clock
Generator
ADS1254
Reference
Buffer
Serial Data
SPI
Inputs
Reference Inputs
System
Clock
During normal operation, data is read from the ADS1254 into the user’s
computer via the ADS1254EVMs RS-232 port. Once read, the data can be
displayed and analyzed in a variety of ways using the supplied ADS1254EVM
software.
The ADS1254 can supply data much faster than it can be transmitted to the
host PC over the RS-232 connection. Because of this, data read from the
ADS1254 is stored in an onboard RAM, where it is kept until retrieved by the
host system. This process is controlled by the user through the ADS1254EVM
software.

Analog Inputs
1-3
Introduction
The ADS1254EVM incorporates a PLL-based clock generator which can
synthesize clocks of nearly arbitrary frequency up to the maximum of 8 MHz.
The PLL exhibits increased jitter, so for certain clock frequencies, a direct
divide-down circuit derived from a crystal oscillator is used instead. The
divide-down is selected automatically.
The ADS1254EVM can be powered using an ac power adapter (not included),
a 9-volt battery, or a user-supplied laboratory power supply.
A photograph of the ADS1254EVM with the locations of major components
highlighted is shown in Figure 1−2.
Figure 1−2.ADS1254EVM Component Locations
CHANNEL INPUTS
EXTERNAL
REFERENCE
INPUT
RS-232 PORT
ANALOG
REGULATED
POWER
DIGITAL
REGULATED
POWER
UNREGULATED
POWER
JTAGADS1254
BATTERY
CONNECTOR
MCU DISABLE VREF DISCONNECT VREF SOURCE SELECT
DIGITAL VDD SOURCE
ANALOG VDD SOURCE
SRAM
MCU
DSK PERIPHERAL CONNECTOR
DSK MEMORY CONNECTOR
EXT DIGITAL
1.3 Analog Inputs
Analog input is supplied through the eight-way screw terminal block, J2. Each
input is connected to the ADS1254 through a 1-kΩresistor. The inputs are not
protected against overvoltage.
1.4 Prototyping Area
A prototyping area is provided on the ADS1254EVM. This may be used to
incorporate additional circuitry, such as special reference or conditioning
circuits, into the system. Certain holes are connected to convenient circuit
points, such as ground, reference, etc.
1.5 Power Requirements
The ADS1254EVM must be supplied with 5.5 V−15 V for proper operation.
Power can be supplied through barrel jack, J1 (tip positive), screw terminal
blocks J4 and J5, or with a 9-volt battery connected to battery snap BT1.

Host Computer Requirements
1-4
1.6 Host Computer Requirements
The ADS1254EVM software is designed to run on a PC running any
Windows platform (Windows 95, 98, NT, 2000, etc.).
Minimum Requirements:
-IBM-compatible 486 PC or higher
-Windows 95/98/2000 or NT4.0
-64 MB RAM minimum
-20 MB available hard disk space
-CD-ROM drive
-Available serial port

2-1
Getting Started
Getting Started
This chapter guides you through unpacking your EVM and setting it up so you
can begin working with it immediately.
Topic Page
2.1 Unpacking the EVM 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.2 Default Configuration 2-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.3 Quick Start 2-3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 2

Unpacking the EVM
2-2
2.1 Unpacking the EVM
After unpacking the ADS1254EVM kit, check to make sure you received all of
the items listed here:
-ADS1254EVM board
-9-pin D-sub male-female serial cable
-Software CD-ROM
If any of these items are missing, contact Texas Instruments to receive
replacements.
2.2 Default Configuration
Although much of the ADS1254EVMs operation is controlled by the host PC,
some configuration must be done directly on the board, using five jumpers
(shorting blocks). The ADS1254EVM is configured as follows at the factory:
Table 2−1.Factory Jumper Settings
Jumper Identifier Description Default Setting
JMP1 External reference select 2−3
JMP2 Digital power supply source 1−2
JMP3 Analog power supply source 1−2
JMP4 Reference disconnect 1−2
JMP5 MCU disable Disconnected
For more information about the jumpers, see Section 3.1.

Quick Start
2-3
Getting Started
2.3 Quick Start
Once the ADS1254EVM has been unpacked from its shipping container, and
you have verified that the board is configured as shown in Table 2−1, it can be
powered on and tested.
First, connect the board to the host PC using the supplied 9-pin serial cable.
Then power the board on by plugging a wall power adapter into a suitable ac
power source and plugging the barrel plug into the barrel jack on the
ADS1254EVM, or by connecting your laboratory power supply to the external
power inputs and setting JMP2 and JMP3 to the 2−3 position. (You do not have
to connect the serial cable first; it is also acceptable to apply power to the board
first.) When the board is properly powered on, the two power good indicator
lamps near the power connectors glow brightly. (The 5-V LED may glow
brighter than the 3.3-V LED; this is normal.)
Place the CD-ROM into your PCs CD-ROM drive. Locate the setup program
on the disk, and run it. The setup program installs the ADS1254EVM software
on your PC. If you are running a Windows platform that is NT-based, such as
Windows NT or Windows 2000, you need administrator privileges to install the
software. Follow the instructions that the installer gives you.
Once the program has been successfully installed, it can be executed. When
the program is run, it displays a title screen, and then you see something like
the display in Figure 2−1.
Figure 2−1.Start-Up Display

Quick Start
2-4
The setup window appears first, allowing you to make adjustments to the
programs configuration. For the test run, you should select the serial port to
which the ADS1254EVM is connected, using the serial port menu.
If no serial ports are available, a message box appears informing you that the
program cannot run. This is usually because other programs are using all of
the available serial ports. If this is the case, closing these programs and
rerunning the program should fix the problem.
Once the correct serial port has been selected, click OK. The setup dialog
disappears and you see the main window. Click the acquire button. After a
period of activity, you see data displayed in the data display window.

3-1
Operation
−
Operation
This chapter describes each function of the ADS1254EVM, and how to use the
accompanying software to control the ADS1254.
Topic Page
3.1 Jumpers 3-2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Reset Switch 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.3 Connectors 3-4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.4 Circuit Description 3-10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.5 Host PC Software 3-12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Chapter 3

Jumpers
3-2
3.1 Jumpers
Table 3−1 shows the function of each jumper on the EVM:
Table 3−1.Jumper/Function Reference
Reference
Designator Setting Function Default Section
JMP1 1 to 2 External reference 2−3 Section 3.1.1
2 to 3 Onboard reference
JMP2 1 to 2 Digital power supplied from barrel
jack, battery, or DSK 1−2 Section 3.1.2
2 to 3 Digital power supplied from screw
terminal block J4
JMP3 1 to 2 Analog power supplied from barrel
jack, battery, or DSK 1−2 Section 3.1.2
2 to 3 Analog power supplied from screw
terminal block J4
JMP4 Connected Reference pin is connected Connected Section 3.1.3
Disconnected Reference pin is not connected
JMP5 Connected MCU controls ADS1254 Disconnected Section 3.1.4
Disconnected MCU does not control ADS1254
3.1.1 JMP1: Reference Source Select
The ADS1254EVM can use an externally supplied reference or an onboard
4.096-V zener reference (D1 and R1); use JMP1 to connect the desired
reference source. Shorting pins 1 and 2 connects the external reference;
shorting pins 2−3 connects the onboard reference.
3.1.2 JMP2, JMP3: Power Source Select
The ADS1254 has separate analog and digital power supplies. JMP2 is used
to select the source for the digital power supply, and JMP3 is used to select
the source for the analog supply. To use the barrel jack or battery (onboard
regulator), short pins 1−2; if you wish to use an external power supply, short
pins 2−3.
3.1.3 JMP4: Reference Disconnect
JMP4 is used to connect an external reference directly to the ADS1254, with-
out using the onboard filtering. Removing this jumper disconnects the
ADS1254 reference pin. External reference voltage must be applied to pin 2.

Jumpers
3-3
Operation
3.1.4 JMP5: MCU Disable
Shorting the pins of this jumper has the same effect as plugging the
ADS1254EVM into a DSP DSK: the onboard regulators are shut down, and if
power is still available, the MCU is disabled. Power may still be supplied
through the external power connectors J4 and J5, or through the DSK;
however, power cannot be supplied to the onboard clock generator from the
DSK, since the clock generator is only supplied from the onboard regulators.
If you want to use an external system to control the ADS1254, instead of the
onboard MCU, you must connect this jumper to prevent conflicts with the MCU.
Since this jumper disables the onboard power supply, you must also power the
board externally.
If JMP5 is shorted, and power is available to the MCU, it is active, but it
effectively disconnects itself from the ADS1254 by 3-stating any pins leading
to the 1254. This prevents conflicts with the DSK. The MCU can still
communicate with the host PC in this mode.

Reset Switch
3-4
3.2 Reset Switch
Switch SW1 is a miniature pushbutton which, when pressed, forces the MCUs
RESET line low. When released, the MCU enters a reset cycle. If
communication becomes disrupted between the host and the board, or the
board is unresponsive, pressing RESET returns the system to normal
operation.
3.3 Connectors
The various connectors on the ADS1254EVM are described in this section.
3.3.1 J7: RS-232 Connector
The host PC controls the board through this connector, which is a 9-pin female
D-shell type, pinned out in the usual manner. Certain of the flow control lines
are used for special purposes by the ADS1254EVM board; these are
described in the table.
In the RS-232 electrical specification, −5 V to –15 V on a line indicates a logic
high (mark), and 5 V to 15 V indicates logic low (space). Line states are
described here according to their logical states.
If a non-handshaking RS-232 cable is used, that is, one which connects only
RD, TD, and signal ground. The board can still operate normally, but it cannot
be reset by the host PC, and bootstrap firmware upgrading cannot be
performed through the serial port (it can still be done through the JTAG port
J6, but this requires a special programming adapter and software).
Table 3−2.J7: RS-232 Port Pinout
Pin
Number Signal Name RS-232 Name Direction (at board) Function
1 DCD Data carrier detect Output None
2 RD Receive data Output Serial data output to host PC
3 TD Transmit data Input Serial data input from host PC
4 DTR Data terminal ready Input Connected to the MCUs reset circuit. A low
on this line resets the MCU. Must be held
high for normal operation
5 SG Signal ground Power Ground reference
6 DSR Data set ready Output None
7RTS Request to send Input Connected to TCK on MCU. Used for boot-
strap firmware loading. Must be held high
for normal operation
8 CTS Clear to send Output None
9 RI Ring indicator Output None